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458
FOUNDATIONS: A GENERAL APPROACH TO HAND 
INJURIES
Complaints regarding the hand present frequently to the emer-
gency department with evaluation and management challenges due 
to the complex anatomy and function of the hand. Careful review of 
hand injuries is needed to identify simple wounds, injuries that can 
be initially managed but need further treatment, or time- sensitive 
emergencies. The disposition of the patient may involve simple fol-
low- up or consideration for the need for specialized consultants.
The initial evaluation of a patient presenting with a hand injury 
should include a focused, but thorough, history and physical exam. 
The patient’s age, mechanism of injury, time of injury, other acute or 
distracting injuries, hand dominance, occupation, and any prior hand 
injuries or impairments should be queried. For penetrating injuries, 
tetanus immunization status should be assessed, and for patients who 
may require surgical management, the timing of the last solid or liquid 
ingestion or nil per os (NPO) status should be assessed. For nontrau-
matic hand complaints, the presence of contracture, timing of symp-
toms, pain, aggravating or alleviating factors, presence of symptoms in 
other extremities, as well as functional impairment are additional key 
components of the history.
The hand should be completely exposed and examined, including 
all components as listed in Box 42.1. Inspection to identify deformity, 
discoloration, swelling, ecchymoses, laceration, or signs of open frac-
ture should occur. Angular deformities are best evaluated with the fin-
gers in full extension. Rotational deformities are best evaluated with 
the fingers in flexion. Severe hand injuries create the appearance of 
significant tissue loss or destruction which should not distract the pro-
vider from providing basic or advanced trauma care.
A neurovascular assessment should be performed and documented 
using the Allen test, capillary refill, and two- point discrimination. The 
point of maximal tenderness should be noted. Tendon, ligament, and 
joint capsule integrity should be examined with special testing per-
formed where it is relevant to the patient’s injury or complaint. Wound 
exploration may be necessary to assess for foreign bodies, gross con-
tamination, or structural injury. Proper analgesia and regional blocks 
should be considered prior to wound exploration, which should be 
performed with sterile technique.
Radiographic imaging is the most widely available and used imag-
ing modality for the hand. It is essential to obtain sufficient views to 
adequately assess the areas of injury. A standard x- ray series of the 
hand should include a posterior- anterior (PA), lateral (90 degrees to 
the PA), and generally, at least one oblique film. The ideal x- ray film 
should have no overlapping of bones, allowing for proper evaluation 
of each joint space, radiopaque foreign bodies, dislocations, and frac-
tures. If possible, all rings, jewelry, and watches should be removed 
before imaging. Comparison of films performed on the uninjured side 
may assist in pediatric patients with developing growth plates.
Ultrasound imaging has also been shown to be a useful, though 
inferior, bedside modality for detecting fractures of the hand. A recent 
meta- analysis of 8 randomized control trials (RCTs) and prospective 
studies found a pooled sensitivity and specificity of 91% and 96% 
respectively in identifying fractures of the phalanx and metacarpals 
using x- ray as the gold standard.1 Another blinded study looking at 
point- of- care ultrasound (POCUS) performed by emergency medicine 
Hand Injuries
Benjamin Schoener and Mary Jo Wagner
42
KEY CONCEPTS
 • For general testing of the motor nerve function of the hand, have the patient 
make an “OK” sign with their thumb and index finger (testing the median 
nerve), while spreading/abducting the third, fourth, and fifth fingers (ulnar 
nerve) and dorsiflexing the wrist (radial nerve).
 • For general sensory exam, test two- point discrimination on the finger tufts 
of the index finger (median nerve), the little finger (ulnar nerve), and the 
dorsum of the first webspace (radial nerve).
 • The most important treatment for the majority of hand injuries is applying 
an appropriate splint. The neutral position for general fractures of the hand 
or fingers is achieved by placing a volar splint ideally with the wrist at 20 to 
30 degrees extension, MCP at 70 to 90 degrees flexion, and the PIP and DIP 
kept in extension. This is also known as intrinsic plus position.
 • The most common extensor tendon injury is a terminal tendon disruption 
from sudden flexion of the extended DIP joint resulting in a mallet injury.
 • A flexor tendon injury should be considered when an injured finger does not 
assume its naturally flexed position on cascade sign testing.
 • Traditionally, patients with acute open wounds on the hand have been 
treated prophylactically with antibiotics, but there is little scientific data 
supporting the clinical efficacy of this practice.
 • For a stable finger tuft with a subungual hematoma without external disrup-
tion of the nail plate, trephination without antibiotics is the only treatment 
needed.
 • Small tuft avulsions defined as less than 1 cm3 can be treated conserva-
tively, while larger amputations should have emergent consultation with 
a hand surgeon for consideration for flap coverage or reimplantation. The 
presence of exposed bone or tendon indicates the need for surgical inter-
vention.
 • Most hand infections are based on skin flora; treatment for outpatient 
injuries are oral first- generation cephalosporins. With the growing emer-
gence of community- acquired MRSA, antibiotics such as doxycycline, 
TMP- SMX, or clindamycin should be considered. For inpatient injuries, IV 
first- generation cephalosporins or vancomycin is recommended.
 • The four classic Kanavel findings for infectious flexor tenosynovitis are fusi-
form swelling of the digit, tenderness along the tendon sheath, digit held in 
flexion at rest, and pain with passive extension of the digit.
459CHAPTER 42 Hand Injuries
(EM) physicians, found a lower sensitivity of 79% and specificity of 
90% for phalanx fractures.2 Ultrasound is also helpful in evaluation of 
the soft tissue and for detection of foreign bodies.
CT and MRI are rarely used for evaluation in the acute setting, 
although they are occasionally used for evaluation of complex fractures 
or if there is a high clinical suspicion of fracture with negative x- ray 
imaging. MRI has the added ability to visualize the ligaments, tendons, 
and soft tissues. It is an effective imaging modality for investigating 
suspected osteomyelitis, avascular necrosis, and bone tumors.
Anatomy
Surface Anatomy and Skin
To understand the surface anatomy of the hand, it is important to 
be familiar with certain landmarks and associated terminology. The 
posterior surface of the hand is referred to as the dorsal surface, and 
the palmar surface of the hand is referred to as the volar surface. 
The radial border of the hand is that which borders the thumb, and 
the ulnar border of the hand is that which borders the little finger 
(Fig. 42.1).
The skin on the dorsal surface of the hand is generally thin and 
mobile compared to the volar surface. Unlike the volar surface, the dor-
sal surface is more prone to swelling. Also unique to the dorsal surface 
is the presence of hair follicles and the presence of the nail bed at the 
distal phalanges.
The volar surface of the hand is thick and stable. It is layered with 
subcutaneous fat and a thick dermis designed in a series of transverse 
folds or creases. This allows for sufficient padding and firmness with 
gripping. The folds are anchored directly to fascia in areas without 
underlying fatty tissue. This allows for easier flexion and limits the 
development of inflammation and edema. A collection of underlying 
muscles that respectively form the thenareminence and the hypothe-
nar eminence at the radial border and the ulnar border are also identi-
fiable on the volar surface of the hand.
Fingertip and Nail. The fingertip is the area distal to the DIP and 
insertion of the flexor digitorum profundus (FDP) and extensor 
tendons. The volar surface is well- innervated, vascularized, and padded 
with adipose tissue. This area, which is anchored to the distal phalanx, 
is also known as the pulp.
The fingernails are specialized structures of keratinized epithelium 
that protect the distal phalanges. Underneath the nail, also known as 
the nail plate, is the nail bed which is comprised of skin (Fig. 42.2). 
BOX 42.1 General Hand Exam
 I. Inspection
 A. Skin
 • Wounds
 • Erythema
 • Pallor (arterial compromise)
 • Cyanosis
 B. Edema
 C. Deformity
 • Rotation
 • Angulation
 • Cascade sign
 II. Range of Motion
 A. Active
 B. Passive
 III. Palpation
 A. Warmth
 B. Joint effusion
 C. Tenderness
 D. Masses (i.e., nodules, ganglions)
 IV. Neurovascular Exam
 A. Motor
 • Median N.—Flexion of thumb and index finger (“OK sign”)
 • Radial N.—Extension of thumb against resistance
 • Ulnar N.—Abduct fingers against resistance
 B. Sensation
 • Two- point discrimination
 C. Vascular
 • Allen test
 • Capillary refill at nail beds
Distal
Phalanx
Distal
Palmar Thenar
DIP
PIP
Palmar
Digital
Proximal
Palmar
Thenar
Eminence
Hypothenar
Eminence
Wrist
Middle
Phalanx
Proximal
Phalanx
Radial Ulnar
I
III
II
IV
V
A B
Creases
Fig. 42.1 (A) Dorsal and (B) volar views of the hand with digits I–V, palmar creases, and surface anatomy 
labeled (Courtesy of Benjamin Schoener, MD and Harrison Zeitler, MD; Central Michigan University COM)
460 PART II Trauma
The distal part of the nail is known as the nail body and the proxi-
mal portion of the nail is the nail root. The point of division is at the 
distal lunula, visible on exam as the white crescent- shaped area of the 
nail bed. The lunula represents the distal end of the germinal matrix, 
which is responsible for generation of the nail plate, which grows dis-
tally along the nail bed. Damage to the germinal matrix may lead to 
permanent damage of the nail plate. The insertion of the extensor ten-
dons is found as distal as the lunula with a similar location for insertion 
of the flexor digitorum profundus (FDP), so damage to this area can 
result in tendon dysfunction. The small area of skin covering the prox-
imal nail is known as the eponychium or cuticle. The hyponychium is 
skin underlying the distal nail plate. The paronychium refers to the skin 
overlying the lateral portions of the nail plate.
Examination of the nail bed by checking for capillary refill is 
important when assessing a patient’s perfusion status. Additionally, the 
nail itself should be assessed for clubbing, spooning, splinter hemor-
rhages, discoloration, and thickness.
Skeletal Anatomy and Ligaments
The hand is comprised of five digits: four fingers and one thumb. Each 
digit is numbered from I to V with digit I being the thumb and digit 
V being the little finger. The fingers contain a distal, middle, and prox-
imal phalanx, while the thumb only has a proximal phalanx and a 
distal phalanx. The joints of the hand from proximal to distal include 
the carpometacarpal (CMC), metacarpophalangeal (MCP), proximal 
interphalangeal (PIP), and the distal interphalangeal joints (DIP) (Fig. 
42.3). Proximal to the metacarpals are the 8 carpal bones which are 
tightly bound by ligaments which creates a concave formation on the 
volar surface. This is held together by the flexor retinaculum, a strong 
fibrous band, which forms the carpal tunnel, containing the median 
nerve and flexor tendons passing from the forearm. The boundaries of 
the carpal tunnel include the flexor retinaculum volarly and the carpal 
bones medially and laterally.
Bone development in the hand differs from other long bones. The 
thumb metacarpal epiphysis and phalangeal epiphyses are located at 
the proximal end. The finger metacarpal epiphyses are located at the 
distal end. The ossification centers of the phalanges and metacarpals 
appear at 10 to 36 months of age and usually fuse by age 14 to 16 years, 
with females having ossification earlier than males in general. The 
Hyponychium
Sterile
matrix
Sterile matrix
Lunula
Lunula
Eponychium
Eponychium
Nail fold
Nail fold
Nail wall
Nail root
Nail bed
Germinal matrix
Germinal matrix
Body
of
nail
Root
Fingernail
Fig. 42.2 Fingernail with labeled anatomy. (From: Buttaravoli P, Leffler, 
Stephen M. Minor Emergencies, ed 3. Philadelphia: Elsevier Saunders; 
2012:535-538.)
Joints Bones
Distal phalanges
Distal
interphalangeal
(DIP)
Proximal
interphalangeal
(PIP)
Metacarpo-
phalangeal
(MCP)
Interphalangeal
Metacarpo-
phalangeal
Carpometacarpal
(“saddle joint”)
Trapezoid
Trapezium
Scaphoid
Middle phalanges
Proximal phalanges
Metacarpals
Hamate
Pisiform
Triquetrum
Lunate
Capitate
Fig. 42.3 Anatomy of the bones and joints of the hand. (Trott AT. Wounds and Lacerations: Emergency Care 
and Closure. Philadelphia: Elsevier Saunders; 2012:161-191.)
461CHAPTER 42 Hand Injuries
ossification center of the middle finger generally develops first and the 
fifth generally develops last.
The DIP and PIP joints of the fingers are uniaxial hinge joints that 
move along a sagittal plane. The DIP joint can flex to a maximum of 
90 degrees whereas the PIP joint can flex up to 105 degrees from full 
extension. The DIP and PIP joints are structurally identical in that 
they both have a bicondylar configuration with a tongue- in- groove 
insertion of the distal phalanx. This configuration on both sides of the 
joint, in addition to collateral ligaments (also known as retinacular 
ligaments), is responsible for lateral stability and resisting of lateral, 
oblique, and rotatory forces. To provide additional stability, a fibrocar-
tilaginous volar plate forms the anterior surface of the IP joint. The 
volar plate, along with a pair of check ligaments, serves to reinforce the 
joint capsule and limit hyperextension.
To evaluate any rotational deformities of the fingers in flexion, the 
cascade sign test may be used (Fig. 42.4). With the patient’s elbow 
flexed to 90 degrees and the forearm supinated, the patient closes his 
or her hand with the thumb remaining open. Normally, the fingers 
should come together over the thenar and hypothenar eminences and 
point toward the scaphoid region. However, if there is overlap of the 
fingers or they are askew, this is a positive cascade sign, indicating 
rotational deformity often associated with metacarpal or phalangeal 
fractures.
In contrast to the IP joints, the MCP joints are less stable. They are 
formed by a rounded head of the metacarpal bone inserting into the 
concave surface of the proximal phalanx. This facilitates an efficient 
grasp by allowing for some rotational movement and side- to- side 
mobility. The MCP joints also contain a volar plate and collateral liga-
ments, though the volar plates of the MCP joints, unlike the IP joints, 
are interconnected by a deep transverse ligament. Additionally, the arc 
of rotation of the MCP joint depends on the degree of flexion of the 
proximal phalanx. As the MCP joint is flexed from 0 to 90 degrees, 
the collateral ligaments transition from a relaxed to a tight functional 
state. The integrity of the collateral ligaments should be tested when 
the MCP joint is fully flexed, where there should be no ability to abduct 
or adduct the phalanx. This is in contrast to the extended state, where 
limited side- to- side mobility is possible.
The functional anatomy of the MCP joint also illustrates the impor-
tance of splinting the joint in flexion to avoid shortening and subse-
quent stiffening of the collateral ligaments. Functional positioning is 
essential for proper splinting of the hand (Fig. 42.5).
The arrangement of the metacarpals creates three arches: the prox-
imal (carpal) anddistal (metacarpal) transverse arches and the lon-
gitudinal arch (Fig. 42.6). The articulations between the carpal and 
metacarpals for the second and third digits are essentially fixed, mak-
ing them relatively immobile in comparison to the articulations of the 
fourth and fifth digits, which have 15 and 25 degrees of movement, 
respectively. This variability creates a transverse and longitudinal con-
cavity when the thumb is adducted against the index finger.
The joints of the hand should be properly examined for erythema, 
pallor, and swelling. They should also be examined for excessive 
warmth to assess for inflammatory arthritis. Cool or discolored digits 
may indicate vascular pathology or Raynaud phenomenon. Both pas-
sive and active range of motion of the joints should be assessed (Box 
42.2). Crepitus may be present with a joint effusion or inflammatory 
arthritis. Clicking or snapping may indicate that tendonitis is present.
Musculature and Tendons
The muscles of the hand are divided into two groups: intrinsic and 
extrinsic. The intrinsic hand muscles contain origins and insertions 
within the hand itself, whereas the extrinsic hand muscles include ori-
gins proximal to the hand with tendon insertions within the hand.
Intrinsic Musculature. The intrinsic hand muscles include the 
muscles of the thenar and hypothenar eminences as well as the adductor 
A B
Fig. 42.4 Cascade of the hand. (A) Demonstration of cascade testing where the hand is positioned with the 
palm upward. Notice the gradual increase in flexion from radial to volar for joints of the hand. (B) Abnormal 
cascade in a patient following a crush injury. There is overlap of digits with a rotational deformity. (From: [A] 
Odak S, Bhalaik V. Assessment of the acutely injured hand. Orthop Trauma. 2014;28(4):199-204; [B] Courtesy 
of Tiffany Weiss- Feldkamp, DO and David Kramp, MD; Central Michigan University COM)
30°
70-90°
0°
Fig. 42.5 Functional position of the hand with the wrist at 30 degrees 
extension, the MCP joint at 70-90 degrees flexion, and the PIP and 
DIP joints fully extended. (From: Yang G, McGlinn EP, Chung KC. Man-
agement of the stiff finger: evidence and outcomes. Clin Plast Surg. 
2014;41(3):501-512.)
462 PART II Trauma
pollicis, lumbricals, and interossei. These muscles are innervated by the 
median and ulnar nerves.
The muscles of the thenar eminence cover the metacarpal of the 
thumb and include the abductor pollicis brevis, flexor pollicis brevis, 
and the opponens pollicis. The names of these muscles describe their 
function and they are controlled by the recurrent branch of the median 
nerve. The muscles are easily palpable over the volar surface of the 
hand proximal to the MCP joint of the thumb.
Another muscle in this location, the adductor pollicis, arises from 
the capitate and bases of the second and third metacarpals. Unlike 
other muscles in this location, it is innervated by the ulnar nerve and 
functions to adduct the thumb and rotate it medially. The adductor 
pollicis, as well as ulnar nerve function, can be tested by asking the 
patient to hold a piece of paper between the thumb and index finger. If 
when the examiner attempts to pull the paper out of the patient’s hand, 
the patient is unable to hold on, or there is flexion of the thumb at the 
IP joint, this indicates weakness of the adductor pollicis muscle. This 
is also known as the Froment paper sign (Fig. 42.7). The patient flexes 
his or her thumb because the median nerve–innervated flexor pollicis 
longus tendon takes over to allow the thumb to grasp the paper when 
the adductor pollicis is weak.
The muscles of the hypothenar eminence include the opponens dig-
iti minimi, flexor digiti minimi, and abductor digiti minimi. All three 
muscles aid in movement of the little finger and are innervated by the 
ulnar nerve. Strength of these muscles may be evaluated by having the 
patient hold a piece of paper between the thumb and little finger or by 
having the patient attempt to abduct the little finger against resistance.
Distal
transverse arch
A
C
ED
B
Distal
transverse
arch
Proximal
transverse
arch
Capitate
Longitudinal
arch
Fig. 42.6 (A) The longitudinal and transverse arches of the hand and their relationship to the metacarpals. (C) 
Proximal transverse arch. (D & E) Articulations of the thumb are unique and contribute to the intrinsic arches 
to create an array of grasp positions. (A from Erickson M, et al. Anatomy and kinesiology of the hand. In: 
Rehabilitation of the Hand and Upper Extremity. Jan 1, 2021. (c) 2021. Fig. 1.3; B–E courtesy Dr. D.A. Stearns, 
Department of Emergency Medicine, Massachusetts General Hospital, Harvard Medical School, Boston.)
BOX 42.2 Maximum Joint Range of Motion
 I. Fingers
 • MCP: 0 to 90 degrees flexion
 • PIP: 0 to 110 degrees flexion
 • DIP: 0 to 85 degrees flexion
 II. Thumb
 • MCP: 10 degrees hyperextension to 70 degrees flexion
 • IP: 15 degrees hyperextension to 90 degrees flexion
463CHAPTER 42 Hand Injuries
The lumbricals originate from tendons of the flexor digitorum pro-
fundus (FDP) and insert at the extensor hood and the base of the prox-
imal phalanx. They function to flex the MCP joints and extend the IP 
joints. The ulnar two lumbricals are innervated by the ulnar nerve and 
the radial two lumbricals are innervated by the median nerve.
The interossei muscles are divided into dorsal and palmar interos-
sei. The four dorsal interossei are located in the intermetacarpal spaces 
and function to abduct the fingers. The three palmar interossei are also 
located in the intermetacarpal spaces and insert at the base of the second, 
fourth, and fifth proximal phalanx. They function to adduct the fingers. 
All interossei are innervated by the deep branch of the ulnar nerve.
Extrinsic Musculature. The extrinsic hand muscles are those that 
originate proximal to the wrist and insert within the hand. Most 
extrinsic hand muscles originate in the forearm. The dorsal forearm 
contains extensor muscles of the wrist and fingers as well as abductors 
of the thumb. The volar forearm contains flexor muscles of the wrist, 
thumb, and other fingers.
Extensor Muscles and Tendons. The extensors tendons pass through 
the dorsum of the wrist at 6 different compartments and are innervated 
by the radial nerve (Fig. 42.8). Compartment 1 is located most radial 
and contains the abductor pollicis longus and extensor pollicis brevis 
tendons which form the lateral border of the anatomical snuffbox. Both 
muscles are innervated by the posterior interosseus nerve, a branch of 
the radial nerve. Compartment 3 contains the extensor pollicis longus 
tendon, which forms the medial border of the anatomical snuffbox. 
The tendons forming the borders of the anatomical snuffbox are easily 
palpable and often visible when the thumb is held in abduction and 
extension. Compartment 2 contains the extensor carpi radialis longus 
and extensor carpi radialis brevis tendons, which insert at the base of 
the second and third metacarpals, respectively. Both muscles act to 
extend and abduct the hand at the wrist.
Compartment 4 contains the extensor indicis and extensor digito-
rum communis (EDC) tendons. The extensor indicis proprius (EIP) 
inserts into the extensor hood, which is a dorsal aponeurosis of the 
index finger. The EDC tendons similarly insert into the extensor hood 
of the middle and distal phalanges of the second, third, fourth, and fifth 
fingers. The muscles of compartment 4 function to extend the 4 digits 
and the hand, though primarily at the MCP joint. Extensions of ten-
dons from the extrinsic and intrinsic muscles form an extensor com-
plex on the dorsum of the fingers. Extensions from the lumbrical and 
interosseus muscles connect with extensions of the extensor digitorum 
tendons to form the extensor hood (expansion). The expansion divides 
into three bands—two lateral bands and a central tendon (central slip). 
The three bands are held together by the transverse retinacularliga-
ment preventing volar displacement of the lateral bands which would 
result in PIP flexion as seen in the boutonnière deformity (Fig. 42.9).
Compartment 5 contains the extensor digiti minimi (EDM) tendon 
which inserts at the extensor expansion at the base of the fifth digit 
and extends it at all joints. Compartment 6 contains the extensor carpi 
ulnaris (ECU) tendon which inserts at the fifth metacarpal and func-
tions to extend and adduct the wrist.
Of relevance to identifying and diagnosing an extensor tendon 
injury are the zones of the extensor tendons. This will be discussed in 
depth under extensor tendon injuries.
Flexor Muscles and Tendons. The anterior forearm contains 
muscles responsible for flexion of the wrist, hand, and digits and can 
be divided into an anterior compartment and posterior compartment.
The flexor carpi radialis (FCR), flexor carpi ulnaris (FCU), and pal-
maris longus (PL) tendons are responsible for flexion of the hand at the 
wrist. The flexor carpi radialis (FCR) inserts at the base of the second 
and third metacarpals and is controlled by the median nerve. In addi-
tion to flexion of the wrist, it is responsible for abduction of the hand 
at the wrist. The flexor carpi ulnaris (FCU) inserts at the hook of the 
hamate and base of the fifth metacarpal. It is controlled by branches 
of the ulnar nerve and is responsible for flexion and adduction of the 
hand at the wrist. The palmaris longus muscle inserts at the palmar 
aponeurosis and flexor retinaculum. It is controlled by the median 
nerve and is responsible for wrist flexion. It can be visible and palpable 
when one flexes the wrist and touches the pads of the fourth finger and 
thumb together. Of note, it is innately absent in approximately 25% 
of patients.3 Both the palmaris longus and flexor carpi ulnaris (FCU) 
partially insert at the flexor retinaculum, a fibrous band covering the 
carpal bones and forming the roof of the carpal tunnel.
The flexor digitorum profundus (FDP), flexor digitorum superficia-
lis (FDS), and flexor pollicis longus (FPL) are responsible for flexion of 
the digits and enter the hand via the carpal tunnel. All three muscles 
are innervated by the median nerve or one of its branches with the 
exception that movement of the fourth and fifth digits via the FDP is 
controlled by the ulnar nerve. The FDP originates over the proximal 
body of the ulna and fans out into 4 tendons which insert at the base 
of the distal phalanges. The FDP primarily functions to flex the fingers 
at both interphalangeal joints. The flexor digitorum superficialis (FDS) 
lies superficial to the FDP in the forearm and similarly fans into 4 ten-
dons, though these insert at the base of the intermediate phalanges of 
digits 2 through 5. The FDS primarily functions to flex the PIP joints. 
Fig. 42.7 Froment sign demonstrated in a patient with left ulnar nerve 
weakness. The patient attempts to hold onto the paper with the thumb 
IP joint in flexion and the MCP joint in hyperextension. (Kakinoki R. 
Examination of the upper extremity. In: Plastic Surgery: Vol 6: Hand and 
Upper Extremity, ed 4. London: Elsevier; 2017:49-70.)
Thenar muscles
Adductor pollicis
Hypothenar 
muscles
Dorsal 
interossei 
fascia
Dorsal 
interossei 
Palmar interossei 
First dorsal
interosseous
Fig. 42.8 Cross- sectional view of the compartments of the hand. (Lin 
PY, Sebastin SJ, Chung KC. Fasciotomy of the upper limb. In: Chung KC, 
ed. Operative Techniques: Hand and Wrist Surgery, ed 2. Philadelphia: 
Elsevier Saunders; 2012.)
464 PART II Trauma
To test for FDS integrity, the examiner should flex the associated finger 
against resistance at the PIP while holding the other fingers in exten-
sion to control for FDP action (Fig. 42.10). The flexor pollicis longus 
functions to flex the thumb and inserts at the base of its distal phalanx 
(Table 42.1).
Digital Flexor Sheath. The digital flexor sheath of the hand 
is a closed system of synovial membranes that is divided into 
membranous and retinacular components. The membranous portion 
contains interdigitations between the retinacular tissue and tendons. 
Of note, the synovial sheaths of the flexor tendons are avascular 
systems and thus are more prone to infection. Extensor tendons, 
which do not have similar sheaths, are less likely to develop infectious 
tenosynovitis (Fig. 42.11).
The retinacular component is also described as the “pulley system” 
that overlies the synovial sheath which consists of the palmar aponeu-
rosis (PA) pulley, 3 cruciform pulleys, and 5 annular pulleys. Of note, 
the thumb flexor tendon sheath has its own pulley system (Fig. 42.12). 
The overall function of the pulley system is to maintain tendons in axis 
with flexion of the MCP and ICPs, thereby preventing “bowstringing.” 
The A2 and A4 pulleys are the most essential to preserve.
Blood Supply
Arterial Supply. The radial and ulnar arteries are primarily 
responsible for blood supply to the hand. The radial artery courses 
through the anatomical snuffbox where it branches into the deep 
palmar arch and the superficial palmar arch. The princeps pollicis 
A
B
MP
MP
Sagittal
band
Sagittal
band
Dorsal, volar
interosseous
Trans ret. lig.
Triangular lig.
Obl. ret. lig.
Obl. ret. lig.
(Landsmeer)
Lumbrical
Lat. band
Central slip
extension
PIP
PIP
DIP
DIP
C
E F D
ET
LB
LB
LB
LB
CS
MCP
MCP
I L
PIP
DIP
DIP
Fig. 42.9 Finger extensor complex. (A and B) The extensor hood is formed by a sagittal band originating from 
metacarpal ligaments and volar plate. The intrinsic tendons lumbrical (L) and interosseous (I) muscles insert 
into the extensor mechanism along the proximal dorsal phalanx. (C and D) The extension complex at the PIP 
joint contains a central slip (CS), which inserts on the dorsal base of the middle phalanx and two lateral bands 
(LB). The lateral bands insert at the dorsal base of the distal phalanx, extending beyond the distal interphalan-
geal (DIP) joint. (E and F) The PIP extension mechanism over the PIP joint is maintained by the transverse and 
triangular ligaments, preventing the lateral bands from migrating anteriorly, which would result in paradoxical 
PIP joint flexion. (F) Demonstration of boutonnière deformity where the PIP joint of the index finger is para-
doxically flexed with DIP extension. (A, D–F: Courtesy Dr. D.A. Stearns, Department of Emergency Medicine, 
Massachusetts General Hospital, Harvard Medical School, Boston; B, C: from: Doyle JR. Extensor tendons—
acute injuries. In Green DP, ed. Operative Hand Surgery. New York: Churchill Livingstone; 1998:1928.)
465CHAPTER 42 Hand Injuries
Fig. 42.10 Demonstration of individual testing of flexor digitorum superficialis (FDS) and flexor digitorum 
profundus (FDP) tendon integrity (A) The index finger FDS tendon is examined by asking the patient to flex 
the corresponding proximal interphalangeal (PIP) joint while the adjacent digits are held in extension by the 
examiner. (B) FDP integrity is assessed by asking the patient to flex the distal interphalangeal (DIP) joints of 
each digit individually while the corresponding PIP joints are stabilized in extension by the examiner. (C–E) The 
ring finger’s flexor digitorum profundus (FDP), FDS, and lumbrical functions are tested individually. (Courtesy 
Dr. D.A. Stearns, Department of Emergency Medicine, Massachusetts General Hospital, Harvard Medical 
School, Boston.)
TABLE 42.1 Flexor Tendons of the Hand
Flexor Tendon Insertion Innervation Function/Physical Examination
Flexor Carpi Radialis Second and third metacarpal bases Median N. Flexion and radial deviation at the wrist
Flexor Carpi Ulnaris Hook of hamate and base of fifth 
metacarpal
Ulnar N. Branches Flexion and ulnar deviation at the wrist
Palmaris Longus Palmar aponeurosis and flexor 
retinaculum
Median N. Flexion at wrist, palpable tendon if present
Flexor Digitorum Profundus (FDP) Base of distal phalanges Median N. and Ulnar N. Flexion of MCP, DIP, and PIP joints (Isolatedexamination by flexing DIP with other joints held 
in extension)
Flexor Digitorum Superficialis (FDS) Base of proximal phalanges Median N. Flexion of MCP and PIP joints (Examine by flexing 
PIP with MCP held in neutral position)
Flexor Pollicis Longus Base of distal phalanx of thumb Median N. Flexion at MCP and IP joints of thumb
466 PART II Trauma
artery and the radialis indicis artery arise from the deep palmar 
arch. The deep palmar arch of the radial artery continues to 
loop deep within the volar surface of the hand and anastomoses 
with the ulnar artery. The superficial palmar arch of the radial 
artery courses superficially over the metacarpals where it also 
anastomoses with the ulnar artery. In doing so, the superficial 
palmar arch gives rise to the palmar digital arteries which further 
branch to supply the fingers distally from the radial and ulnar 
aspects of each digit (Fig. 42.13).
The ulnar artery enters the hand superficial to the flexor retinac-
ulum through the wrist via the Guyon canal, a space created by the 
pisiform and palmar carpal ligament. Immediately distal to the Guyon 
canal, the ulnar artery branches into the large superficial palmar arch. 
These arches form collaterals with the deep palmar arches of the radial 
artery and perfuse every digit in almost all patients. The collateral arte-
rial system within the hand and digits allow for continued perfusion if 
either the radial or ulnar arterial flow is impaired. Testing for perfu-
sion via the radial and ulnar arteries individually can be accomplished 
through the Allen test (Fig. 42.14).
There are times when an Allen test cannot be performed due to the 
patient’s level of consciousness or due to other injuries. In those situ-
ations, simple palpation or use of Doppler ultrasound to assess blood 
flow to the hand through the radial and ulnar arteries at the wrist will 
suffice. It is important to make sure backflow through the palmar arch 
does not give the examiner a false- positive result of a patent artery. 
Thus, the ulnar artery should be compressed at the wrist when check-
ing the patency of the radial artery when the Allen test cannot be done. 
Additionally, there may be significant arterial injury in the absence of 
heavy bleeding as the injured vessel may become compressed by sur-
rounding edematous tissue.
Venous and Lymphatic System
The deep veins of the hand travel in a neurovascular bundle along with 
the arteries of the hand. The dorsum of the hand contains the lymphatic 
system within the loose subcutaneous tissue. The lymphatics eventually 
drain into the forearm via the cephalic and basilic veins. The presence 
of lymphatics and loose subcutaneous tissue results in greater swelling 
on the dorsum (versus volar) aspect of the hand with infections.
Flexor retinaculum
Flexor digitorum
superficialis tendon
Palmar ligament
Synovial sheath
Synovial sheath
Flexor digitorum
profundus tendon
Fibrous digital sheaths
Synovial sheath of
flexor pollicis
longus tendon
Deep transverse
metacarpal ligament
Fig. 42.11 The synovial sheaths of the hand and their relationship to the flexor tendons. (Drake RL, Vogl AW, 
Mitchell A. Upper limb. In: Gray’s Anatomy for Students, ed 4. Philadelphia: Elsevier; 2020:671-821.)
467CHAPTER 42 Hand Injuries
Innervation and Sensory Systems
The median nerve enters the hand via the carpal tunnel. It is respon-
sible for sensation of the radial two- thirds of the volar surface of the 
hand as well as the flexor surface of fingers 1 through 3 and the radial 
half of the fourth (ring) finger (Fig. 42.15). The motor branch of the 
median nerve innervates five intrinsic muscles of the hand including 
the thenar muscles and two of the lumbricals. The extrinsic muscles of 
the hand innervated by the median nerve include the flexor tendons to 
the radial three digits and FCR.
The ulnar nerve supplies sensation to the ulnar one- third of the 
hand at both the volar and dorsal surfaces. It is also responsible for 
sensation of the fifth finger and the ulnar half of the fourth finger. The 
ulnar nerve is responsible for the extrinsic motor function of the flexor 
carpi ulnaris (FCU) and the flexor digitorum profundus (FDP) tendons 
of the fourth and fifth digits. It also innervates the remaining intrinsic 
muscles of the hand and divides into a volar and dorsal branch at the 
wrist. The volar branch, along with the ulnar artery, enters the palm 
through the Guyon canal. It is responsible for movement of muscles 
of the hypothenar eminence, interosseus muscles, and the lumbricals 
of the fourth and fifth fingers. The deep branch innervates the adduc-
tor pollicis. The ulnar nerve’s motor innervation of the fourth and fifth 
digits is largely responsible for grip power and injury can significantly 
alter normal use of the hand.
The radial nerve contains superficial and deep branches and pro-
vides sensation to the radial two- thirds of the hand on the dorsal sur-
face excluding the fingertips. There are no motor function branches for 
the radial nerve within the hand, though its innervation of the dorsal 
forearm leads to hand function including extension of the wrist (exten-
sor carpi radialis longus) as well as other extensor tendons (extensor 
digitorum communis, extensor digiti quinti proprius, extensor pollicis 
longus and brevis).
The median, ulnar, and radial nerves each give rise to common 
digital nerves which further divide into lateral and medial branches 
on respective sides of each digit (Fig. 42.16). There are four individual 
digital nerves supplying sensation to each digit. The dorsal branch of 
these nerves run along the dorsal edge of the line made by the flexor 
crease to the tip of the finger.
Sensation of the hand should be tested in all hand injuries, particu-
larly in patients with suspected nerve injury. Two- point discrimination 
is most precise in testing for sensation at the digits and may be tested 
by using the blunt ends of a paperclip (Fig. 42.17). Sensation is deemed 
intact if a patient is able to distinguish between one and two points to 
a distance of 5 mm.
For rapid examination of the motor and sensory functions of the 
hand, a few simple tests can be performed. One simple test for motor 
function of the radial, ulnar, and median nerve is to have the patient 
make an “OK” sign with their thumb and index finger (testing the 
median nerve), while dorsiflexing the wrist (radial nerve) and spread-
ing/abducting the third, fourth, and fifth fingers (ulnar nerve). For 
general sensory examination, a clinician can test the finger tufts of the 
index finger (median nerve), the little finger (ulnar nerve), and the 
dorsum of the proximal phalanx of the thumb (radial nerve) with two- 
point discrimination. Simply being able to differentiate between sharp 
and dull is often enough to assess sensation. This can be done expe-
ditiously at the bedside by using a broken tongue blade or 18- gauge 
needle.
If there is any concern about the function or sensation, more specific 
testing should be focused on a specific nerve and digit. It is important 
to identify where the nerves are injured. For example, if the ulnar nerve 
is severed in the forearm, the extrinsic muscles will not function and 
the fourth and fifth fingers will not flex. If tendons are lacerated in the 
hand, there may be similar dysfunctional results.
Regional Blocks
Digital Block
The digital block is commonly used for wound repair or incision and 
drainage of the affected finger. The volar and dorsal nerves of the finger 
course along the lateral edges of the fingers and allow for easy access 
to regional anesthesia (Fig. 42.18). Lidocaine 1% or 2% is commonly 
used for digital blocks, though bupivacaine may be used if a longer 
period of anesthesia is desired. Despite the lack of evidence, many peo-
ple advocate against the use of epinephrine in anesthetic preparations 
given the theoretical potential for vascular compromise secondary to 
arterial constriction. However, a previousprospective study of over 
3000 patients and a recent meta- analysis found no harm in the use of 
epinephrine for digital blocks in healthy patients.4 Lidocaine with epi-
nephrine has the added benefit of a longer period of anesthesia and 
potentiating hemostasis. Lidocaine with epinephrine should be used at 
the physician’s discretion, though we uphold its safety in patients with-
out severe vascular disease based on the current literature.
There are multiple ways to perform a digital block, though a com-
mon method is using the web spaces on each side of the digit being 
anesthetized. First, the skin at the locations of needle insertion should 
be adequately cleansed. The hand should be positioned with the pal-
mar surface facing downward. A small needle is inserted into the skin 
at the distal webspace on the dorsal surface of the finger along the 
edge of the phalanx. The dorsal nerve runs under the skin alongside a 
A5
C3
A4
C2
A3
C1
A2
A1
Fig. 42.12 Normal anatomy of the flexor pulley system with lateral and 
volar views. A2 and A4 are the narrowest points. (From: Morrison WB, 
Sanders TG. Problem Solving in Musculoskeletal Imaging. Philadelphia: 
Mosby; 2008:484.)
Proper digital artery
Common digital artery
Deep palmar arch
Superficial palmar branch
of radial artery
Princeps pollicis artery
Superficial palmar arch
Deep palmar branch
of ulnar artery
Radial artery
Ulnar artery
FCU
FCR
BR
Fig. 42.13 Arterial anatomy of the hand. BR: brachioradialis; FCR: flexor carpi radialis; FCU: flexor carpi 
ulnaris. (From: Chhabra AB. Wrist and hand. In: Miller MD, Chhabra AB, Hurwitz S, et al,. eds. Orthopaedic 
Surgical Approaches, Philadelphia: Saunders; 2008:161.)
A B
C
Fig. 42.14 Demonstration of the Allen test to individually evaluate ulnar and radial arterial flow. (A) Both arter-
ies are compressed with the patient’s hand in a fist. (B) Pressure over the ulnar artery is released while com-
pression on the radial artery is maintained. (C) Capillary perfusion is assessed and then the test is repeated by 
reversing which vessel is compressed. (Grasau B, Jones CM, Murphy MS. Use of diagnostic modalities for 
assessing upper extremity vascular pathology. Hand Clinic. 2015;31(1):1-12.)
469CHAPTER 42 Hand Injuries
digital artery, so the operator should first aspirate to ensure there is no 
intravascular injection. A volume of 0.5 to 1 mL of local anesthetic is 
injected, and without withdrawing, the needle should be advanced into 
the volar side of the bony phalanx where an additional 0.5 to 1 mL of 
the anesthetic is injected. The same process should be repeated on the 
opposite side of the digit to ensure that all four nerves are anesthetized.
While it is possible to obtain appropriate anesthesia with local infil-
tration of anesthetic, there are several advantages of a digital block 
over local infiltration.5 First, there are fewer injection sites, ideally 
resulting in less pain for the patient. Second, local infiltration creates 
edema along the wound margins leading to greater tissue distortion 
and greater difficulty in obtaining appropriate wound approximation, 
which can be avoided with a digital block. Third, less anesthetic is 
needed for most regional procedures.
Metacarpal and Transthecal Blocks
If more proximal anesthesia is desired, a metacarpal block may be per-
formed. This block may be administered on either the dorsal or palmar 
side of the hand, though the dorsal approach is often preferred due to 
thicker skin on the volar surface as well as greater innervation, making 
penetration more difficult and less tolerable.
For the palmar approach, the needle is inserted directly over the 
metacarpal head. When the needle is subcutaneous, it is directed to 
one side of the metacarpal. While advancing the needle approximately 
1 cm, aspiration is performed to ensure the needle is not in a vessel, 
and approximately 3 mL of local anesthetic is injected. The needle is 
then partially withdrawn and redirected to the other side of the meta-
carpal and the procedure is repeated. With a transthecal digital block, 
the needle is similarly inserted into the palmar surface, though more 
proximally at the distal palmar crease. At a 45- degree angle, the needle 
is advanced directly into the flexor tendon sheath. If the sheath has 
been entered, there should be little to no resistance with injection of 
anesthetic. If there is significant resistance, the needle has likely entered 
the tendon and it should be gradually withdrawn.
The dorsal approach is similar to the traditional digital block. The 
needle is inserted along one side of the dorsal surface of the metacarpal 
approximately 1 cm proximal to the MCP joint. The needle is advanced 
until the palmar aponeurosis or the volar edge of the metacarpal where 
approximately 2 mL of anesthetic is injected. While withdrawing the 
needle, an additional 1 mL of anesthetic is injected along the tract. The 
procedure is then repeated on the dorsal surface of the opposite side of 
the same metacarpal.
Wrist Blocks
As discussed previously, the radial, median, and ulnar nerves supply 
sensation to the hand. Each nerve can be blocked individually to anes-
thetize its respective dermatome. Traditionally, these nerves have been 
blocked using anatomic landmarks at the wrist, though newer methods 
involve ultrasound- guided blocks at the forearm. These nerve blocks 
have the advantage of requiring less anesthetic volume and decreased 
need for opiate analgesia.6 The goal is to inject around the nerve but not 
directly into the nerve. If the nerve is inadvertently injected the patient 
may feel an uncomfortable “shock- like” sensation.
Radial Nerve Block. The radial artery at the volar surface of the 
wrist is palpated. Immediately lateral (radial) to this region, after 
aspirating, approximately 2 to 5 mL of local anesthetic is injected.
Median Nerve Block. The tendon of the flexor carpi radialis at the 
volar surface of the wrist is palpated. The needle is inserted over the 
median nerve which is 1 cm ulnar from the flexor carpi radialis or 
between this tendon and the palmaris longus. The needle is advanced 
into the flexor retinaculum, where a “pop” may be felt, and the patient 
may complain of paresthesias. To avoid intraneural injection, the 
needle should be withdrawn a few millimeters where 3 to 5 mL of 
anesthetic agent is then injected. Due to baseline constriction at the 
flexor retinaculum, this procedure is a relative contraindication in 
patients with carpal tunnel syndrome.
Ulnar Nerve Block. The needle should be inserted between the ulnar 
artery and the flexor carpi ulnaris tendon and advanced approximately 
1 cm. If the patient complains of paresthesia, the needle should be 
withdrawn a few millimeters with aspiration performed to ensure the 
needle is not in a blood vessel. Approximately 5 mL of anesthetic is 
then injected.
Radial nerve
Median nerve
Ulnar
nerve
Fig. 42.15 Sensory distribution at the hand for radial, median, and ulnar 
nerves. (Murphy- Lavoie H, LeGros TL. Local and regional anesthesia. In: 
Adams JG, Barton ED, Collings, J, et al. Emergency Medicine: Clinical 
Essentials, ed 2. Philadelphia: Elsevier; 2013:1578-1586.)
Fig. 42.16 The nerve, artery and vein bundle of the finger can be approx-
imated on the skin by aligning the flexion creases of each joint. Avoiding 
this bundle when making an incision is desired. (Courtesy Clara Bihn, 
Butler University)
Fig. 42.17 Demonstration of two- point discrimination testing. (Jobe 
MT. Nerve injuries at the level of the hand and wrist. In: Azar F, Canale 
ST, Beaty J. Campbell’s Operative Orthopaedics, ed 13. Philadelphia: 
Elsevier; 2016:3462-3477.)
470 PART II Trauma
Splinting
Splinting of hand injuries must take into account both the bony struc-
tures and the tendons that need to be protected. If a hand requires 
splinting for more than a day, the splint should maximize the length 
of the extensor tendons and the hand should be placed ina functional 
position. Specific positioning is needed for splints on patients with ten-
don or ligamentous injuries or certain fractures. The neutral position 
for general fractures of the hand or fingers is a volar splint with the 
wrist at 20 to 30 degrees extension, MCP at 70 to 90 degrees flexion, 
and the PIP and DIP kept in extension. This is also known as intrin-
sic plus position (Fig. 42.19). Appropriate positioning with splinting is 
critical because incorrect splinting is one the most common reasons for 
chronic hand stiffness after an injury.
Ring Removal
Early ring removal from an edematous finger is important because the 
ring acts as a tourniquet, causing further restriction of venous return 
and eventually arterial compromise if removal is delayed. Initial edema 
may occur secondary to a number of conditions such as infections, 
allergic reactions, fractures, arthritis, weight gain, or burns.
If the initial examination does not show signs of neurovascu-
lar compromise or severe constriction, the examiner may attempt 
removing the ring manually by lubricating the finger and then 
applying distal traction on the ring making twisting movements. 
The finger should be iced or elevated prior to this procedure to 
reduce swelling. If this is unsuccessful, there are other methods of 
ring removal.
In the absence of neurovascular compromise, deep ring erosion, 
or open wound, one may attempt less invasive methods such as the 
ring- wrap method, rubber- band method, or surgical glove method for 
ring removal. For the surgical glove method, the finger of a rubber or 
latex glove is cut off and placed over the patient’s affected finger. The 
proximal end of the glove should be pulled underneath the ring (Fig. 
42.20). Lubricant may be used to assist with this step. The proximal 
end of the glove should then be pulled back over the ring. Distal trac-
tion and twisting should be performed to advance the ring distally and 
assist in ring removal.
A similar technique has been described in the literature utilizing 
two rubber bands. These two rubber bands are advanced under the 
ring using a hemostat and are then used to pull distal traction on the 
ring for removal.7
In instances of deep ring erosion, an open wound, or obvious neu-
rovascular compromise, prompt ring removal is essential. In these 
cases, we recommend use of a ring- cutting device if available (Fig. 
42.21).8 Most ring cutters have a circular blade and a hook or eleva-
tor. The hook should be slid under the ring. This serves as a barrier to 
the blade deep to the ring. The handle should be gripped, bringing the 
saw to the ring, where the grinding process through the ring can be 
performed. The ring may get hot during this process, and the patient 
may sustain a burn, so taking breaks approximately every 30 seconds 
is recommended. When the ring is cut, hemostats can aid in separat-
ing the two cut ends to remove the ring. Following ring removal, the 
patient should be monitored and examined for any signs of laceration 
or neurovascular compromise.
SPECIFIC HAND INJURIES
Phalanx and Metacarpal Fractures
Clinical Features
The hand is the most common location for fractures in the body. 
Specifically, phalanx and metacarpal fractures account for 10% of all 
fractures and the distal phalanx is the most common location.9 These 
fractures are most common in young men and nearly a quarter occur 
during a sporting event. The type of fracture is classified based on 
Proper palmar digital nn.
Dorsal digital nn.
Middle phalanx
Proper palmar digital a.
Dorsal digital v.
Fig. 42.18 Demonstration of digital and metacarpal nerve block with needle inserted at appropriate land-
marks. (Waldman, SD. Atlas of Interventional Pain Management, ed 4. Philadelphia: Elsevier; 2015:275-278.)
471CHAPTER 42 Hand Injuries
Forearm Volar “Cockup” Splint
Burkhalter:
Forearm Sugar Tong:
Thumb Spica:
Soft tissue hand/wrist injuries
Most wrist, 2nd-5th metacarpal fractures (for transport)
Sandwich splint add a dorsal splint stability
Not for distal radius or ulnar fractures–forearm
 supination/pronation still possible!
Metacarpal neck fractures, MCP dislocations
Volar slab 30 degrees wrist extension
Dorsal slab with 90 degrees metacarpal flexion
Ulnar Gutter:
4th-5th metacarpal, MCP joint,
Prox/Middle
 P = phalangeal sprains/fractures
Radial Gutter:
Sprains/fractures
2nd-3rd digital metacarpal, MCP Joint,
Proximal middle phalanges
Finger Splints:
Stable middle, distal phalanx fractures
PIP sprains: dynamic splint (buddy taping)
Distal radius and ulnar fracture
Prevents forearm pronation/supination
Scaphoid, thumb MCP
De Quervain tenosynovitis
Wine glass position immobilization of 1st MCP
Allows thumb DIP free to oppose
Splints
Which to Consider and When?
Fig. 42.19 Various types of splints for various hand injuries. Most hand injuries should be splinted in neutral 
(functional) position with the wrist slightly extended at 30 degrees, the MCP joints flexed to 90 degrees, and 
the PIP and DIP joints held in extension. (Courtesy Dr. D.A. Stearns, Department of Emergency Medicine, 
Massachusetts General Hospital, Harvard Medical School, Boston.)
A B C
Fig. 42.20 (A) The glove is pulled under the ring using hemostats. (B and C) The glove is moved over the 
ring, thereby removing it from the finger. (Haynes JH, Haynes AT, Hines TR. Ring removal from an edematous 
finger. In: Pfenninger JL, Fowler GC. Pfenninger and Fowler’s Procedures for Primary Care, ed 3. Saunders; 
2010:1320-1322)
location and stability. Common mechanisms of injury are with direct, 
crushing, penetrating, or blunt trauma.
Differential Diagnoses
The differential diagnoses for phalanx and metacarpal fractures are exten-
sive and include tendon, joint- space, and ligamentous injuries (Table 42.2).
Diagnostic Testing
A standard x- ray series of the hand, including a PA, lateral, and oblique 
film, is sufficient imaging to detect most phalanx and metacarpal frac-
tures. Ultrasound is another acute imaging modality, though it is infe-
rior to x- ray imaging as previously described.
472 PART II Trauma
Management
Transverse fractures are generally stable while oblique, intra- 
articular, comminuted fractures, and fractures associated with dis-
locations tend to be unstable. Most fractures can be managed with 
appropriate splinting (see Fig. 42.19), but there are certain situations 
which do require emergent surgical consultation, including open 
fractures, partial or complete amputations, displaced intra- articular 
fractures, and fractures that do not maintain reduction. Additionally, 
spiral, rotated, and oblique fractures tend to be unstable and require 
outpatient follow- up with a hand specialist for possible surgical fixa-
tion. Patients who have fractures that are amenable to closed reduc-
tion can generally tolerate the procedure with adequate anesthesia 
via hematoma block (metacarpal fractures) or digital block (phalanx 
fractures).
Although splinting varies based on individual clinical scenarios, 
there are certain principles for immobilization for fractures of the 
hand. For most phalangeal fractures, a long finger splint is sufficient, 
though in cases of instability and significant tendon and ligamentous 
injury, proximal immobilization at the wrist may be necessary. Fur-
ther stabilization of phalanx fractures can be accomplished by dynamic 
splinting or “buddy- taping” the splinted injured finger to the adjacent 
uninjured finger. For metacarpal fractures and phalanx fractures with 
accompanying instability, a radial gutter splint may be used for frac-
tures of the index and middle fingers. Similarly, an ulnar gutter splint 
may be used for fractures of the ring and little fingers. Fingers adjacent 
to the injured finger should be included in the splint. A thumb spica or 
radial gutter splint should be used for thumb fractures. We recommend 
a low threshold for splinting in skeletally immature pediatric patients 
if there is a high suspicion for fracturedespite negative x- rays. Loss 
of motion, malunion, and nonunion are common complications for 
untreated fractures.
Phalanx Fractures
Distal Phalanx Fractures
Clinical Features
Distal phalanx fractures result from a direct blow to the dorsal surface 
of the finger or axial force to the extended fingertip. They are further 
classified into tuft, shaft, base, and intra- articular fractures (Fig. 42.22).
Tuft fractures generally occur secondary to a crush injury. These 
fractures are usually stable due to presence of the nail plate and pulp. 
They often involve injury to the distal phalanx with laceration to the 
nail bed or pulp and can be accompanied by subungual hematoma (see 
later).
Fig. 42.21 Mechanical ring cutter. (Khodaee M, Tirabassi J. The hand- 
powered ring cutter: a useful tool in your wilderness medical bag. Wil-
derness Environ Med. 2015;26(3):441-442.)
TABLE 42.2 Differential Diagnoses 
for Hand Injuries
Location of Injury Differential Diagnosis
Distal phalanx/DIP 
joint
Tuft, shaft, or avulsion fracture
Seymour fracture
Crush injury
Nail bed injury
Subungual hematoma
Mallet finger (dorsal) or jersey finger (volar)
DIP dislocation or subluxation
Collateral ligament injury
Extensor digitorum communis injury
FDP tendon injury
Middle phalanx/PIP 
joint
Head, neck, shaft, or base fracture
Dorsal, volar, or lateral PIP dislocation or subluxation
Volar plate or collateral ligament injury
Central slip (extensor) injury
FDP or FDS tendon injury
Proximal phalanx/MCP 
joint
Head, neck, shaft, or base fracture
Dorsal, volar, or lateral MCP dislocation or subluxation
Volar plate or collateral ligament injury
Trigger finger
Clenched fist (“fight bite”) injury
Extensor complex injury
FDP or FDS tendon injury
Metacarpal/CMC joint Head, neck, shaft, or base fracture
Dorsal or volar CMC dislocation
Ulnar nerve injury
Extensor complex injury
FDP or FDS tendon injury
Thumb distal phalanx/
IP joint
Tuft, shaft, or avulsion fracture
Crush injury
Nail bed injury/subungual hematoma
Mallet thumb
IP joint dislocation or subluxation
Volar plate or collateral ligament injury
Extensor pollicis longus tendon injury
Thumb proximal 
phalanx/MCP joint
Head, neck, shaft, or avulsion fracture
Ulnar collateral ligament injury (skier’s or 
gamekeeper’s thumb)
Radial collateral ligament injury
Thumb metacarpal/
CMC joint
Head, neck, or shaft fracture
Base (Bennet or Rolando) fracture
CMC joint dislocation or subluxation
Oblique CMC ligament injury
Abductor pollicis longus tendon injury
473CHAPTER 42 Hand Injuries
Fractures of the shaft are divided into transverse and longitudinal. 
Transverse fractures are generally stable and longitudinal fractures are 
unstable.
Fractures occurring at the base of the distal phalanx are usually 
unstable and intra- articular. These appear as avulsion fractures on 
x- ray and often are sports- related injuries. A common mechanism is 
an axial loading force on an extended distal phalanx resulting in force-
ful flexion or hyperextension at the DIP joint. Avulsion fractures at the 
base are further divided into dorsal injuries (e.g., mallet finger) and 
volar injuries (e.g., jersey finger). Mallet finger will present with inabil-
ity to extend the distal phalanx at the DIP joint. Radiographs often 
show an avulsion fracture at the dorsal base of the DIP, though there 
may be an isolated distal extensor tendon rupture. In contrast, a jersey 
finger will present with inability to flex the distal phalanx at the DIP 
joint. X- rays may show an avulsion fracture at the volar base of the 
DIP, though there may be isolated rupture of the flexor digitorum pro-
fundus tendon.
The Seymour fracture, which is a transverse fracture of the distal 
phalanx involving the physis, occurs in the pediatric population.10 This 
includes Salter- Harris type I and II fractures and typically involves a 
crush injury mechanism. It frequently occurs when a child gets a fin-
ger stuck in a door or folding chair. On exam, there will be exquisite 
tenderness at the distal phalanx and evidence of an associated nail bed 
injury, such as avulsion of the nail at the germinal matrix. This is con-
sidered an open fracture.
Differential Diagnoses
When considering a fracture of the distal phalanx, one should be 
mindful of other potential injuries or associated injuries to the distal 
phalanx. These include distal amputations, nail bed injuries, subungual 
hematomas, FDP tendon injuries, extensor mechanism injuries, collat-
eral ligament injuries, and DIP dislocations or subluxations.
Diagnostic Testing
Standard x- ray imaging of the affected finger should be obtained if 
there is pain, swelling, tenderness, or loss of functional integrity fol-
lowing injury to the distal phalanx. Any separation, displacement, or 
angulation should be identified.
Management
Because most tuft fractures are stable and non- displaced, they are typ-
ically treated conservatively with analgesia and splinting. Splinting 
involves 2 to 4 weeks of protection with a finger cage splint or a molded 
aluminum splint that encloses the distal phalanx, though allowing for 
movement at the DIP. Hand specialist consultation is required for dis-
placed fractures that are irreducible as well as for open fractures.
While antibiotics have traditionally been recommended for tuft 
fractures associated with nail bed or soft- tissue injuries, a recent meta- 
analysis involving 4 RCTs assessing rates of superficial infection and 
osteomyelitis in open distal phalanx fractures found no difference in 
rates of superficial infection and osteomyelitis in patients receiving 
antibiotics versus those who did not.11 While there is strong evidence 
to support the use of antibiotics for open fractures elsewhere in the 
body, distal phalanx fractures are different in that most are secondary 
to deep lacerations or a crush injury where there is less periosteal strip-
ping. The study suggests that the focus of treatment for open fractures 
should be on prompt irrigation and early débridement, rather than 
prophylactic antibiotics.
Transverse fractures at the shaft of the distal phalanx are usu-
ally non- displaced and require only protective splinting for 2 weeks. 
Reduction of displaced fractures should be attempted in the emergency 
department, though if closed manipulation is unsuccessful or if the 
fracture remains unstable, the distal phalanx should be splinted, and 
the patient referred to a hand specialist for pinning.
Longitudinal fractures should be splinted from the middle to distal 
phalanx, leaving the PIP joint mobile. Immobilization should be for 
3 to 4 weeks followed by passive range- of- motion exercises until the 
finger is pain- free.
Almost all mallet finger injuries should be treated conservatively 
initially with splinting. The DIP joint is immobilized with splinting 
in neutral position or slight hyperextension continuously for 6 weeks. 
Compliance is critical. If the joint is flexed at any point during the 
6- week splinting period, the course must be restarted. Stack splints or 
aluminum foam splints may be used (Fig. 42.23). Patients should be 
referred to a hand specialist as patients with a fracture involving one 
third or greater of the articular surface and those who fail conserva-
tive treatment are considered for surgical management by the hand 
specialist.
Avulsion fractures at the volar base of the distal phalanx may be 
treated conservatively with a dorsal or volar splint if there is some DIP 
joint flexion present. This is accomplished by immobilizing only the 
DIP joint in slight flexion (5–10 degrees) for at least 6 weeks. If there 
is no retained ability to flex the DIP joint, assume rupture of the FDP 
tendon (jersey finger) and refer the patient for surgical management. In 
the meantime, the finger should be immobilized in a splint that incor-
porates the wrist with the finger maintained in flexion.
Pediatric patients with Seymour fractures (Salter- Harris fracture of 
the finger in which the nailcomes out from the nail fold) should ideally 
have repair performed in the emergency department. Irrigation, reduc-
tion, nail bed repair, and laceration repair may be performed by the 
emergency physician. If the fracture can be reduced and closed well, 
the patient can follow up in 7 to 10 days. If there is difficulty or insta-
bility to the injury after treatment in the ED, then the patient should be 
seen by a hand specialist within 24 hours. As these are open fractures, 
antibiotics (i.e., cephalexin 50 mg/kg/day divided q6 hours for 7–10 
days) should be initiated. For repair of Seymour fracture injuries, it is 
important to save the fingernail, if possible, by carefully trimming a 
small amount of the proximal nail plate that is exposed and inserting it 
back underneath the eponychial fold with a mattress suture. With this, 
an acceptable reduction of the Salter- Harris fracture is obtained. One 
should avoid overdissection of nail bed from the nail plate as this may 
cause further damage. Repair of the nail bed with 6-0 or 7-0 chromic 
absorbable suture is done when the nail bed injury is visible. Careful 
reduction, nail bed repair, and fixation of the distal phalanx in slight 
hyperextension have been shown to improve outcomes and reduce the 
incidence of nail growth disturbance, growth plate damage, and long- 
term loss of flexor tendon function (Fig. 42.24 and 42.25).
Middle Phalanx Fractures
Clinical Features
Middle phalanx fractures are classified based on location, defor-
mity, and stability. They may involve the head, neck, shaft, or base. 
A B C
Fig. 42.22 Types of distal phalanx fractures. (A) Longitudinal, (B) trans-
verse, and (C) comminuted. (Petering, RC. Finger fractures. In: Eiff MP, 
Hatch R, Higgins MK. Fracture Management for Primary Care. Ed 3 
updated. Philadelphia: Elsevier Saunders; 2018:36-62.)
474 PART II Trauma
Deformity and displacement are dependent on the location of the 
fracture and result from the dynamic forces of the flexor and exten-
sor tendons involved. The flexor digitorum superficialis divides and 
inserts along the volar surface while the extensor tendon (central 
slip) inserts at the proximal base (Fig. 42.26). As a result, fractures 
of the distal middle phalanx usually result in volar angulation, while 
proximal fractures near the base tend to result in dorsal angulation9 
(Fig. 42.27).
Fractures at the base include intra- articular types which appear on 
x- ray as avulsion fractures and are classified based on their location: 
condylar, volar, and dorsal. There is also the possibility of complete dis-
ruption of the articular surface (pilon fracture) in which multiple ten-
dons are involved with instability in all directions.
Differential Diagnoses
One should consider volar plate, collateral ligament, central slip, FDP 
tendon, and FDS tendon injuries when assessing for a possible frac-
ture. Associated IP joint dislocations or subluxations should also be 
considered.
Diagnostic Testing
Standard x- ray imaging of the digit is sufficient to identify most clini-
cally significant fractures.
Management
Stable non- displaced transverse fractures can be treated with 
dynamic splinting (Fig. 42.28) and by buddy taping to an adjacent 
uninjured digit. Dynamic splinting offers the advantage of provid-
ing some degree of stability while preventing joint stiffness. Immo-
bilization should be for 2 to 3 weeks followed by range- of- motion 
exercises.
Transverse shaft fractures that are angulated, shortened, or have 
rotational deformity require surgical referral. Displaced transverse 
fractures typically have volar angulation and require closed reduction 
which can be performed with longitudinal traction followed by flexion 
of the distal fragment to align with the proximal fragment. Oblique, 
spiral, and comminuted fractures, in addition to unstable transverse 
A B
Fig. 42.23 Thumb stack splint immobilizing the IP joint as seen in (A) AP and (B) lateral views. (Courtesy of 
Mary Jo Wagner, MD, FACEP; Central Michigan University COM.)
A B
Fig. 42.24 Seymour fracture presentation. (A) Open fracture of the 
distal phalanx of the ring finger together with nail avulsion. (B) X- ray 
demonstrating open juxta- epiphyseal fracture of the distal phalanx. 
(Metcalfe D, Aquilina AL, Hedley HM. Prophylactic antibiotics in open 
distal phalanx fractures: systematic review and meta- analysis. J Hand 
Surg (European vol). 2016;41(4):423-430.)
Fig. 42.25 Seymour fracture illustration demonstrating a lateral view 
with open avulsion fracture at the distal phalanx base and nail bed avul-
sion. (Modified from: Metcalfe D, Aquilina AL, Hedley HM. Prophylactic 
antibiotics in open distal phalanx fractures: systematic review and meta- 
analysis. J Hand Surg (European vol). 2016;41(4):423-430.)
475CHAPTER 42 Hand Injuries
fractures, should be immobilized to the level of the wrist with an ulnar 
or radial gutter splint to eliminate deforming tendon forces.
Fractures of the base that include 50% or greater of the articular 
surface or fractures requiring greater than 30 degrees of flexion to 
maintain reduction are almost always unstable and require surgical 
management.12 Non- displaced stable fractures involving 20% or less of 
the articular surface may be managed by extension splinting.
Proximal Phalanx Fractures
Clinical Features
Fractures at the proximal phalanx may result from a direct blow, forc-
ible hyperextension, or rotational forces and are classified based on 
location: head, neck, shaft, or base. Fractures of the head that are condy-
lar or involve displacement are considered unstable. Similar to middle 
phalanx fractures, fractures at the shaft are prone to opposing tendon 
forces. Displaced fractures tend to have a visible apex volar deformity 
and involve the proximal fragment in flexion (interossei) and the distal 
fragment in extension (central slip)9 (Fig. 42.29).
Differential Diagnoses
In addition to fractures, other injuries around the proximal phalanx 
should be considered including injuries to the volar plate, collateral 
ligaments, extensor mechanism, FDP tendon, and FDS tendon. For 
proximal injuries, the MCP joint should be assessed for evidence of 
clenched fist (“fight bite”) injuries, trigger finger, and dislocations or 
subluxations of the MCP joint.
Diagnostic Testing
Standard x- ray imaging is sufficient to identify most proximal phalanx 
fractures.
Management
Non- displaced transverse fractures, and other stable fractures of the 
proximal phalanx, may be managed nonoperatively by splinting.13 
Splinting should be performed with a dorsal aluminum padded splint 
extending from the metacarpal to the middle phalanx with the MCP 
joint at 70 to 90 degrees of flexion and the PIP joint at 30 degrees of 
flexion. Displaced fractures should be reduced and splinted. Similar 
to stable non- displaced fractures, a dorsal splint should be placed with 
the MCP and PIP in slight flexion. Further stabilization at the wrist 
with a radial or ulnar gutter splint should be added. Oblique, spiral, 
angulated, and unstable intra- articular fractures should be splinted 
similarly, though they also require outpatient follow- up with a hand 
specialist for surgical repair to be performed within one week.
Unicondylar or bicondylar fractures of the head of the proximal 
phalanx are considered unstable even if nondisplaced. These types of 
fractures often require surgical management as displacement often 
occurs with splinting alone. The patient should have urgent outpatient 
follow- up with a hand specialist so that surgical fixation could occur 
within one week.
PIP flexionA
B PIP extension
MCP
Central slip
PIP
Lateral band
Allows DIP flexion
MCP
Central slip
PIP
Lateral band
DIP
extends
TRL pulls lateral
bands volarly
ORL relaxed
TRL limits dorsal
translation of lateral bands
ORL
tightens
Fig. 42.26 (A) With PIP flexion, the transverse retinacular ligament 
(TRL) pulls the lateral bands into the volar position, while the obliqueretinacular ligament (ORL) relaxes and helps coordinate DIP flexion. (B) 
With the PIP in extension, the TRL prevents PIP hyperextension by lim-
iting the dorsal displacement of the lateral bands while the ORL tight-
ens (permitting coordinated DIP extension). (From: Elzinga K, Chung 
KC. managing swan neck and boutonniere deformities. Clin Plast Surg. 
2019;46(3):329-337.)
A
B
Fig. 42.27 Illustration of deforming forces acting on middle phalanx 
fractures (A) Transverse fractures proximal to the FDS insertion angu-
late dorsally. (B) Fractures distal to the FDS insertion angulate in the 
volar direction. (From: Capo JT, Hastings H II. Metacarpal and phalan-
geal fractures in athletes. Clin Sports Med. 1998;17(3):508. Fig. 15.)
Fig. 42.28 Dynamic splint demonstrated in a patient. (Hays PL, Roz-
ental TD. Rehabilitative strategies following hand fractures. Hand Clin. 
2013;29(4):585-600. Fig. 7.)
476 PART II Trauma
Metacarpal Fractures
Clinical Features
Patients with metacarpal fractures generally present after a direct blow 
to the dorsum of the hand or an axial loading force over the metacarpal 
head. The hand should be thoroughly examined for tendon integrity, 
deformity, and any evidence of open fracture or fight bite. Like phalanx 
fractures, metacarpal fractures are classified based on location: head, 
neck, shaft, and base.
Fractures of the metacarpal head are rare and usually occur sec-
ondary to a direct or crushing force. They often are intra- articular and 
accompanied by an extensor tendon injury.
The neck is the most common location for metacarpal fractures 
because the bone is weakest at this location. These fractures commonly 
occur secondary to punching a firm object, hence the term boxer’s frac-
ture given to fractures at the neck of the fifth metacarpal. Displacement 
is usually apex dorsal angulation owing to forces from the extrinsic 
flexor tendons which flex the distal fragment (Fig. 42.30). The car-
pometacarpal (CMC) joints inherently have greater stability and less 
range of motion at digits 2 and 3 relative to digits 4 and 5. Greater range 
of motion at the ulnar aspect of the hand, especially in flexion, enables 
a powerful grip. It also accounts for a greater degree of tolerable dis-
placement in the ulnar metacarpals because the deformity can be more 
easily compensated (Table 42.3).
Metacarpal shaft fractures occur secondary to direct impact or an 
axial loading force. Like metacarpal neck fractures, they also present 
with apex dorsal angulation though they are comparatively less toler-
ant to angulation because more proximal fractures present with greater 
deformity given the same degree of angulation. While angulation is 
easily assessed from x- ray imaging, rotation is assessed more easily 
from physical exam. Malrotation will be noted with overlap of the dig-
its when they are held in flexion (cascade sign) and are often associated 
with oblique or spiral fractures. As little at 10 degrees of malrotation in 
the fifth metacarpal may cause visible deformity. If there are adjacent 
metacarpal fractures, there is high risk for shortening and instability 
A B C
Fig. 42.29 (A) AP and (B) lateral x- rays of proximal phalanx fracture of the fifth finger, resulting in the typical 
angulation from apex volar deforming forces. (C) Illustration of the deforming forces acting on proximal pha-
lanx fractures with the central slip pulling the distal fracture fragment into extension. (Cotterell IH, Richard 
MJ. Metacarpal and phalangeal fractures in athletes. Clin Sports Med. 2015;34:69-98.)
Fig. 42.30 Typical metacarpal fracture apex dorsal angulation occurring secondary to the location of the inter-
osseous muscles. (Khouri JS, Hammert, WC. Hand fractures and joint injuries. Plast Surg. 2018;6:146-169.)
TABLE 42.3 Metacarpal Fracture Allowable 
Angulation
Digit
Acceptable Shaft 
Angulation (Degrees)
Acceptable Neck 
Angulation (Degrees)
II and III 10 10-15
IV 20 35
V 20–30 45a
aVarious sources have quoted acceptable angulation of up to 70 degrees 
for the fifth digit
477CHAPTER 42 Hand Injuries
due to loss of intermetacarpal ligament stabilization. Shortening is not 
well tolerated and may result in pseudoclawing, an extensor lag sec-
ondary to compensatory hyperextension at the MCP leading to inad-
equate extension at the PIP. Greater than 5 mm of shortening in any 
metacarpal is not acceptable because this results in an extensor lag that 
is no longer compensated by the MCP joint’s natural hyperextension 
capability.
Fractures of the metacarpal base occur secondary to an axial loading 
force with the wrist in flexion. These fractures are often intra- articular 
and associated with CMC joint dislocations, which can be missed on 
standard x- ray imaging.
Intra- articular fractures at the base of the fifth metacarpal are also 
known as reverse Bennet fractures. The radial aspect of the fifth meta-
carpal base is stabilized by the intermetacarpal ligament while tension 
from the extensor carpi ulnaris causes ulnar and proximal displace-
ment of the remainder of the base. The hypothenar muscles displace 
the shaft radially.
Differential Diagnosis
In addition to fractures, other injuries around the metacarpal should 
be considered including CMC joint dislocation, clenched fist injury, 
extensor mechanism injury, and FDP or FDS tendon injury. Compart-
ment syndrome should also be considered if there is a crush injury 
mechanism, excessive swelling of the hand, pain out of proportion, or 
neurovascular compromise.
Diagnostic Imaging
Because CMC dislocations with metacarpal base fractures are often 
missed, in addition to standard hand x- rays, a 30- degree pronated 
lateral view for the index and middle fingers should be obtained for 
higher diagnostic sensitivity. Similarly, a supinated lateral view for the 
ring and little fingers should be performed. For metacarpal neck and 
shaft fractures, special attention should be paid to the degree of angu-
lation to determine if reduction is needed (see Table 42.3).
Management
Because of the intra- articular predilection for metacarpal head frac-
tures, patients should be referred to a hand specialist because they will 
likely require open reduction and internal fixation (ORIF). Special 
attention should be paid to the soft tissue surrounding the metacar-
pal head, as puncture wounds, lacerations, and particularly fight bite 
wounds require emergency consultation for surgical débridement 
and irrigation. Patients with closed fractures without signs of open 
soft tissue injury may be splinted in neutral position and referred for 
outpatient hand specialist follow- up within one week. The traditional 
method for splinting metacarpal fractures is in neutral position with 
the wrist at 20 to 30 degrees extension, MCP at 70 to 90 degrees flexion, 
and the PIP and DIP kept in extension.
Non- displaced or minimally angulated fractures of the metacarpal 
neck (below threshold for reduction) can be managed conservatively 
with immobilization for 3 to 4 weeks (see Table 42.2). These inju-
ries that do not exceed the threshold are unlikely to cause functional 
impairment, so do not require anatomical reduction in the ED. The 
traditional recommendation is to immobilize the metacarpal in neutral 
position with a radial (digits 2 and 3) or ulnar gutter splint (digits 4 
and 5). However, recent studies suggest that less immobilization may 
not be harmful and may actually yield benefits. A recent prospective 
study in patients with boxer’s fractures found similar long- term clinical 
and radiologic results in patients treated with functional metacarpal 
splinting (FMS) compared to ulnar gutter splinting, though there was 
actually earlier return of grip strength at 2 months in the FMS group.14 
Similarly, a recent meta- analysis found that immobilization with a 
splint or cast was not superior to soft wrap in most cases.15 Yet, given 
the importance of stability following an acute fracture, we recommend 
standard immobilizationat least as a temporary measure if the patient 
is able to follow up with a hand specialist within one week.
Acute metacarpal neck fractures that exceed the threshold of 
acceptable angulation require reduction. This can be attempted in the 
emergency department via the Jahss manipulation technique for closed 
reduction. Using this method, the MCP joint and PIP joints are flexed 
to 90 degrees, upper (dorsal) pressure is applied through the proximal 
phalanx, and downward pressure is applied over the proximal metacar-
pal shaft (Fig. 42.31).
Metacarpal shaft fractures are managed similarly to metacarpal 
neck fractures, though with less acceptable angulation. The Jahss tech-
nique may be used for closed reduction. Patients with greater than 5 
A B
Fig. 42.31 Reduction of metacarpal fracture using the Jahss maneuver. (A) Arrows indicate direction of pres-
sure for fracture reduction. (B) Fingers are held in intrinsic- plus (safe) position, after reduction, in ulnar gutter 
splint with molding pressure indicated by arrows. (Day CS. Fractures of the metacarpals and phalanges. In: 
Wolfe SW, Hitchkiss RN, Pederson WC, et al., eds. Green’s Operative Hand Surgery. Philadelphia: Elsevier; 
2017:231-277.)
478 PART II Trauma
mm of shortening, clinically significant rotation, and unstable frac-
ture types should have prompt referral to a hand specialist for possible 
ORIF.
Intra- articular fractures at the base generally require surgical fixa-
tion to prevent posttraumatic arthritis.
Thumb Fractures
Clinical Features
Due to the highly mobile nature of the thumb, there is a lower fre-
quency of fractures compared to the other phalanges. Similar to other 
distal phalanges, mallet injuries of the thumb may occur though they 
are rare and occur secondary to avulsion of the extensor pollicis longus 
tendon at its distal insertion point. Mallet injuries of the thumb, unlike 
mallet injuries of the fingers, are less likely to result in subluxation.16 
With a skier’s or gamekeeper’s thumb, there may be an associated avul-
sion fracture at the base of the proximal phalanx.
Most fractures of the thumb metacarpal occur at the base. There are 
strong ligamentous forces limiting abduction of the thumb (anterior 
oblique and first inter- metacarpal ligaments). An axial loading force 
on the partially flexed metacarpal creates an avulsion type fracture. 
The ligamentous forces are so strong that a fracture at the metacarpal 
base is actually far more common than a CMC joint dislocation. Two 
unique fractures at the metacarpal base are the Bennett fracture and 
the Rolando fracture.
The Bennett fracture is an oblique intra- articular fracture accompa-
nied by a dislocation at the metacarpal base (Fig. 42.32A). The anterior 
oblique ligament holds the volar- ulnar base fragment in place while 
the remaining articular surface and shaft are displaced proximally 
and adducted by the abductor pollicis longus and adductor pollicis 
respectively.
The Rolando fracture is a comminuted complete intra- articular 
fracture at the metacarpal base that is T- shaped or Y- shaped on x- ray 
(see Fig. 42.32B).
Differential Diagnoses
When considering fractures of the thumb, other injuries including 
mallet injury, volar plate injury, collateral ligament injury, IP or CMC 
joint dislocation or subluxation, extensor pollicis longus tendon injury, 
or UCL or RCL injury should be considered.
Diagnostic Testing
Special x- ray views are necessary when evaluating potential thumb 
fractures or dislocations because the thumb is situated outside of the 
hand plane. One such view is the Robert view where the hand is hyper- 
pronated with the dorsum of the thumb on the radiograph plate, cre-
ating a true AP view.
Management
There are no major differences in treatment for thumb phalangeal 
fractures compared to digits 2 through 5, though proximal fractures 
should be immobilized with a thumb spica splint for 4 weeks. Due 
to instability and associated deforming forces, both Bennett and 
Rolando fractures require urgent referral to a hand specialist for fur-
ther management.
Joint Injuries
Clinical Features
The interphalangeal and metacarpophalangeal joints of the hand are 
stabilized by multiple tendons and ligaments. In particular, the col-
lateral ligaments protect against radial and ulnar deviation of the IP 
joints. The volar plates are fibro- ligamentous structures that protect the 
joint capsule against hyperextension.
Mechanism predicts the injury. Forced hyperextension of the 
respective joint may result in volar plate tears and dorsal dislocations. 
Lateral forces may result in collateral ligament injury and lateral dislo-
cation. Axial loading forces are responsible for intra- articular fractures. 
Injuries to ligaments generally accompany dislocations and range from 
small tears (grade I) to complete tears (grade III).
Inspection may show deformity and swelling. Active range of 
motion is the best test for joint functioning and stability. Sufficient local 
analgesia (i.e., digital block) is necessary for accuracy of this exam. Pas-
sive range of motion and ligament stressing are useful in identifying 
the location and severity of injuries, though this should be done gently 
to prevent further ligamentous injury.
Differential Diagnoses
The differential diagnoses for joint injuries are extensive and include 
associated fractures, dislocations, subluxations, tendon injuries, and 
ligamentous injuries (see Table 42.2).
A B
Fig. 42.32 Thumb metacarpal intra- articular fractures. (A) AP radiograph demonstrating a Bennett fracture. 
The long arrow points to the fracture site and the short arrow points to the fracture fragment that has minimal 
radial subluxation. Note the minimal subluxation. (B) AP view of a comminuted Rolando fracture. (Scanelli J, 
Deal N, Chhabra B, Sanders T. Hand fractures. In: Miller MD, Sanders TG, eds. Presentation, Imaging and 
Treatment of Common Musculoskeletal Conditions. Philadelphia: Elsevier Saunders; 2012:258-267. Fig 58-7.)
479CHAPTER 42 Hand Injuries
Diagnostic Testing
Standard x- ray imaging should include true lateral films of the affected 
digit to accurately identify dislocations and subtle subluxations. The 
classic “V sign” results from dorsal widening of the joint when there is 
minimal subluxation (Fig. 42.33).
Management
Most dislocations are amenable to closed reduction in the emergency 
department. Reduction should be performed immediately after iden-
tifying the injury because delays are associated with lower success 
rates and higher rates of neurovascular compromise. Following ade-
quate analgesia, gentle longitudinal traction should be applied to the 
affected joint followed by hyperextension (if dislocation is dorsal) or 
hyperflexion (with volar dislocations) along with pressure at the base 
of the dislocated phalanx in the proper direction for realignment (Fig. 
42.34). Active range of motion should be tested following reduction 
and a post- reduction film should be obtained.
Indications for emergent surgical management include neurovas-
cular compromise after closed reduction, inability to reduce (often 
due to obstruction from soft tissue, volar plate, or osteochondral frag-
ments), and contaminated open dislocations requiring extensive irri-
gation. Additionally, dislocations that remain unstable after reduction 
and those accompanied by displaced or sizeable intra- articular frac-
tures require surgical intervention. Surgical referral for open reduction 
is also indicated in chronic dislocations, or those present for greater 
than 3 weeks.
Splinting principles are designed to prevent residual joint and flex-
ion stiffness, which are common complications of immobilization. 
Uninvolved joints should have only minimal immobilization, if any. 
The MCP joint should be immobilized at 60 to 70 degrees flexion, 
whereas the IP joints should be flexed approximately 30 degrees. One 
Fig. 42.33 Typical “V sign” seen on lateral view where there is a frac-
ture at the volarbase of the middle phalanx and dorsal subluxation of 
the PIP joint. (Chauhan A, Sikora- Klak J, Abrams R. Dynamic homemade 
digital external fixators for proximal interphalangeal joint injuries. J Hand 
Surg. 2018;43(9):875. Fig 5.)
Initially
extend
Then flex at the PIP joint
Grasp
dislocated finger
with both hands
Fig. 42.34 Reduction technique for finger dislocation (PIP joint). (Buttaravoli P, Leffler, Stephen M. Minor 
Emergencies, ed 3. Philadelphia: Elsevier Saunders; 2012:419-422. Fig 109-1.)
480 PART II Trauma
exception to this principle is volar dislocations of the PIP which must 
initially be splinted in extension to avoid a boutonnière deformity. Sim-
ple sprains may be treated with buddy taping or dynamic splinting. 
Complete ligament tears require prolonged immobilization and sur-
gical repair.
Interphalangeal Joint Injuries
Clinical Features
The distal interphalangeal joint is highly stable, and dislocations are 
rare. When dislocations do occur, they are almost always dorsal. Radio-
graphs should be analyzed for dislocations complicated with mallet 
avulsion fractures. Uncomplicated dislocations of the DIP are generally 
stable after closed reduction, since the flexor and extensor tendons are 
attached to the distal phalanx.
The PIP joint is the most frequently injured joint in the hand. The 
collateral ligaments and accessory ligaments merge into the volar plate 
which is further anchored by the collateral ligaments proximally (see 
Fig. 42.9). This creates a three- dimensional hinge. Multiple supporting 
structures must be disrupted to cause joint instability. The PIP joint 
may be dislocated in any of three directions—dorsal, volar, or lateral.
Dorsal dislocations of the PIP joint are most common and fre-
quently are associated with ball- handling sports. The mechanism is 
secondary to axial load and forced hyperextension resulting in rupture 
of the volar plate and tearing of collateral ligaments. This creates an 
easily recognizable bayonet- like dorsal displacement deformity seen on 
inspection (Fig. 42.35). Dorsal dislocations accompanied by fractures 
involving greater than one- third of the articular surface are considered 
unstable, because they are associated with greater detachment of the 
collateral ligament insertion at the middle phalanx.
Volar plate tears may also occur secondary to hyperextension and 
may be present without evidence of dislocation at the PIP joint. A volar 
horizontal skin laceration over the joint is often visible along with a 
hyperextension deformity. Pain and locking may be evident on active 
flexion of the PIP joint.
Volar dislocations of the PIP joint are rare and are frequently missed. 
Dislocations occur with disruption of the central slip. The head of the 
proximal phalanx ruptures through the retinacular fibers between the 
lateral band and central tendon (Fig. 42.36).
Lateral dislocations of the PIP joint occur from a lateral force with 
the PIP joint in extension, resulting in rupture of a collateral ligament. 
The patient may present with radial or ulnar deviation at the PIP joint, 
though these dislocations frequently reduce spontaneously. Collateral 
ligament integrity should be tested by providing lateral stress on the 
L
Fig. 42.35 Dorsal dislocation of the PIP joint on radiograph. (Courtesy of 
Timothy Kaufman, MD; Central Michigan University COM)
B CA
Extensor
apparatus
Proximal
phalanx
Middle
phalanx
Volar plate Accessory
ligament
Collateral
ligament
Fig. 42.36 (A) Key stabilizing forces surrounding the PIP joint. (B and C) Examination and radiograph of patient 
with volar PIP dislocation. (Bindra RR, Foster BJ. Management of proximal interphalangeal joint dislocations 
in athletes. Hand Clinics. 2009;25(3):423-435. Fig. 1 and 5.)
481CHAPTER 42 Hand Injuries
radial and ulnar sides of the joint. Ability to flex and extend the finger 
at the PIP joint is usually preserved.
Differential Diagnoses
When suspecting an interphalangeal joint injury, one must also con-
sider associated fractures including open, closed, and avulsion frac-
tures. Tearing of the volar plate, central slip, and collateral ligaments 
commonly accompanies dislocations and subluxations.
Diagnostic Testing
A standard 3- view x- ray of the affected digit is sufficient to identify 
subluxations and dislocations of the IP joints.
Management
Uncomplicated DIP joint dislocations that are functionally stable after 
closed reduction, as tested with active range of motion, should be 
immobilized for 2 to 3 weeks. Immobilization of reduced dislocations 
can be accomplished with an aluminum padded splint extending from 
the dorsal surface of the middle phalanx to the distal phalanx with the 
DIP slightly flexed to 30 degrees.
Closed reduction should be attempted for uncomplicated dorsal 
dislocations of the PIP joint. Functionally stable PIP dislocations and 
those not accompanied by intra- articular fractures can be managed 
with splinting for 2 weeks. Dorsal dislocations are splinted with the PIP 
in slight flexion (30 degrees). Fracture- dislocations of the PIP should 
have hand specialist referral following closed reduction, ideally within 
3 days of presentation.
Patients with suspected isolated volar plate tears at the PIP joint 
should similarly be splinted in 30 degrees of flexion for at least 3 
weeks.17
Reduction of volar dislocations can be challenging given obstruc-
tion from the lateral band. These dislocations often require open reduc-
tion by a hand specialist. We recommend discussing the case with a 
hand specialist prior to attempting closed reduction because many 
advocate for open reduction with central slip repair in all volar dis-
locations. If closed reduction is performed in the emergency depart-
ment, the central slip integrity must be examined afterward. Inability 
to extend the PIP against resistance indicates significant central slip 
injury and the joint must be splinted appropriately in full extension (4 
to 6 weeks) to avoid formation of a boutonnière deformity over time.
Lateral dislocations of the PIP that are deemed stable after reduc-
tion should be splinted with the PIP immobilized at 30 degrees of 
flexion for 2 to 3 weeks, though some advocate for simple buddy or 
dynamic taping. Joints that are unstable or associated with an avulsion 
fracture, require immobilization with prompt surgical referral, ideally 
within 3 days of presentation.
Metacarpophalangeal Joint Injuries
Clinical Features
The metacarpophalangeal joint should be taut in flexion, though it nat-
urally has some laxity in extension allowing some lateral movement. 
Strong collateral ligaments, the transverse metacarpal ligament (volar 
plate), and intrinsic musculature provide significant dynamic stability 
to lateral forces. Thus, injuries to the lateral structures are rare. Injury 
to the collateral ligament should be suspected if there is pain or laxity 
at the MCP joint in extension when radial or ulnar stressing is applied.
In contrast, the shape of the MCP joint and lack of the collateral lig-
aments result in less stability for resisting hyperextension, responsible 
for dorsal dislocations of the MCP joint and hyperextension injuries.
With dorsal dislocations of the MCP joint, there is generally vis-
ible deformity with dorsal displacement of the proximal phalanx, 
hyperextension of the MCP joint, and slight flexion of the interpha-
langeal joints. There are two types of dorsal dislocations: simple and 
complex.
Simple dislocations of the MCP joint are technically subluxations 
because the articular surfaces remain in partial contact. Yet, examina-
tion may show significant deformity with the proximal phalanx locked 
in greater than 60 degrees of hyperextension.
Complex dislocations of the MCP joint occur when the metacar-
pal head ruptures through the volar plate, which becomes entrapped 
within the joint space. Examination may show less hyperextension 
compared to simple dislocations. Classically, there may be dimpling ofthe skin at the proximal palmar crease.
Differential Diagnoses
When assessing injuries at the MCP joint, also consider dislocations, 
subluxations, dorsal lacerations indicating fight bite injuries, associated 
metacarpal head and neck fractures, tears to the volar plate and collat-
eral ligaments, trigger finger, and FDP or FDS tendon injuries.
Diagnostic Testing
Standard 3- view hand x- rays are sufficient in identifying most dislo-
cations and subluxations. However, findings may be subtle for signifi-
cant injuries. For example, complex dislocations of the MCP joint may 
show only mild widening of the joint space, sometimes with presence 
of a sesamoid. Physical examination should be relied upon to assess for 
ligamentous injury; MRI is rarely used for these types of injuries in the 
emergency setting.
Management
Treatment for collateral ligament injury at the MCP is splinting the 
joint in neutral position for 3 weeks. Unstable injuries and those with 
intra- articular fractures require surgical referral.
Simple dislocations of the MCP joint may be treated by closed 
reduction. With the wrist and MCP joint held in flexion, dorsal 
pressure over the proximal phalanx should be applied in a volar 
and distal direction. Special care should be taken to avoid lon-
gitudinal traction on the joint as this may entrap the volar plate 
into the joint, creating a complex dislocation. Following reduc-
tion, the MCP joint should be immobilized at 60 to 70 degrees 
flexion for 1 week followed by buddy or dynamic taping. Complex 
dislocations, due to entrapment of the volar plate, are irreducible 
by closed methods and require emergent surgical consultation for 
open reduction.
Carpometacarpal Joint Injuries
Clinical Features
The carpometacarpal joint is highly stable and requires significant force 
for injury. Dislocations are rare, though are frequently missed. Poste-
rior dislocations (85%) are more common than volar dislocation.18 The 
fifth CMC joint is most frequently involved, often occurring secondary 
to closed fist injury. Dislocations of the fifth CMC (metacarpohamate) 
joint may result in ulnar nerve injury resulting in claw- hand defor-
mity in severe cases. Thorough ulnar nerve testing is required for fifth 
CMC joint dislocations. Examination often reveals no gross deformity, 
though there is usually significant dorsal swelling at the base of the 
metacarpal.
Differential Diagnoses
One should consider associated fractures of the carpal bones and meta-
carpal base, tendon, and ligamentous injuries when assessing injuries 
at the CMC joint.
482 PART II Trauma
Diagnostic Testing
All three radiographs of the hand—PA, lateral, and oblique—should be 
obtained if this injury is a concern. Special attention should be made to 
the lateral and oblique radiographs to identify CMC joint dislocations 
as well as any associated metacarpal fractures which frequently coexist. 
Due to the dorsal positioning of the dislocation, a cursory review of the 
PA film might lead to missing the diagnosis. The lateral film has signif-
icant bony overlap of the heads of the metatarsals so may also conceal 
a fracture or dislocation.
Management
Reduction of CMC joint dislocations should be performed in the emer-
gency department, though hand specialist referral within 24 hours, 
where possible, is recommended because reduction is difficult to main-
tain. Immobilization alone is often inadequate, and surgical interven-
tion is often necessary.
Thumb Dislocations and Ligamentous Injuries
Clinical Features
Interphalangeal joint dislocations of the thumb, similar to DIP joints 
of the other phalanges, are usually dorsal and occur secondary to 
hyperextension injury. The MCP joint of the thumb is the most mobile 
joint in the hand and is oriented obliquely, making it a common site 
of injury from radial forces. Dorsal dislocation may occur from volar 
plate disruption, while lateral dislocation may occur from a collateral 
ligament tear. The mechanism and morphology of the deformity is 
similar to that of other phalanges. Injuries to the collateral ligaments of 
the thumb are common, particularly ulnar collateral ligament injuries 
(ten times more common than radial).19
Ulnar collateral ligament injuries usually occur secondary to sud-
den radial deviation of the thumb while it is abducted. Classically, this 
occurs in skiers falling on an abducted thumb while holding onto a 
pole (skier’s thumb). Less commonly, injuries to the UCL may occur 
chronically from repetitive valgus stress at the MCP joint. Radial collat-
eral ligament injuries occur from sudden ulnar deviation of the thumb 
toward the fingers and palm.
With acute injuries of the collateral ligaments, there is usually pain 
and swelling at the MCP joint of the thumb. In UCL injuries, pain on 
the ulnar side of the thumb with radial stress indicates an injury. The 
classical round palpable mass is rarely noted along the ulnar side of the 
metacarpal neck with a complete tear of the UCL (Stener lesion). Sta-
bility of the MCP joint should be tested in full extension and 30 degrees 
flexion, assessing for UCL and RCL integrity. The examiner should sta-
bilize the metacarpal with one hand and passively stress the proximal 
phalanx in the radial and ulnar direction with the other hand. If there 
is significant laxity at the MCP with radial deviation, assume there is a 
tear to the UCL. Likewise, if there is laxity with ulnar deviation, assume 
there is a tear to the RCL. RCL tears are much less common than UCL 
tears of the thumb. The thumb CMC joint is stabilized anteriorly and 
posteriorly by respective oblique ligaments. Isolated dislocations are 
rare, though associated fractures (e.g., Bennet fractures) are common.
Differential Diagnoses
Associated intra- articular fractures, volar plate, collateral ligament, 
extensor pollicis longus tendon, and abductor pollicis longus injuries 
should be considered.
Diagnostic Testing
X- rays should be performed in patients with suspected UCL or RCL 
injuries, looking for associated subluxation or avulsion fracture. A 
stress view is particularly useful. Greater than 30 degrees of lateral 
laxity compared to the opposite thumb at the MCP joint indicates 
complete disruption of the associated collateral ligament. As with other 
hand injuries, nonemergent MRI has been found to be reliable in iden-
tifying these types of tendinous and ligamentous injuries.20
Management
For IP joint dislocations, closed reduction should be performed fol-
lowed by active range- of- motion testing. Most are stable after reduc-
tion, though integrity of the joint and flexor pollicis longus tendon 
should be examined. The IP joint should be immobilized in 30 degrees 
of flexion for 3 weeks. Irreducible dislocations and open dislocations 
require surgical management.
The same technique for closed reduction of other MCP joints 
should be used for the thumb, avoiding longitudinal traction and like-
wise avoiding entrapment of the volar plate. Stability, particularly of 
the collateral ligaments, should be assessed following reduction. Stable 
dislocations should be immobilized with the MCP joint in slight flex-
ion for 4 to 6 weeks.
For collateral ligament injuries, most stable grade I and II inju-
ries (less than 30 degrees of laxity) may be managed conservatively 
with immobilization of the MCP joint via thumb spica splinting for 
4 weeks. Complete tears (grade III) should likewise be immobilized 
in a thumb spica splint, but also require prompt referral for surgical 
management.
If there is pain and tenderness at the CMC joint of the thumb, lig-
amentous injury or carpal injury should be assumed and thumb spica 
splinting should be performed. Dislocations should be reduced, though 
they are often unstable and require follow- up with a hand specialist.
Tendon Injuries
Lacerations, puncture wounds, forced extension or flexion, and crush 
injuries may result in a tendon injury ranging from strain to complete 
disruption. After a thoroughneurovascular exam and identifying the 
point of maximal tenderness, a digital block should be considered 
prior to assessment of tendon integrity. Each digit should be examined 
individually to avoid a masking effect from adjacent tendons. Motor 
function should be assessed by having the patient flex and extend the 
fingers against resistance. Pain with preserved strength on active range 
of motion may indicate a partial tear, while weakness may indicate 
complete tendon disruption. X- rays should be obtained to assess for 
avulsion fractures which commonly occur with tendon disruptions.
Extensor Tendon Injuries
Clinical Features
The extensor mechanism includes muscles that originate proximal to 
the wrist whose tendons insert on the extensor surface of the fingers 
(extrinsic extensors). The extensor digitorum communis (EDC, dig-
its II–V) connects with the lateral bands to form the central slip. The 
central slip inserts at the base of the middle phalanx and functions to 
extend the phalanx at the PIP joint. The lateral bands themselves arise 
from the intrinsic muscles (lumbricals and interossei) (see Fig. 42.9).
The extensor mechanism is divided into 9 zones. The classification 
is relevant to specific injuries and management of those injuries. The 
even numbered zones are located over bones while the odd numbered 
zones are located over joints. Zone VIII and IX are located proximal to 
the wrist (Fig. 42.37). The thumb has its own classification: TI for the 
interphalangeal joint, TII for the proximal phalanx, TIII for the MCP 
joint, TIV for the metacarpal, and TV for the carpus.
Thorough inspection should focus on evidence of lacerations, open 
wounds, and swelling. The extensor tendons should be palpated for 
tenderness, laxity, or step- off. This is best accomplished with the palm 
483CHAPTER 42 Hand Injuries
down on a table. The most common extensor tendon injury is mallet 
finger in zone I.
Zone I Extensor Injuries. This zone includes the distal phalanx and 
DIP joint. Terminal tendon disruption from sudden flexion of the 
extended DIP joint results in the common mallet injury (Fig. 42.38). 
This injury is common in ball- handling sports from a jammed finger. 
There is often pain and tenderness over the DIP joint, and extensor lag 
is associated with complete disruptions. X- rays should be evaluated for 
associated avulsion fractures, common with this injury.
Zone II Extensor Injuries. Injuries occur over the middle phalanx 
and are usually due to a laceration. Rarely, a mallet deformity will form 
from a laceration of the tendon’s central and lateral bands.
Zone III Extensor Injuries. Injuries in this zone involve the PIP joint 
and the central slip. Boutonnière injury (flexion at the PIP joint with 
hyperextension at the DIP and MCP joints) occurs with central slip 
disruption (Fig. 42.39). Multiple mechanisms are responsible for these 
injuries including forced PIP flexion, deep laceration, blunt injury to 
the dorsum of the PIP joint, or volar PIP joint dislocation.
If there is disruption of the central slip and triangular ligament, 
there will be inability to extend the finger at the PIP joint. However, 
if the triangular ligament remains intact, there may be normal motion 
initially. Because deformities may not form until after the acute phase 
of injury, there should be a high index of suspicion and a low threshold 
for splinting.
Integrity of the central slip is best assessed with the Elson test. For 
this test, the PIP is held in maximum passive flexion. The examiner 
holds resistance against extension at the middle phalanx. If the central 
slip is intact, when attempted, the patient will not be able to extend 
the distal phalanx at the DIP due to distal slack at the lateral bands. 
Conversely, if there is a complete disruption of the central slip, there is 
increased tone at the DIP joint and there is extension or hyperexten-
sion at the PIP joint, indicating a positive test (Fig. 42.40).
The modified Elson test offers direct comparison of the injured to 
uninjured digit. The patient is asked to hold fingers against each other 
at the dorsal surface of the middle phalanx with the PIP joint at 90 
degrees. The patient then attempts to extend each finger. If there is sig-
nificant difference in the ability to extend the DIP in one digit com-
pared to the digit in the other hand, assume a central slip injury (see 
Fig. 42.40).
The examiner should be aware of the pseudo- boutonnière deformity 
where PIP flexion contracture is present though there is no increased 
I
II
III
IV
V
VI
VII
VIII
IT
IIT
IIIT
IVT
VT
Fig. 42.37 Extensor tendon injury zones of the hand. Zones VIII and 
IX are located proximal to the wrist. (Rosenthal EA, Elhassan BT. The 
extensor tendons: evaluation and surgical management. In: Skirven TM, 
Osterman AL, Fedorczyk JM, Amadio PC. Rehabilitation of the Hand 
and Upper Extremity, ed 6. Philadelphia: Elsevier Mosby; 2011:487-520. 
Fig. 38-10.)
Fig. 42.38 Mallet finger deformity seen clinically with extensor lag and radiographically with an associated 
avulsion fracture. (Zhang W, Zhang X, Zhao G, Gao S, Yu Z. Pressing fixation of mallet finger fractures with 
the end of a K- wire. Injury. 2016;47(2):377-382. Fig. 3 and 7.)
484 PART II Trauma
extensor tone at the DIP (negative Elson test). Thus, the extensor 
mechanism is actually intact for patients with this deformity.
Zone IV Extensor Injuries. This zone includes injuries over the 
proximal phalanx. Like in zone II, injuries usually occur from 
lacerations. The tendon is wide and flat at this location, so most 
lacerations are partial.
Zone V Extensor Injuries. Injuries at this zone involve the sagittal 
band at the MCP joint. The most common injury is to the radial sagittal 
band of the middle finger. The common mechanism is forced flexion or 
direct blunt force. Swelling and tenderness over the dorsal MCP joint 
will generally be appreciated on exam. The patient can usually keep 
the joint in extension, though with active extension from the finger 
in flexion, there is a snapping relocation of the extensor mechanism. 
Human bite wounds should be considered with any laceration in this 
area (i.e., fight bite).
Injuries in zone V are classified based on whether there is no tendon 
instability (type I), tendon subluxation or snapping (type II), or com-
plete tendon disruption (type III). One specific type of injury is boxer’s 
knuckle. As the name implies, this injury usually occurs from punch-
ing an object, resulting in rupture of the sagittal band at the MCP joint.
Zone VI Extensor Injuries. Injuries at this zone occur over the 
metacarpals, most frequently secondary to lacerations. Complete 
lacerations are often missed as full extension may remain intact due 
to juncturae tendinum transmitting extension forces from adjacent 
tendons.
Zone VII Extensor Injuries. Lacerations over the carpals and extensor 
retinaculum account for most injuries at this zone, though injuries 
may also occur with a closed fracture. Wounds should be explored for 
tendon injury while the patient flexes and extends the fingers.
Differential Diagnoses
Patients with suspected extensor tendon injury often have associated 
avulsion fractures at the insertion points of the extensor mechanism 
(e.g., mallet finger). Patients with zone V extensor tendon injuries have 
a snapping relocation of the extensor mechanism with active extension, 
which is often mistaken for a trigger finger. With pain and swelling 
near joint spaces, there may be underlying ligamentous injury, fracture, 
dislocation, or subluxation. As there is difficulty extending the digit, 
one should also consider flexor tenosynovitis or Dupuytren contrac-
ture. To help with the differential diagnosis, note that Dupuytren con-
tracture is a chronic condition and does not present as an acute injury.
Diagnostic Testing
Due to the strength of the tendon attachments to the bones of the 
hand, x- ray imaging should be done for symptomaticpatients. In 
the ED, more advanced imaging is not generally used, though the 
Extensor
Flexor
Boutonnière
PIP axis
ORL
Extensor
Flexor PIP axis
Swan neck
ORL
A
B
C
D
Fig. 42.39 (A) A Boutonnière injury (zone III injury) allows the ORL to subluxate volar to the axis of rotation 
at the PIP joint. (B) Mallet finger (zone I injury) that has resulted in a swan- neck deformity due to dorsal sub-
luxation of the oblique retinacular ligament (ORL) (lateral bands). (C) Boutonnière deformity seen on physical 
examination. (D) Swan- neck deformity seen on physical examination. (A and B: Bortel DT. Extensor tendon 
repair. In: Pfenninger JL, Fowler GC. Pfenninger and Fowler’s Procedures for Primary Care, ed 3. Saunders; 
2020:1154-1159. Fig. 172.1; C: Courtesy of Anthony Zacharek, MD; D: Courtesy of Mary Jo Wagner, MD, 
FACEP and Thomas Ferreri, MD.)
485CHAPTER 42 Hand Injuries
utility of ultrasound for making the diagnosis of tendon injury is being 
investigated.21-23
Management
Closed extensor injuries are treated acutely with immobilization. 
Grossly contaminated open lacerations, including crush injuries and 
large open wounds, should have emergent consultation with a hand 
specialist for operative management. Irrigation, tetanus immunization, 
and IV prophylactic antibiotics covering skin flora (e.g., first- generation 
cephalosporin such as cefazolin 1 g IV q8 hours or for patients with 
penicillin allergy, vancomycin 1 gm IV with subsequent dosing calcu-
lated by pharmacy) should be initiated in the emergency department. 
Simple, noncontaminated extensor tendon lacerations may be repaired 
by the EM physician if properly trained with this procedure (see details 
later). Patients with open lacerations should have thorough irrigation 
and splinting. They should be discharged with prophylactic oral anti-
biotics covering skin flora (e.g., a first- generation cephalosporin such 
as cephalexin 500 mg q8 hours for 7 to 10 days or for penicillin allergic 
patients, doxycycline 100 mg po BID for 7 to 10 days).
Zone I Extensor Injuries Management. Most mallet finger 
injuries are successfully treated with immobilization, though injuries 
accompanied by fracture dislocations may require surgical fixation. 
For splinting, only the DIP joint should be immobilized, and it should 
be held in full extension for 6 to 8 weeks followed by nighttime only 
splinting. A premolded Stack splint is often placed due to its ease of 
use while performing normal activities. If this is not available, use of an 
AlumaFoam splint on the dorsal side of the finger is also appropriate. 
Some patients (15%) have residual extensor lag following splinting, 
which is considered an acceptable result.24 We recommend hand 
specialist follow- up within one week of injury.
Patients with improperly treated mallet injuries may develop a 
swan- neck deformity where there is hyperflexion at the DIP joint with 
hyperextension at the PIP joint (see Fig. 42.39). Duck bill deformity 
may develop at the thumb.
Zone II Extensor Injuries Management. Incomplete lacerations can 
be managed with simple closure and splinting of the DIP in extension 
for 2 weeks. Complete lacerations require urgent surgical follow- up for 
repair and the splint will need to be maintained for 6 weeks. Similar 
to zone I injuries, if untreated, the patient may develop a swan- neck 
deformity.
Zone III Extensor Injuries Management. Central slip disruptions 
(boutonnière injuries) are treated by splinting the PIP joint in extension 
for 4 to 6 weeks followed by night splinting. DIP flexion exercises 
should also be performed multiple times each day to help correctly 
align the lateral bands.
Chronic boutonnière injuries should similarly be treated conserva-
tively with splinting, though these patients often require surgical PIP 
joint release and should be referred to a hand specialist. Depending 
on the degree of flexor tendon contracture, complete extension may be 
unrealistic with initial splinting. Serial splinting, until complete exten-
sion is obtained, may be necessary.
Zone IV Extensor Injuries Management
If there is no loss of extension, conservative treatment with splinting 
is usually sufficient. Splinting, like for zone III injuries, should be per-
formed with the PIP in extension and the DIP free to move. Tendon 
repair is indicated in patients with loss of active extension.
Zone V Extensor Injuries Management. Stable sagittal band injuries 
(type I) can be treated with buddy or dynamic taping for 3 to 4 weeks. 
Acute injuries with subluxation (type II) may be treated with an MCP 
A
B C
Fig. 42.40 The Elson test (A and B) and modified Elson test (C) are used for evaluation of central slip extensor 
injury. (A) With a disrupted central slip, the distal phalanx is held in extension as attempted active extension 
of the PIP joint against resistance allows proximal movement of the origin of the lateral bands. (B) With an 
intact central slip, attempted active extension of the PIP joint against resistance affects the middle phalanx 
but prevents extension of the distal phalanx. (C) Abnormal DIP extension of the injured left middle finger as 
demonstrated by modified Elson test. (A and B: From: Gause T. Boutonniere deformity. In: Miller MD, Hart JA, 
MacKnight JM. Essential Orthopaedics, ed 2. Philadelphia: Elsevier; 2020:327-329. Fig 84.3; C: Posner MA, 
Green SM. Diagnosis and treatment of finger deformities following injuries to the extensor tendon mecha-
nism. Hand Clinics. 2013;29(2):269-281. Fig 13.)
486 PART II Trauma
flexion blocking splint (MCP joint in extension with the PIP and DIP 
joints free) for 8 weeks. Complete disruptions of the sagittal band (type 
III) should also be stabilized with an MCP flexion blocking splint, 
though patients with these injuries require referral to a hand specialist 
for surgical repair. Similarly, patients who have failed splinting and 
those with chronic injuries (>3 weeks) require hand specialist follow- up 
for surgical management.
Zone VI Extensor Injuries Management. Clean, complete 
tendon lacerations may be repaired by an EM physician, though we 
recommend discussion with a hand specialist first, if possible. Urgent 
follow- up with a hand specialist is indicated, ideally within one week. 
Initial splinting should immobilize the wrist at 30 degrees of extension, 
MCP joint in extension, and the PIP and DIP joints free to move.
Zone VII Extensor Injuries Management. If there is no need for 
immediate surgical intervention (such as gross contamination), 
wounds should be thoroughly irrigated followed by skin closure. The 
hand and wrist should be immobilized with a volar splint, keeping the 
wrist at 30 degrees of extension and the MCP joints at 15 to 20 degrees 
of flexion. Hand specialist follow- up is indicated, ideally within one 
week.
Disposition
In any case where there is concern for an extensor tendon injury, either 
open or closed, referral to a hand specialist is recommended from the 
ED. Due to risk of chronic functional impairment, patients with com-
plete tendon lacerations should have urgent follow- up with a hand spe-
cialist so that surgery may occur within 2 to 3 weeks. Any delay that 
might come about by an initial referral to a primary care appointment 
should be avoided if possible, and patients should be instructed about 
this timeline. Loss of motion is the most common chronic complica-
tion of tendon injuries. This may be accompanied by extensor lag or 
joint contracture.
Flexor Tendon Injuries
Clinical Features
The majority of flexor tendon injuries are open injuries secondary to a 
deep laceration.
Closed flexor tendon injuries are less common in general and are 
less common than extensor tendon injuries. They tend to occur in ath-
letes from having forced hyperextension of a digit that is in active flex-
ion. The two most common flexor tendon injuries of the hand involve 
the flexor digitorum profundus (FDP) and the flexor digitorum super-
ficialis (FDS) (Fig.42.41). Most closed flexor tendon injuries occur 
at the fourth finger, involving the FDP. The FDS is generally spared. 
Patients will complain of a “pop” or “tear” with pain over the flexor 
surface, as well as loss of active flexion or weakness of the tendon. Bow- 
stringing tends to occur only when multiple pulleys have been injured. 
This usually involves the two strongest pulleys A2 and A4 (see Fig. 
42.12). A flexor tendon injury should be considered when an injured 
finger does not assume its naturally flexed position on cascade testing.
Specific tendon function testing should be performed (see Table 
42.1). Recall that the FDP tendon inserts at the base of the distal pha-
lanx and the FDS tendons insert at the base of the middle phalanx. The 
FDP tendon should be examined by holding the patient’s MCP and PIP 
joints in extension and having him or her attempt to flex the DIP joint. 
The examiner should be sure not to impede the motion of the other 
digits when doing this or a false- positive test can occur. Inability to 
flex indicates a tendon laceration. Weakness or pain when flexing indi-
cates that there is likely incomplete disruption or strain. To accurately 
assess FDS integrity, the FDP must be restrained. This is accomplished 
by holding all uninjured digits in full extension. Inability to flex at the 
PIP using this technique indicates FDS disruption. If there is partial or 
complete disruption of the FDS, the involved finger will rest with less 
flexion than normal and will be unable to flex at the PIP joint. With 
similar injury to the FDP, the PIP joint will be held in extension and 
the patient will be unable to flex at DIP joint or be able to pinch or grip 
with this finger.
Tendon avulsions are very rare in isolation for FDS injuries, though 
are far more common with the FDP tendons. There are three main 
types of FDP avulsion injuries. Type I involves a completely avulsed 
tendon migrating proximally through the flexor sheath into the palm. 
There is risk for compromised vascular supply to the tendon and sur-
gery is recommended as soon as possible (no later than 7 to 10 days). 
Type II injuries involve a complete avulsion with proximal retraction to 
the level of the PIP joint. Similar to type I injuries, the patient may have 
Flexor digitorum profundus
Vincula longa
Digital fibrous sheath
Vincula brevia
Radial artery
First dorsal interosseous
1st lumbrical
Flexor digitorum superficialis
Dorsal extensor expansion
Extensor pollicis brevis
Extensor pollicis longus
Abductor pollicis brevis
Oblique part of
adductor pollicis
Transverse part of
adductor pollicis
Fig. 42.41 Lateral view of the hand showing the flexor tendons of the finger. (From Standring S: Gray’s Anat-
omy: The Anatomical Basis of Clinical Practice, ed 39. Edinburgh: Churchill Livingstone; 2005.)
487CHAPTER 42 Hand Injuries
compromised vascular supply and patient should have expedited surgi-
cal repair. For type III injuries, the avulsed tendon retracts only to the 
level of the A4 pulley. There is less concern for vascular compromise, 
though surgery is still recommended within 7 to 10 days.
The flexor tendons are divided into 5 anatomic zones (Fig, 42.42). 
Zone I extends from the insertion of the FDP at the distal phalanx to 
just distal to the insertion point of the FDS at the middle phalanx. FDP 
tendon avulsion from its insertion at the base of the distal phalanx is 
the most common (jersey finger) injury. With this specific injury, the 
patient is unable to flex the DIP. It classically occurs in football players 
who may grab onto an opponent’s jersey to tackle or slow the runner 
and there is forced hyperextension with the digit in active flexion.
Zone II extends from the distal palmar crease to the proximal por-
tion of the middle phalanx and includes both FDP and FDS tendons. 
Because the injured tendons and associated structures are within the 
tight space of the flexor sheath in this zone, repair is technically more 
demanding and results in a greater frequency of complications relative 
to other zones. As a result, it has been historically referred to as “no 
man’s land.” Advances in technique over the years have made primary 
repair of flexor tendons a standard option for treatment.
Zone III extends from immediately distal to the carpal tunnel to 
the proximal flexor sheath of the digits. Generally, injuries to this zone 
have good outcomes.
Zone IV includes the carpal tunnel. Damage to the median nerve is 
common, stressing the importance of a thorough neurovascular exam. 
Because of protection from the flexor retinaculum, other injuries in 
this zone are relatively rare.
Zone V is proximal to the carpal tunnel. Injuries in this zone usually 
occur from a deep laceration and involve multiple tendons.
Differential Diagnoses
Associated avulsion fractures are common with flexor tendon injuries 
(e.g., jersey finger). Other underlying fractures, ligamentous injuries, 
dislocations, and subluxations should also be considered.
Diagnostic Studies
X- rays may be obtained to rule out associated avulsion fractures. Ultra-
sound has also become increasingly popular as a dynamic bedside 
study.21-23
Management
Patients with flexor tendon injuries, both open and closed, should see 
a hand specialist given risk for chronic disability. Urgency depends on 
the injury, and any acute rupture or laceration is urgent. Emergency 
consultation is indicated in patients with associated open fractures or 
dislocations, grossly contaminated wounds, bites, arterial injury, or if 
the wound overlying the tendon cannot be closed in the ED. Follow- up 
within 3 days is indicated for most other patients with acute flexor ten-
don lacerations, because delay may result in retraction of the tendon 
ends, creating a more difficult repair and risk for worse outcome.
The tendon should also be immobilized with a blocking splint to 
prevent further retraction of the flexor tendons. Splinting should be 
performed with the wrist in neutral to slightly flexed position, the MCP 
joints flexed to 70 to 90 degrees, and the IP joints minimally flexed 
at 10 to 15 degrees. A thumb spica splint should be used for patients 
who have flexor tendon lacerations involving the thumb with the wrist, 
MCP, and IP joints in similar flexion.
Patients with any open wounds should be started on oral antibiotics 
covering skin flora for 5 to 7 days. Cephalexin 500 mg PO TID for 7 to 
10 days or doxycycline 100 mg PO BID for 7 to 10 days (for penicillin- 
allergic patients) are appropriate regimens.
Disposition
Primary repair, or end- to- end repair, is defined as occurring within 
24 hours of injury.25 Referral for delayed repair, defined as occurring 
within 3 weeks of injury, may be considered if an experienced specialist 
is not available on the day of the injury and the wound has not been 
grossly contaminated. Direct communication with the hand specialist 
should occur to help ensure there is timely follow- up, since the success 
Superficialis insert
Proximal A3
Distal A2
Proximal A1
Transverse 
carpal ligament
Carpal tunnel
Distal
Zones
I
II
III
IV
V
Middle
Proximal
Fig. 42.42 Flexor tendon zones. (From: Chang J, Legrand A, Valero- Cuevas F. Anatomy and biomechanics of 
the hand. In: Plastic Surgery: Vol 6: Hand and Upper Extremity, ed 4. London: Elsevier; 2017:1-48. Fig. 1.39.)
488 PART II Trauma
and ease of the repair is improved with less delay than 3 weeks. If the 
patient will be undergoing delayed primary closure, the overlying 
wound should be thoroughly irrigated and closed with loose sutures 
and the hand splinted in the functional position.
Adhesions, infection, and tendon contracture are common compli-
cations. One rare complication following repair is recurrent rupture. 
This usually occurs within 5 weeks of repair. Patients will present to the 
ED complaining of feeling a “pop” or new acute pain with a sudden loss 
of function if the patient is in a dynamic splint. The diagnosis can oftenbe made by noting an abnormal flexion cascade sign. The EM physician 
should avoid having the patient attempt any flexion activities that have 
not already been approved by the hand specialist or physical therapist 
and should not remove the splint. Referral back to the hand specialist 
within 3 days is appropriate.
Trigger Finger
Clinical Features
Trigger finger, often referred to as stenosing tenosynovitis, occurs from 
overuse. The common mechanism is repetitive forceful flexion. This 
leads to inflammation and narrowing at the A1 pulley, thereby inhib-
iting normal smooth tendon movement. The patient will usually com-
plain of catching and pain with flexion and extension of the fingers 
(Fig. 42.43). Trigger finger is most common in patients with underlying 
inflammatory joint disease, diabetes mellitus (DM), and hypothyroid-
ism. A snapping sensation is appreciated with examination of active 
and passive range of motion. In chronic cases, a nodule may be felt on 
the flexor surface of the MCP joint.
Differential Diagnoses
When considering trigger finger, one should consider underlying 
inflammatory joint disease, subluxation of the extensor tendon, or 
Dupuytren contracture. In the presence of preceding trauma, one 
should also consider underlying fracture, tendon injury, or ligamen-
tous injury.
Diagnostic Testing
The diagnosis of trigger finger is made exclusively from history and 
exam, but if there is more to the clinical picture and there is concern 
for an underlying pathology such as DM, hypothyroidism, or inflam-
matory joint disease, then laboratory studies including blood glucose, 
HgbA1c, TSH, free T4, ESR, and CRP may be obtained in the ED. Hand 
radiographs are generally not needed, but if there is a history of acute 
trauma or concern for an avulsion injury, x- rays may be performed to 
rule out an underlying fracture.
Management
Initial treatment of trigger finger involves conservative measures 
including NSAIDs and splinting. Immobilization with an MCP block-
ing splint at slight flexion (10 to 15 degrees) for 6 to 10 weeks has 
been shown to improve symptoms.26 Corticosteroid injections have 
also been shown to be effective in reducing symptoms though there is 
higher risk for recurrence (50% at 1 year). Injections may be performed 
by the EM physician, though we also recommend that injections be 
reserved for patients who have failed conservative measures. Following 
acute treatment, the patient should modify activity to limit overuse and 
recurrence.
Hand specialist referral for surgical management (A1 pulley release) 
is indicated in patients who fail conservative treatment. A Cochrane 
review of two RCTs comparing treatment with open surgery versus 
steroid injection (control) found that 92% of patients had resolution 
of symptoms without recurrence compared to 61% of patients in the 
control group. There is a lower risk of recurrence in patients with open 
surgery, though there are greater complaints of pain during the first 
week following treatment.27
Corticosteroid injections may be used in patients with trigger fin-
ger who have failed conservative measures such as splinting, icing, 
and NSAIDs. Corticosteroid injections have been shown to improve 
long- term pain in patients with trigger finger. In one study, greater 
than 68% of patients reported complete resolution in pain and snap-
ping one month after the injection. In this same study, greater than 
57% reported resolution of PIP flexion contracture.28 There are two 
methods for corticosteroid injections in these patients: intra- sheath 
injection and extra- sheath injection. Ultrasound guidance is helpful 
in identifying landmarks. A linear- array transducer should be placed 
in the long- axis orientation along the volar side of the affected finger 
at the MCP joint.29 The flexor digitorum superficialis and flexor dig-
itorum profundus tendons as well as the A1 pulley should be identi-
fied (Fig. 42.44). For the intra- sheath technique, at approximately 45 
degrees and using a distal to proximal long- axis approach, the needle 
should be advanced until the tip of the needle is between the FDS and 
FDP tendons. Approximately 0.5 mL of steroid such as triamcinolone 
acetonide 10 mg/mL suspension, mixed with a local anesthetic, is 
injected. The extra- sheath technique is similar, though the tip of the 
needle should rest at the distal end of the A1 pulley, superficial to the 
FDS and FDP, which is the site of injection. If there is resistance with 
injection or if the needle moves with flexion and extension of the digit, 
the needle is likely deep in the tendon and it should be withdrawn 
slightly. If, with flexion and extension of the digit, there is a sensa-
tion of the tendon rubbing against the needle point but no significant 
movement of the needle, it is likely in correct position in the tendon 
sheath.
Finger and Nail Bed Injuries
Nail Bed Injuries
Clinical Features. The nail bed is frequently injured in a manner 
that ranges from minimal to severe. Injury occurs after direct 
trauma to the fingertip with the nail compressed against the thin 
layer of skin (nail bed) and the bony tuft immediately underneath. 
A subungual hematoma or bleeding under the nail plate is described 
by the percentage of the nail bed that is covered by the blood with an 
unbroken fingernail and intact nail root. Pain results from the pressure 
caused by the blood within the closed space of the nail plate, nail bed, 
and nail fold. Identification of the extent and depth of any laceration of 
Fig. 42.43 Trigger finger in a patient with the ring finger stuck in flexion. 
(Courtesy of Anthony Zacharek, MD)
489CHAPTER 42 Hand Injuries
the nail bed or along the lateral or proximal nail folds will determine 
management options.
Differential Diagnoses. When evaluating a patient with a suspected 
nail bed injury, the EM clinician should also consider an underlying 
tuft fracture, open fracture, subungual hematoma, mallet injury, or 
FDP tendon injury.
Diagnostic Testing. Imaging is needed to determine if there is 
fracture of the finger tuft. PA, lateral, and oblique radiographs will 
identify a fracture and determine if surgical repair will be needed. 
Comminuted fractures are generally stable due to the fibrous septae of 
the pulp that are tightly adherent to the tuft. Transverse fractures of the 
distal phalanx and intra- articular fractures will need surgical referral, 
ideally within one week. If the only injury is a subungual hematoma, 
an x- ray is not needed if the mechanism or clinical findings do not 
indicate a fracture that would leave an unstable fingertip.
Management. For a subungual hematoma covering greater than 
50% of the nail bed, the typical practice is to trephinate, or create an 
opening in the nail to release the blood. A hole to provide drainage 
of the hematoma can be created with a sterile 18- gauge needle or 
electrocautery. Several studies have shown that if the nail remains 
generally intact, trephination without nail bed repair achieves equal 
healing and cosmesis compared to the more invasive and painful 
removal of the nail and repairing the nail bed. If the fracture is only 
a parcellar (nondisplaced) fracture of the fingertip, no treatment with 
antibiotics is needed (Fig. 42.45).
If a finger tuft is unstable due to a fracture, surgical repair is needed 
to stabilize the bony support and use of the finger. Repair of the tissue 
injuries can be done during the surgical procedure, though some EM 
clinicians will primarily repair the laceration, as the bony damage can 
be stabilized at a later time. The decision whether or not to primarily 
repair the laceration in this situation is dependent on the local standard 
of care.
If there is disruption of the nail bed or root, then repair of these 
structures should be done (Fig. 42.46). Anesthesia using digital block 
in older children and adults is appropriate, though younger children 
may need procedural sedation to accomplish the repair. Use6-0 
absorbable suture to directly repair the laceration, or tension sutures to 
approximate the nail bed when the tissue is too disrupted. The goal is to 
cover the bony surface as well as possible. Some practitioners have used 
tissue adhesive to repair the nail bed, which may be appropriate instead 
of suturing if approximation is more easily achievable. Some practi-
tioners use the tissue adhesive to repair the nail plate if it is cracked, so 
it can be used to cover the nail bed. Subsequent dressing with a nonad-
hesive covering is needed.30
Specific recommendations regarding the replacement of the nail 
plate after nail bed repair are rapidly changing. Historically, the practice 
has been to replace the nail plate after repairing nail bed lacerations, 
including putting the nail plate into the nail fold to prevent blocking 
the ability of a new nail to grow from the germinal matrix. However, 
no systematic trials have been done to determine if this is necessary or 
might decrease the infection rate (2% to 5%). In a recent large British 
study, one- third of specialists did not replace the nail plate and of those 
who did replace the nail plate, one- third did not secure the nail and 
20% used tissue adhesive.31 A more recent pilot study showed fewer 
infectious complications and less pain without replacement of the nail. 
A large prospective randomized trial is in progress to delineate a more 
definitive recommendation.32,33 With the current debate in the litera-
ture, we recommend repositioning the nail after repair of the nail bed. 
The nail serves as the best source of a biologic splint for the injuries of 
the soft tissues and bone. If the nail is reinserted under the eponychial 
fold, the soft tissue can often be stabilized to it.
Most studies of antibiotic use in nail bed injuries with disruption 
of the nail plate included only patients that were referred to hand spe-
cialists, providing a selected population; no ED- based studies demon-
strating appropriate treatment were found. In the survey of current 
practice for consultants caring for pediatric hand injuries in Britain, 
half of nail bed injuries were generally associated with fractures of the 
distal phalanx. Almost two- thirds used antibiotics even if there was no 
underlying fracture associated with a nail bed injury.31 As previously 
noted, distal phalanx fractures have less periosteal stripping, so they 
do not have the infection rate of other open fractures in the body. A 
2016 meta- analysis suggests that the focus of treatment should be on 
prompt irrigation and early débridement without the need for pro-
phylactic antibiotics. Specifically speaking to fingertip entrapment (an 
injury generally from a finger being crushed in a door or window), 
the most recent Cochrane review indicates there are no well- designed 
studies to guide our practice for any specific repair or the need for 
antibiotics. Internationally, the practice variability ranges from giving 
Metacarpal
head
Metacarpal
head
Proximal
phalanx
Proximal
phalanxA B
Fig. 42.44 Intra- sheath steroid injection technique using ultrasound guidance. (A) The needle tip is placed 
between the FDS and FDP tendons (arrow). (B) Expansion of material into the space between the FDS and 
FDP tendons or the margin of the flexor tendons (arrowheads). (Reprinted by permission of Elsevier, from 
Shinomiya R, Sunagawa T, Nakashima Y, Yoshizuka M, Adachi N. Impact of corticosteroid injection site on the 
treatment success rate of trigger finger: a prospective study comparing ultrasound- guided true intra- sheath 
and true extra- sheath injections. Ultrasound Med Biol. 2016;42(9):2203-2208.)
490 PART II Trauma
a first dose of IV first- generation cephalosporin followed by 10 days of 
oral cephalosporin, to no antibiotics except for clearly contaminated 
wounds. Without clear evidence, following the recommendations of 
the local hand specialist that will ultimately care for the patient is most 
appropriate.
Disposition. The injuries resulting in subungual hematomas with 
non- displaced fractures can be followed up by primary care physicians 
as most do not need further treatment. Hand specialists should be 
consulted if primary care follow- up is not an option, and for injuries 
that are complex, including those with missing tissue, unstable 
fractures such as transverse fractures of the distal tuft or fractures that 
involve a joint.
Amputations
Fingertip Amputations
Clinical Features. Amputations of the fingertips are common, most 
often occurring in children. These injuries can result in macerated tissue, 
but any available amputated part should be initially preserved. With 
amputations of the fingertip, there are several different classification 
systems, based on the involved vascular structures or tissue structures. 
For EM physicians, the injuries have been classified by zones as shown 
in Figure 42.47. Zone I is distal to the bony distal phalanx, zone II is the 
area between the distal phalanx and the lunula, and zone III is proximal 
to the lunula. Practically, a functional description is more helpful to the 
hand specialist. The injuries in zone I and II allow for retention of the 
full function of the digit, even if there is some shortening of the digit. An 
injury more proximal than the lunula line generally indicates damage 
or loss of the flexor digitorum profunda (FDP) with the resultant loss 
of flexion and stiffness at both the DIP and PIP joints. The presence or 
absence of exposed bone will also determine management. In young 
children (less than 3 to 4 years old) with distal tip amputations, the 
tissue can be reattached as a composite graft if it measures typically 1.0 
cm in size or less. Consultation with a hand surgeon is recommended 
in these situations.
With more proximal amputations, an accurate description or image 
of the injury will assist in the determination of where and which man-
agement would be appropriate. The hand specialist can help the EM 
physician determine if reimplantation is the proper course of action. 
Indications for reimplantation include amputation of the thumb, mul-
tiple adjacent digits, pediatric patients, and clean, sharp amputations. 
Relative contraindications include severely crushed or contaminated 
wounds, patients with significant comorbid conditions, and multilevel 
amputations of the same digit.
Differential Diagnoses. When caring for a patient with a digit 
amputation, one should consider associated foreign bodies, proximal 
fractures, ligamentous injuries, tendon injuries, and neurovascular 
injuries.
Diagnostic Testing. Standard 3- view x- rays of the affected digit 
should be performed.
Management. Initial management includes assessment of the 
wound, control of bleeding, and thorough irrigation of the injury 
without further disruption of the tissue. A methodical exploration 
of the injury to provide a detailed description to the hand specialist 
will allow for determination of the appropriate management. One of 
the most important objectives is to identify if there is disruption of 
the proximal portion of extensor or flexor tendon attachment to the 
distal phalanx. The work- up is assisted by appropriate radiographs, 
identifying any chip fractures. Coordination and possible transfer 
to a center with hand specialists that perform microsurgery may be 
needed. If reimplantation of finger or fingertip is to be attempted, the 
Fig. 42.45 Subungual hematoma in a 6- year- old boy with middle and ring fingertip crush injury. (Nellans, KW, 
Chung KC. Pediatric hand fractures. Hand Clini. 2013;29(4):569-578.)
491CHAPTER 42 Hand Injuries
amputated tissue should be placed in a normal saline- soaked gauze, in 
a clean plastic bag, and then this bag is placed in ice water to promote 
its viability over the next few hours.
In patients with small tuft avulsions (defined as less than 1 cm3 
loss of soft tissue with the nail intact and covered bone), healing by 
secondary intention is appropriate and doesnot seem to prolong 
pain or increase infection. The wound should be thoroughly irrigated 
and débrided of nonviable tissue, then loosely approximated if tissue 
allows. Patients generally report moderate discomfort for 7 to 10 days, 
with complete healing in 4 to 6 weeks, so appropriate counseling to set 
reasonable expectations should be provided to patients.34 Even with a 
small tip of bony exposure, using a rongeur to trim the bone back and 
allowing it to heal with secondary intention has not been shown to 
change long- term outcome compared to other surgical options (Fig. 
42.48). If coverage is needed for the tuft, then soft tissue from the pulp 
can be obtained with local tissue rearrangement or for a flap closure, 
such as a V- Y advancement flap (Fig. 42.49).
The majority of fingertip avulsion injuries of the distal tip in North 
America are managed nonoperatively, though in Asia and Europe, 
there is more focus on attempted reimplantation, with success rates 
of 70% to 90%.35,36 This appears to be secondary to cultural concerns 
of missing digits, compared to a priority in the United States of rapid 
return to function. In the ED, optimizing the opportunity for a suc-
cessful reimplantation in more significant injuries should be the goal 
as these patients have less pain and better functional outcome than 
those whose digit is amputated. The patients that should be referred 
immediately to a reimplantation specialist include those with loss of 
a thumb, multiple fingers, or the fingertip, and any child with loss of 
a digit.
If reimplantation is not an option, then a hand specialist may select 
several options for closing a larger wound. Free grafts, cross- flaps, 
advancement flaps, skin grafts, and healing by secondary intention are 
all possible treatment options for these injuries. If a patient who has 
previously undergone surgery for this injury such as a cross- finger flap 
presents to the ED, extreme care must be taken to avoid tension that 
may pull apart the graft site (Fig. 42.50). It may be of benefit to call the 
surgeon before removing the dressing.
The use of antibiotics has long been debated and, although pre-
scribed for many patients with open tuft fractures with nail bed inju-
ries, studies do not demonstrate that use of antibiotics reduces the risk 
of infection in a well- cleansed wound.37 The consensus is that antibi-
otic prophylaxis (oral cephalexin 500 mg TID or oral doxycycline 100 
A B
C D
Fig. 42.46 Nail bed injury and repair. (A) Injury to eponychium prior to repair. (B) Separation of the nail plate 
from the sterile matrix with a fine scissor directly under the distal nail plate attachment. (C) The epony-
chium tissue is removed with scissor and the nail plate is removed with forceps traction. (D) Following nail 
bed repair. (Brown DJ, Jaffe JE, Henson JK. Advanced laceration management. Emerg Med Clin N Am. 
2007;25(1):83-99. Fig. 1.)
492 PART II Trauma
mg BID (for penicillin- allergic patients for 7 days) should be given for 
grossly contaminated wounds but is not necessary in clean wounds in 
immunocompetent patients.
Disposition. Immediate consultation with the hand specialist is 
needed for all but those with zone I and other minimal injuries. In the 
United States, it is rare that an isolated fingertip amputation will get 
reimplanted. If the emergency physician is not comfortable with the 
closure described, then the hand specialist should see that patient at 
the time of the initial ED visit. After the patient’s fingertip avulsion has 
been treated with coverage of the bone and tendon, the patient should 
have follow- up with the hand specialist in 7 to 10 days.
Transfer to a reimplantation center may be necessary during the 
initial ED visit. The success of reimplantation from specialized centers 
is reported to be 90% or better. Many clinicians are concerned about 
delay to reimplantation after amputation. Recent studies have shown 
that the success rate of reimplantation remains above 90% whether 
done immediately or even with an overnight delay from injury to sur-
gery.38 The most common residual subjective symptom reported is cold 
intolerance to the tip of the finger. Other undesirable outcomes include 
infection, insensitivity, abnormal cosmetic appearance, and decreased 
range of motion.
Degloving Injuries
Degloving injuries and ring avulsion injuries (traumatic removal of a 
ring from a digit) result from trauma of a digit or the hand that pulls off 
the tissue, involving a varying degree of skin, muscle, tendons, flexor 
pulleys, and the associated neurovascular bundles (Fig. 42.51). The 
Urbaniak classification for ring avulsion injuries (Box 42.3) is helpful 
to determine treatment and prognosis. The more severe the injury, the 
less likely hand specialists are to attempt repair rather than amputation 
and the more likely for complications of flap coverage, revasculariza-
tion, and reimplantation. Patients with class I injury should be seen by 
a hand specialist for assessment and wound closure. Class II or III inju-
ries needs microsurgery with immediate referral to a hand specialist 
and facility capable of performing this repair. The most important indi-
cation of success is the ability to restore adequate revascularization.39
Mutilating Hand Injuries
Severe mutilating injuries of the hand can occur from explosions, 
gunshots, crushing industrial accident, motor vehicle collision, home 
equipment or environmental activities. These dramatic wounds are 
generally associated with other traumatic injuries that can be life- 
threatening, so appropriate evaluation for trauma patients should be 
prioritized without being distracted by the injured hand. Controlling 
the bleeding from a major hand wound can generally been done with 
direct pressure, or if not successful, by the use of a pneumatic or blood 
pressure cuff. Though challenging, a physical examination should be 
done to document the remaining function and sensation, if possible. 
Assessment of the vascular system might be difficult, but evidence of 
Fig. 42.47 Fingertip amputation zones: Zone I amputations include 
pulp and distal nail which generally heal by secondary intention. Zone II, 
Bone exposed—revision amputation soft tissue flap (e.g., V- Y advance-
ment flap). Zone III involves the eponychium. Most require amputation 
of the distal phalanx at the DIP joint. (Courtesy Dr. D.A. Stearns, Depart-
ment of Emergency Medicine, Massachusetts General Hospital, Har-
vard Medical School, Boston.)
Fig. 42.48 Volar finger- tip amputation. (Courtesy of Ronald Barry, MD, 
FACS)
493CHAPTER 42 Hand Injuries
a pulse can be obtained through the use of a Doppler ultrasound or 
placement of a pulse oximeter. Immediate consultation with the hand 
specialist should be obtained after the patient is stabilized from other 
life- threatening injuries. In the ED, one dose of IV antibiotics (first- 
generation cephalosporin such as cefazolin 2 to 3 gm or vancomycin 
10 to 15 mg/kg for adults) and appropriate tetanus prophylaxis are 
indicated prior to surgical stabilization. For the surgeon, the priorities 
are to have a stable thumb or a first digit post of at least the length 
of the IP joint, to have one or preferably two opposing digits, and to 
achieve coverage of tissue with sensation for the involved functioning 
extremity.
A B
Fig. 42.49 Example of a V- Y advancement flap and an oblique triangular neurovascular island flap used for 
reconstruction of a small size pulp defect in the index and long fingers, respectively. (A) Flap design. (B) After 
advancement of flap. Direction of flap advancement as indicated by the black arrow. (Ono S, Sebastin SJ. 
Microsurgical flaps in repair and reconstruction of the hand. Hand Clin. 2017;33(3):425-441. Fig. 10.)
Fig. 42.50 Cross- finger flap. (Courtesy of Ronald Barry, MD, FACS.)
Fig. 42.51 Degloving injury in a patient who stuck her thumb in a wood 
splitter. (Courtesy Benjamin Schoener, MD. Central Michigan University 
COM.)494 PART II Trauma
Skin and Soft Tissue Injuries
Clinical Features
Lacerations to the hand and fingers are approached with more care than 
those on the proximal extremities and torso due to the numerous struc-
tures covered by minimal tissue. Knowledge of hand anatomy will assist 
when performing careful exploration of each laceration to determine if any 
structures have been injured. A full examination of the function of sur-
rounding tendons and muscles must be performed, and any abnormalities 
documented. Abnormal positioning of the hand or fingers may indicate 
a tendon injury or displaced fracture. Two- point sensation of each of the 
fingers should be tested distal to the laceration to identify possible nerve 
injury. Foreign bodies such as glass can easily be missed in the wounds, 
so identifying the risk and instructing patients accordingly is important. 
Finally, all rings or constricting material should be removed on the injured 
hand to avoid swelling with resulting vascular congestion.
Diagnostic Testing
X- rays of the hand or digit with the laceration may help if there is con-
cern for a foreign body, or to determine if there is air in the joint from 
a laceration.
Management
Initial assessment of any laceration includes direct visualization and 
complete examination of the muscle, tendon, and neurovascular func-
tions of the hand and fingers. Determination of tetanus vaccination 
status should be assessed, and immunization updated if appropriate.
Each laceration should be explored to assure there is no injury to 
the tendon, joint or neurovascular bundle. If there is a laceration near 
a joint, the wound should be explored to determine if there is intru-
sion into the joint space, which would require extensive washout to 
decrease the chance of infection. If the laceration is over any region 
with a tendon, it is advised that exploration should occur while care-
fully examining the tendon moving through the entire length of its 
range of motion. A commonly missed injury is a partial tendon injury 
undiscovered because the patient’s function with formal testing may 
be normal. A partial tendon laceration could put the tendon at risk for 
further injury later.
Generally, bleeding from the digital arteries distal to the DIP joint 
can be controlled with local compression and closure of the skin. An 
artery could be tied off without complication due to the collateral cir-
culation of each digit, but this is rarely needed. Care should be taken to 
avoid tying off the accompanying digital nerve if it is intact.
Most hand and finger skin lacerations can be closed with simple inter-
rupted sutures, 4-0 or 5-0 nonabsorbable (nylon) sutures using the stan-
dard technique including everting the wound edges. Absorbable (Vicryl) 
4-0 or 5-0 suture material is used for deep layers. Care must be taken 
to avoid other structures in the hand while closing simple wounds. For 
wounds in the palm or other gapping wounds, it is difficult to approxi-
mate the wound edges due to the tension of the skin, so horizontal mat-
tress sutures may be more advantageous. Tissue adhesive can be used on 
wounds that have bleeding controlled in areas that lack tension and if no 
underlying structures would be exposed to the adhesive.
Laceration of the joint capsule should be discussed with the hand 
specialist in the ED because many are brought to the operating room 
for an extensive wash- out. After expert consultation, distal joints may 
be copiously irrigated and closed within the ED with close follow- up. 
A first dose of empirical antibiotics (cephalexin 500 mg BID for 7 days) 
can be discussed with the consultant. Similarly, lacerations of the flexor 
tendons should be discussed with and cared for by the hand special-
ist. If delayed primary repair is recommended by the consultant, the 
wound should be copiously irrigated, then the skin should be closed 
with 5-0 non- absorbable sutures. The hand should be splinted to mini-
mize stretch on the flexor tendon. In a dorsal blocking splint, the splint 
is placed on the dorsal side of the extremity with the wrist flexed at a 
30- degree angle, the MCP joints at 70 degrees of flexion, and the IP 
joints in extension, flexed at only 15 degrees. Follow- up with the hand 
specialist should be arranged within a few days to reduce contraction 
of the tendons more proximally.
Laceration of the Extensor Tendon. Evaluation of a laceration 
over the extensor tendon includes obtaining visualization of the 
underlying tendon throughout its entire range of motion. If a tendon 
is cut by less than 50%, functional testing, even against a force, might 
be normal. It has been shown that a laceration of less than 50% can 
heal with conservative treatment including overlying wound care and 
splinting. It is very important to trim any minimal tags to allow for 
the gliding mechanism of the extensor tendon. After discussion with 
the hand specialist, an emergency physician can repair a complete or 
near- complete extensor tendon laceration. A nonabsorbable suture 
material should be used, 4-0 in the finger and 3-0 in the hand to repair 
the tendon. In thin tendons, a figure- of- eight or mattress stitch can be 
used or modified Bunnell or Kessler stitch in larger tendons that have 
enough width to hold the tension of the suture (Fig. 42.52).
Disposition
All lacerations of the hand should be followed up by a provider to 
assess for possible infection. If there is any concern for an infection, 
appropriate antibiotics should be started, such as a first- generation 
cephalosporin (cephalexin 500 mg BID) or doxycycline (100 mg BID) 
for 7 days for patients with true penicillin anaphylaxis. Due to the close 
association between the tissue of the digits and the bony phalanxes, 
osteomyelitis is a risk for any patients with an infected wound in the 
tissue of the digits. All patients with a potential tendon or joint lacera-
tion need close follow- up with a hand specialist, ideally within 3 days.
Clenched Fist Injuries
Specific laceration injuries to the hand include the clenched fist inju-
ries, tooth- knuckle injuries or fight bites in which a patient develops a 
laceration from the impact of hitting another human’s mouth or teeth 
with a fist. This must be considered in any laceration on the dorsum of 
the hand and lead to a concern for intrusion into a joint, tendon sheath 
or even bone. The delay in treatment, deep wounds, and PIP joint inju-
ries significantly increases the complication rate. In a meta- analysis of 
these wounds, greater than one- third of patients had tenosynovitis, 
joint infections or osteomyelitis.40 Treatment should include coverage 
for Staphylococcus, Streptococcus viridans, and Eikenella corrodens. For 
patient with an infection who will be admitted, we recommend the use 
of broad- spectrum antibiotics such as ampicillin/sulbactam (3 g IV 
q6 hours) due to the aerobic and anaerobic, polymicrobial nature of 
these infections. For outpatient therapy, one can also use amoxicillin/
clavulanate 875 BID or clindamycin 600 mg q8 hours for 7 days plus a 
fluroquinolone (i.e., levofloxacin 500 mg daily) in a patient with true 
penicillin anaphylaxis. In addition, exploration and surgical wash- out 
BOX 42.3 Urbaniak Classification for Ring 
Avulsion Injuries
 • Class I: Circulation adequate
 • Class II: Circulation inadequate
 • Class III: Complete degloving injury or complete amputation
495CHAPTER 42 Hand Injuries
of the wound is indicated, due to the high incidence of joint or tendon 
sheath intrusion.41
INFECTIOUS DISORDERS OF THE HAND
General Hand Infections
Infections of the hand occur due to direct inoculation and open 
wounds. In one large study, almost 50% of infections in the hand had 
cultures positive for MRSA organisms, with increasing resistance to 
clindamycin and levofloxacin, especially in patients with intravenous 
drug abuse (IVDA) and patients with immunocompromised condi-
tions such as diabetes mellitus.42
Paronychia
A paronychiais acute inflammatory changes or infectious changes 
in the skin in or under one of the nail folds that line the nail bed 
(Fig. 42.53). This is often due to trauma or a foreign body, such as 
a dry cuticle or open wounds from picking and pulling of skin in 
this region. Incision and drainage should be accomplished using gen-
eral principles, including inspection for removal of any foreign body, 
opening of abscess to allow drainage, and avoiding damage to the nail 
bed or plate. The nail fold is elevated by blunt dissection or scalpel 
to release the purulent fluid while avoiding damage to the nail plate 
and nail matrix. On occasion, if the edge of the nail is the inciting 
irritant, a partial nail plate excision could be done to eliminate the 
cause and allow the nail to grow back in a corrected manner. With 
adequate incision, no treatment with postprocedural antibiotics is 
Mattress Figure 8 Modified
Bunnell
Modified
Kessler
A B
C D E
MGH
Modified
Bunnell
Modified
Krackow-Thomas
Running
Initiating the
Interlocking Horizontal
Mattress suture
Running/Interlocking
Horizontal Mattress
 suture
Fig. 42.52 (A–E) Demonstration of extensor tendon injury repair techniques. (A: From Newport ML, Williams 
CD: Biomechanical characteristics of extensor tendon suture techniques. J Hand Surg Am. 1992;17:111-
119, with permission from The American Society for Surgery of the Hand; B: from Howard RF, Ondrovic 
L, Greenwald DP: Biomechanical analysis of four- strand extensor tendon repair techniques. J Hand Surg 
Am. 1997;22:838-842, with permission from The American Society for Surgery of the Hand; C–E: from Lee 
SK, Dubey A, Kim BH, et al. A biomechanical study of extensor tendon repair methods: introduction to the 
running- interlocking horizontal mattress extensor tendon repair. J Hand Surg Am. 35:19–23, 2010, with per-
mission from The American Society for Surgery of the Hand.)
496 PART II Trauma
appropriate.43 If there is no abscess to incise, the digit can be soaked 
with 1% acetic acid and warm water for 15 minutes 2 to 4 times daily 
to decrease the bacterial count of Pseudomonas aeruginosa and other 
infectious agents.44 Topical mupirocin daily for 7 to 10 days may also 
be used in combination with a topical steroid at night to decrease 
inflammation.
Chronic paronychia can be caused by topical irritation or hyper-
sensitivity reaction. Treatment can include topical steroid medications 
such as triamcinolone cream once to twice per day for three months. If 
the patient indicates that the paronychia has been present for months, 
it is likely to be a fungal infection. Systemic medications for suspected 
fungal irritants are not useful because the irritation is topical and not 
due to an actual tissue infection. The patient should be informed to 
stop soaking it, keep it dry, and apply a topical antifungal (terbinafine 
1% cream twice daily). A hand specialist could be consulted for marsu-
pialization or other surgical treatments if necessary.
Onychomycosis
Onychomycosis is a mycotic infection within the nail rather than the 
nail folds and should be treated with antifungal medications for an 
extended period of time. The classic finding is thickening of the nail 
itself (hyperkeratosis) from invasion of the fungi. Though antifungal 
medication such as oral fluconazole 150 mg to 450 mg weekly could be 
started by the emergency clinician, the long- term nature of the therapy 
and possible systemic complications makes it more appropriate for a 
primary care provider to develop the treatment plan.
Felon
Felon is an infection of the pulp space of the fingertip, caused by pen-
etrating trauma such as a diabetic lancet, though often no specific 
known source is identified (see Fig. 42.53). The fibrous septae of the 
fingertip create small compartments which restrict swelling, leading to 
increased pressure, nerve and vascular compression, and then necrosis 
of the tissue. This explains the severe pain associated with this infection 
and the increased risk of osteomyelitis and tenosynovitis. Oral antibi-
otics (cephalexin 500 mg TID for 7 days) and warm soaks can be used 
when this fingertip infection is at the stage of cellulitis, but when there 
is an abscess, incision and drainage is necessary. The incision should 
be along either the lateral side of the tuft, along the flexion crease, just 
below the nail edge dorsal to the neurovascular bundle and distal to 
A B
C
Fig. 42.53 (A) Paronychia of patient’s index finger. (B) Felon. (C) Onycholysis. The detached nail plate is 
white in color. (A: Courtesy of Angela Gregory, MD and Ian Keck, DO. Central Michigan University COM); B: 
Rerucha, Caitlyn et al. Acute hand infections. Am Fam Phys. 99(4):228- 236, 2019; Fig 4.; C: Tosti A. Diseases 
of hair and nails. In: Goldman L, Schafer AI, eds. Goldman- Cecil Medicine, ed 26. Philadelphia: Elsevier; 
2019:2655-2664. Fig. 413-15.)
497CHAPTER 42 Hand Injuries
the DIP joint and pulley system, or midline on the dorsum of the tuft. 
Incisions to avoid include one around the edge to the tip of the finger 
and a double longitudinal incision pattern on the same side, because 
both will destabilize the fingertip.
Herpetic Whitlow
Clinical Features. Herpetic whitlow is a cutaneous herpes simplex 
virus (HSV) infection seen on the fingers from contact with oral 
lesions via self- inoculation (thumb sucking) or seen in health care 
workers such as respiratory therapists from oral care of intubated 
patients.
Differential Diagnoses. Herpetic whitlow is sometimes confused 
with a paronychia or felon. Special attention should be given to the 
presence of vesicular lesions which are not typically seen with a 
paronychia or felon.
Diagnostic Testing. Diagnosis is made through viral culture or PCR 
assay of the unroofed lesions.
Management. No antiviral therapy is indicated in immunocompetent 
patients because the disease is generally self- limited, though oral 
acyclovir (800 mg BID) or valacyclovir (500 mg BID) for 7 days may 
be used to decrease the infectivity of those whose infection may cause 
a risk to others, such as health care workers. If the patient has systemic 
infectious signs, IV acyclovir may be needed for treatment.45
Purulent Flexor Tenosynovitis
Clinical Features. The most common symptom of purulent flexor 
tenosynovitis is fusiform swelling of the digit, with direct tenderness 
over the flexor sheath as the most specific finding (Fig. 42.54). The 
findings described by Dr. Allen B. Kanavel a century ago remain the 
cardinal symptoms of patients with flexor tenosynovitis (Box 42.4). 
Diffuse swelling is often labeled the most common sign, however 
it is very nonspecific. Though both are independent predictors of 
infectious tenosynovitis, we find that pain with passive extension is a 
more specific sign compared to tenderness along the tendon sheath as 
the latter is found in most patients with cellulitis.45 The EM physician 
should remain vigilant for patients with tenosynovitis because the 
initial presentation may be subtle and Kanavel findings are sensitive, 
but not very specific, for this infectious process. It has been found that 
direct inoculation is the primary infectious process. Less than 15% of 
all patients in one review had comorbid conditions, indicating this 
condition is generally found in immunocompetent hosts.46
Differential Diagnoses. One should also consider trigger finger 
(stenosing tenosynovitis), Dupuytren contracture, tendon injury, 
inflammatory arthritis, simple cellulitis, or underlying paronychia or 
felon when evaluating a patient with suspected infectious tenosynovitis.
Diagnostic Testing. Plain films do not appear to distinguish 
between tenosynovitis and other general hand infections, though they 
are used to assess for subcutaneous air in the tissue.47 New studies are 
demonstrating the use of ultrasound for diagnosis of inflammatory 
and infectious tenosynovitis; though the specificity is low, the negative 
predictive value makes this modalityuseful.48 The addition of an ESR 
may help guide the diagnosis as well, though other inflammatory 
markers were not found to be statistically sensitive.45
Management. Skin contaminants of gram- positive bacteria are 
typical in these infections, making early use of antibiotics appropriate. 
Initial treatment with vancomycin 10 to 15 mg/kg IV (with subsequent 
dosing per pharmacy adjusted for renal insufficiency) is appropriate 
in the emergency department, without waiting for surgical cultures, 
because early antibiotics use appears to decrease the serious 
complications associated with this disease. Definitive treatment 
remains surgical wash- out, so admission for operative management 
by a hand specialist is necessary. A systematic review showed that IV 
antibiotics and catheter wash- out, rather than open surgical drainage 
of the tendon sheath, improved outcomes. The most common outcome 
noted variable range of motion, which was clearly linked to how early 
the diagnosis was made in the course of the disease.46
Deep Space Infections
Clinical Features. Deep space infections of the volar side of the 
hand are found under the flexor tendons but above the interosseous 
muscles in the thenar, hypothenar, and mid- palmar spaces. The deep 
dorsal subaponeurotic space is between the aponeurosis of the extensor 
tendons and their attachment distally while the interdigital spaces are 
between the distal metacarpal heads of each digit. Each may present 
with distinctive complaints due to the involved tendons and muscles 
that course through and around the spaces. Given the variability of the 
components of the compartments, there are no classic descriptions of 
each. Initially, the patient will complain of aching pain and decreased 
movement of the digits without systemic symptoms.
Differential Diagnoses. Consider compartment syndrome in patients 
with exceptional swelling, disproportional pain, and neurovascular 
compromise.
Diagnostic Testing. Ultrasound and MRI are more sensitive than 
CT scan and often are needed to make the diagnosis early in the course 
of the disease.49 For patients who are ill with systemic symptoms with 
signs such as fever, blood cultures should be obtained prior to antibiotic 
administration.
Management. The classic infectious organisms include Staphylococcus 
aureus and Streptococcus spp. Because there has been an increase in 
gram- negative and atypical organisms, the use of early broad- spectrum 
Fig. 42.54 Flexor tenosynovitis of the third digit. (Courtesy of Catherine 
Champagne, DO and Dan Coffey, DO; Central Michigan University COM.)
BOX 42.4 Kanavel Signs
 1. Exquisite tenderness over the course of the sheath, limited to the sheath
 2. Flexion of the finger
 3. Exquisite pain on extending the finger, most marked at the proximal end
 4. The whole of the involved finger is uniformly swollen (fusiform swelling)
498 PART II Trauma
antibiotics such as vancomycin (10 to 15 mg IV followed by pharmacy 
dosing) and piperacillin- tazobactam (3.375 g IV q6 hours) can decrease 
extension of the infection or complications. Early consultation with 
a hand specialist in the ED is imperative to assist with the decision on 
whether the patient requires surgical intervention.
Skin and Soft Tissue Disorders
Onycholysis
Onycholysis is the separation of the nail from the nail plate at the distal 
end and slowly separating more proximally (see Fig. 42.53). The etiol-
ogy can be as simple as trauma or fungal infection, but consideration 
should be given to systemic diseases such as thyroid disease, psoriasis, 
and certain chemotherapeutic agents.50
High- Pressure Injury
High- pressure injection injuries occur when a finger is accidentally 
placed over the nozzle of a paint, oil, water or other high- pressure 
injector, often when it is being cleaned. Because the injection comes 
from a small pin, the entrance wound to this injection is unassuming 
and often the damage underestimated. The caustic chemical injected 
and the tissue destruction from the high pressure will cause increasing 
swelling, leading to ischemia. This creates a compartment syndrome, 
often within the flexor tendon sheath, which will require surgical 
decompression and wash- out (Fig. 42.55). High- pressure injections of 
air, water, and some medications do not seem to cause the same severe 
damage. Management recommendations for the patient in the ED 
include administering the first dose of IV antibiotics (first- or third- 
generation cephalosporin such as cefazolin 1 to 2 g IV or ceftriaxone 1 
to 2 g IV) and pain control. Any injection injury should have emergent 
consultation in the ED by the hand specialist, who will determine if 
exploration of the wound is needed. Surgical débridement, if needed, 
has been found to decrease the rate of amputation if done within 6 
hours.51
Ganglion Cysts
In the ED, patients present with cysts due to increased pain, often 
blamed on acute trauma. Typical ganglion cysts are mobile firm cysts 
filled with mucin that develop adjacent to joints and tendons, most 
commonly on the dorsal or volar surface of the wrist. Retinacular gan-
glion cysts are found on the volar finger at the proximal phalanx or 
MCP joint and are generally much smaller and less mobile, associated 
with the first two flexor tendon pulleys. Multiple theories have been 
formed to explain the development of ganglion cysts, but they do not 
seem to be related to direct trauma. The dorsal DIP joint ganglion cyst, 
known as a mucoid cyst, is often associated with osteoarthritis. Mucoid 
cyst walls are thinner and more likely to erode or rupture, which can 
lead to infection. These do not appear to connect directly to the joint, 
so the typical antibiotic treatment for skin infection is adequate.
Aspiration of the cyst may improve the patient’s pain symptoms, but 
there is more than a 50% recurrence rate. Even with the use of ultra-
sound for guidance in the aspiration of the cyst, there is a high recur-
rence rate.52 Surgical removal or excision has a much lower recurrence 
rate (average 6% noted in a meta- analysis).53 Given the high recurrence 
rate and option for surgical removal, we recommend that most gan-
glion cysts not be aspirated in the emergency department. Injection of 
corticosteroids into the DIP joint space reduced ganglion cysts without 
complication but had a 50% recurrence rate54 and other studies have 
shown that direct aspiration with injection of steroids had a slightly 
lower recurrence rate. Historically, these cysts were “popped” through 
direct compression from a “slap of the family bible.” Based on an inter-
esting study using internet videos with survey follow- up, direct blunt 
force successfully disrupted ganglion cysts and less than 50% had a 
recurrence at 2- year follow- up.55
A B C
D E
Fig. 42.55 High- pressure injection injury. (A and B) Index finger following injection of paint thinner. There is a 
small wound from the paint thinner and associated pallor throughout finger and swelling seen on the lateral 
view. (C) Following decompression and débridement of right index finger. Return of blood flow is demon-
strated. The wound was left open without formal closure. (D and E) Follow- up postoperative pictures showing 
healed wound and functional range of motion. (Cannon TA. High- pressure injection injuries of the hand. Ortho 
Clin N Am. 2016;47(3):617-624. Fig. 2.)
499CHAPTER 42 Hand Injuries
Dupuytren Contracture
Dupuytren contracture is the result of fibrosis of the palmar fascia 
which causes the tightening of an area of fascia, creating a cord 
that limits the motion of a specific finger or area of the palm. In 
the ED, diagnosis can be made based on the clinical findings as 
shown in the Figure 42.56. Treatment is limited to appropriate 
referral to a hand specialist who may use percutaneous needle 
aponeurotomy, collagenase injections, or open surgery to treat this 
contracture.56
Acknowledgments
The authors would like to acknowledge the assistanceof Ronald Barry, 
MD, FACS in the preparation of this chapter, including providing many 
of the images.Fig. 42.56 Dupuytren contracture as demonstrated with typical nodule- 
like and cordlike changes in the ulnar digits resulting in the characteristic 
flexion contractures. (Kelly B Isaacs JE. Dupuytren contracture. In: Miller 
MD, Hart JA, MacKnight JM. Essential Orthopaedics, ed 2. Philadelphia: 
Elsevier; 2020:341-344. Fig 88.2. Courtesy of Bobby Chhabra, MD.)
The references for this chapter can be found online at ExpertConsult.
com.
http://ExpertConsult.com
http://ExpertConsult.com
499.e1
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 C H A P T E R 4 2 : Q U E S T I O N S A N D A N S W E R S
 1. Which of the following demonstrates the motor function of the 
median nerve?
 a. Extending the hand at the wrist
 b. Making an “OK” sign with the thumb and first finger
 c. Pulling the thumb across the palm to touch the little finger
 d. Spreading out the fingers of the hand
Answer: B. Making an “OK” sign with the thumb and first finger. The 
median nerve controls the flexors of the thumb and index finger that 
allow the hand to make the “OK” sign. The ulnar nerve innervates the 
adductor pollicis that pulls the thumb across the palm so it can touch 
the little finger and innervates the interosseous muscles to allow the 
hand to spread out or abduct the fingers. The radial nerve innervates 
the extensor carpi radialis longus and the other wrist extensors.
 2. A 25- year old woman comes to the emergency department com-
plaining of hitting the tip of her finger on a basketball. She has 
difficulty extending the tip of her ring finger. What is the most 
appropriate splinting technique for this injury?
 a. Aluminium volar splint with finger in position of function
 b. Dorsal blocking splint with DIP at 15 degrees of flexion
 c. Stack splint with extension of distal phalanx
 d. Ulnar gutter splint to include ring finger to the tip
Answer: C. Stack splint with extension of distal phalanx. The descrip-
tion of the injury is consistent with a mallet finger injury, where the 
distal extensor tendon has pulled off the proximal end of the distal pha-
lanx. The premolded Stack splint keeps the distal phalanx in extension 
and can remain in place for 6 weeks for healing. The position of com-
fort for the finger in an aluminium volar splint is with the PIP and DIP 
at approximately 10 to 15 degrees of flexion, not complete extension as 
needed to allow the tendinous insertion to reattach. A straight alumin-
ium splint could be used on the dorsal surface of the finger to keep the 
DIP joint straight. A dorsal blocking splint is used for flexor tendon 
lacerations or ruptures, preventing any extension in the digit and hand 
to decrease the contraction of the flexor tendon, which will increase 
the extensor tendon strain. The ulnar gutter splint provides much more 
extensive immobilization than is necessary for this injury.
 3. After cutting her hand while washing a drinking glass, a patient 
complains of a laceration to her finger. In which location of the pal-
mar hand surface is this laceration most likely to cause a lack of 
flexion to the index finger PIP joint?
 a. Base of the thenar eminence
 b. Distal end of the middle phalanx
 c. Proximal end of the proximal phalanx
 d. Volar crease of the MCP joint
Answer: D. Volar crease of the MCP joint. The flexor digitorum super-
ficialis (FDS) functions to flex the finger at the PIP joint. It attaches 
at the proximal end of the middle phalanx as well as the distal end of 
the proximal phalanx. A laceration along the volar crease of the MCP 
joint will cut the FDS tendon when the fingers are in extension and 
reduce the flexion of the PIP joint. The flexor digitorum profundus 
(FDS) inserts at the proximal end of the distal phalanx. Cutting the 
finger from the mid aspect of the middle phalanx distally results in an 
injury to the FDP and an inability to flex at the DIP joint. There are no 
tendons running within the thenar webspace.
 4. Which of the following is the most disease- distinguishing finding of 
a patient with pyogenic flexor tenosynovitis?
 a. Involved finger is held in flexion
 b. Pain on extension of the finger
 c. Tenderness over the tendon sheath
 d. Uniform swelling of the involved finger
Answer: B. Pain on extension of the finger. All of these findings are 
components of Kanavel’s findings for infectious tenosynovitis. Even 
though uniform involved swelling has been listed as the most common 
sign in some studies, this is misleading as swelling is the most com-
mon sign in many hand problems and is very nonspecific. What most 
commonly separates purulent flexor tenosynovitis from other finger 
infections is pain with passive extension. Many patients with even just 
cellulitis have pain with palpation over the area of infection on the fin-
ger, so this does not distinguish it well. Only half of the patients diag-
nosed with pyogenic flexor tenosynovitis have all of Kanavel’s findings.
 5. A patient presents after a fist fight with a puncture wound to his 
hand. Which description of the presentation has the best prognosis?
 a. Fingertip penetration
 b. Delay in treatment
 c. Depth of the wound
 d. Involvement of joint
Answer: A. Fingertip penetration. The three factors that have been 
found to worsen the prognosis for a “fight bite” injury are delay in iden-
tification and treatment of the wound, an increase depth of the wound 
as it is more likely to include the tendon, and intrusion into the joint 
of the tooth. A puncture wound of the fingertip is much less likely to 
create a significant infection due to the close septae that decrease the 
likelihood of spreading bacteria in an open wound.
 
	42 - Hand Injuries
	Anatomy
	Surface Anatomy and Skin
	Skeletal Anatomy and Ligaments
	Musculature and Tendons
	. The intrinsic hand muscles include the muscles of the thenar and hypothenar eminences as well as the adductor pollicis, lumbri...
	. The extrinsic hand muscles are those that originate proximal to the wrist and insert within the hand. Most extrinsic hand musc...
	. The extensors tendons pass through the dorsum of the wrist at 6 different compartments and are innervated by the radial nerve ...
	. The anterior forearm contains muscles responsible for flexion of the wrist, hand, and digits and can be divided into an anteri.... The digital flexor sheath of the hand is a closed system of synovial membranes that is divided into membranous and retinacular...
	Blood Supply
	. The radial and ulnar arteries are primarily responsible for blood supply to the hand. The radial artery courses through the an...
	Venous and Lymphatic System
	Innervation and Sensory Systems
	Regional Blocks
	Digital Block
	Metacarpal and Transthecal Blocks
	Wrist Blocks
	. The radial artery at the volar surface of the wrist is palpated. Immediately lateral (radial) to this region, after aspirating...
	. The tendon of the flexor carpi radialis at the volar surface of the wrist is palpated. The needle is inserted over the median ...
	. The needle should be inserted between the ulnar artery and the flexor carpi ulnaris tendon and advanced approximately 1 cm. If...
	Splinting
	Ring Removal
	Specific Hand Injuries
	Phalanx and Metacarpal Fractures
	Clinical Features
	Differential Diagnoses
	Diagnostic Testing
	Management
	Phalanx Fractures
	Distal Phalanx Fractures
	Clinical Features
	Differential Diagnoses
	Diagnostic Testing
	Management
	Middle Phalanx Fractures
	Clinical Features
	Differential Diagnoses
	Diagnostic Testing
	Management
	Proximal Phalanx Fractures
	Clinical Features
	Differential Diagnoses
	Diagnostic Testing
	Management
	Metacarpal Fractures
	Clinical Features
	Differential Diagnosis
	Diagnostic Imaging
	Management
	Thumb Fractures
	Clinical Features
	Differential Diagnoses
	Diagnostic Testing
	Management
	Joint Injuries
	Clinical Features
	Differential Diagnoses
	Diagnostic Testing
	Management
	Interphalangeal Joint Injuries
	Clinical Features
	Differential Diagnoses
	Diagnostic Testing
	Management
	Metacarpophalangeal Joint Injuries
	Clinical Features
	Differential Diagnoses
	Diagnostic Testing
	Management
	Carpometacarpal Joint Injuries
	Clinical Features
	Differential Diagnoses
	Diagnostic Testing
	Management
	Thumb Dislocations and Ligamentous Injuries
	Clinical Features
	Differential Diagnoses
	Diagnostic Testing
	Management
	Tendon Injuries
	Extensor Tendon Injuries
	Clinical Features
	. This zone includes the distal phalanx and DIP joint. Terminal tendon disruption from sudden flexion of the extended DIP joint ...
	. Injuries occur over the middle phalanx and are usually due to a laceration. Rarely, a mallet deformity will form from a lacera...
	. Injuries in this zone involve the PIP joint and the central slip. Boutonnière injury (flexion at the PIP joint with hyperexten...
	. This zone includes injuries over the proximal phalanx. Like in zone II, injuries usually occur from lacerations. The tendon is...
	. Injuries at this zone involve the sagittal band at the MCP joint. The most common injury is to the radial sagittal band of the...
	. Injuries at this zone occur over the metacarpals, most frequently secondary to lacerations. Complete lacerations are often mis...
	. Lacerations over the carpals and extensor retinaculum account for most injuries at this zone, though injuries may also occur w...
	Differential Diagnoses
	Diagnostic Testing
	Management
	. Most mallet finger injuries are successfully treated with immobilization, though injuries accompanied by fracture dislocations...
	. Incomplete lacerations can be managed with simple closure and splinting of the DIP in extension for 2 weeks. Complete lacerati...
	. Central slip disruptions (boutonnière injuries) are treated by splinting the PIP joint in extension for 4 to 6 weeks followed ...
	Zone IV Extensor Injuries Management
	. Stable sagittal band injuries (type I) can be treated with buddy or dynamic taping for 3 to 4 weeks. Acute injuries with sublu...
	. Clean, complete tendon lacerations may be repaired by an EM physician, though we recommend discussion with a hand specialist f...
	. If there is no need for immediate surgical intervention (such as gross contamination), wounds should be thoroughly irrigated f...
	Disposition
	Flexor Tendon Injuries
	Clinical Features
	Differential Diagnoses
	Diagnostic Studies
	Management
	Disposition
	Trigger Finger
	Clinical Features
	Differential Diagnoses
	Diagnostic Testing
	Management
	Finger and Nail Bed Injuries
	Nail Bed Injuries
	. The nail bed is frequently injured in a manner that ranges from minimal to severe. Injury occurs after direct trauma to the fi...
	. When evaluating a patient with a suspected nail bed injury, the EM clinician should also consider an underlying tuft fracture,...
	. Imaging is needed to determine if there is fracture of the finger tuft. PA, lateral, and oblique radiographs will identify a f...
	. For a subungual hematoma covering greater than 50% of the nail bed, the typical practice is to trephinate, or create an openin...
	. The injuries resulting in subungual hematomas with non-­displaced fractures can be followed up by primary care physicians as m...
	Amputations
	Fingertip Amputations
	. Amputations of the fingertips are common, most often occurring in children. These injuries can result in macerated tissue, but...
	. When caring for a patient with a digit amputation, one should consider associated foreign bodies, proximal fractures, ligament...
	. Standard 3-­view x-­rays of the affected digit should be performed
	. Initial management includes assessment of the wound, control of bleeding, and thorough irrigation of the injury without furthe...
	. Immediate consultation with the hand specialist is needed for all but those with zone I and other minimal injuries. In the Uni...
	Degloving Injuries
	Mutilating Hand Injuries
	Skin and Soft Tissue Injuries
	Clinical Features
	Diagnostic Testing
	Management
	. Evaluation of a laceration over the extensor tendon includes obtaining visualization of the underlying tendon throughout its e...
	Disposition
	Clenched Fist Injuries
	Infectious Disorders of the Hand
	General Hand Infections
	Paronychia
	Onychomycosis
	Felon
	Herpetic Whitlow
	. Herpetic whitlow is a cutaneous herpes simplex virus (HSV) infection seen on the fingers from contact with oral lesions via se...
	. Herpetic whitlow is sometimes confused with a paronychia or felon. Special attention should be given to the presence of vesicu...
	. Diagnosis is made through viral culture or PCR assay of the unroofed lesions
	. No antiviral therapy is indicated in immunocompetent patients because the disease is generally self-­limited, though oral acyc...
	Purulent Flexor Tenosynovitis
	. The most common symptom of purulent flexor tenosynovitis is fusiform swelling of the digit, with direct tenderness over the fl...
	. One should also consider trigger finger (stenosing tenosynovitis), Dupuytren contracture, tendon injury, inflammatory arthriti...
	. Plain films do not appear to distinguish between tenosynovitis and other general hand infections, though they are used to asse...
	. Skin contaminants of gram-­positive bacteria are typical in these infections, making early use of antibiotics appropriate. Ini...
	Deep Space Infections
	. Deep space infections of the volar side of the hand are found under the flexor tendons but above the interosseous muscles in t...
	. Consider compartment syndrome in patients with exceptional swelling, disproportional pain, and neurovascular compromise
	. Ultrasound and MRI are more sensitive than CT scan and often are needed to make the diagnosis early in the course of the disea...
	. The classic infectious organisms include Staphylococcus aureus and Streptococcus spp. Because there has been an increase in gr...
	Skin and Soft Tissue Disorders
	Onycholysis
	High-­Pressure Injury
	Ganglion Cysts
	Dupuytren Contracture
	Acknowledgments
	References