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500 Wrist and Forearm Injuries Vanessa S. Franco and Hyung T. Kim 43 WRIST FOUNDATIONS Anatomy, Physiology, and Pathophysiology The wrist joint is broadly defined as the anatomic area from the distal radius and ulna bones of the forearm to the carpometacarpal junctions of the hand. It is anatomically and biomechanically complex, allow- ing for diverse functional capabilities. The wrist is composed of many complex articulations, including the radiocarpal, midcarpal, and distal radial ulnar joints (DRUJs), allowing for flexion, extension, abduction (radial deviation), adduction (ulnar deviation), and circumduction movements. Pronation and supination of the hand are primarily move- ments of the forearm occurring at the proximal radial ulnar joint and DRUJ. The wrist includes the distal radius, ulna, and eight carpal bones, which are arranged in two transverse rows and are commonly referred to as the carpus (Fig. 43.1). Each carpal row contains four bones. The more mobile, proximal row, listed radial to ulnar, consists of the scaphoid, lunate, triquetrum, and pisiform bones and the distal row consists of the trapezium, trapezoid, capitate, and hamate bones. The radius has three articular surfaces at the wrist—radiocarpal joint, DRUJ, and an interface with the triangular fibrocartilage complex (TFCC), also known as the articular disk. The distal radius articulates directly with the carpus via the scaphoid and lunate bones, which forms the common wrist joint. The ulna is separated from direct articulation with the proximal carpal row by the TFCC. The articular disk binds the distal ends of the radius, ulna, lunate, and triquetrum together. The DRUJ is a synovial pivot where the distal radius articulates and rotates around the relatively fixed ulna, and this joint is primarily stabilized by the TFCC. Aside from the pisiform, a sesamoid bone embedded within the flexor carpi ulnaris (FCU) tendon, the carpal bones are lined by synovium that creates a continuous capsule throughout the intercar- pal joints, distally to the metacarpal articulations. The only muscu- lar insertions that occur throughout the carpus are the origin of the abductor digiti minimi from the pisiform, and the point at which the FCU tendon inserts onto the hook of the hamate. As a result, nearly all carpal bone movements are passive, based on muscular insertions on the distal radius, ulna, and metacarpal bases. The stabilizing ligaments of the wrist are divided into two major groups, the intrinsic and extrinsic ligaments. The intrinsic ligaments interconnect the individual carpal bones, and the extrinsic ligaments link the carpal bones to the distal radius, ulna, and metacarpals. The intrinsics are named for the adjacent bones to which they connect; the most important for maintaining carpal stability are the scapholunate and lunotriquetral ligaments. The extrinsics are divided into volar and dorsal groups. The volar extrinsic ligaments are thicker and stronger than the dorsal extrinsic ligaments and are the most important in providing stability to the wrist. Between two volar ligaments over the proximal capitate, there is an area relatively devoid of ligamentous sup- port, called the space of Poirier. This space enlarges when the wrist is dorsiflexed, and an injury to the joint capsule in this region can result in significant carpal instability (Fig. 43.2). Most structures that cross the wrist joint are contained within indi- vidual compartments formed by the deep fascia of the wrist. On the dorsal surface of the wrist, the extensor tendons are divided by the extensor retinaculum into six compartments, each having a separate KEY CONCEPTS • On plain radiographs of the wrist, three distinct arcs, known as Gilula’s lines, and equal spacing between carpus bones (1–2 mm), known as paral- lelism, assist in the radiographic diagnosis of carpal injuries. • In the setting of trauma, there is a high incidence of occult fractures and soft tissue injuries of the wrist. Because of the associated risk of malunion, nonunion, posttraumatic arthritis, and avascular necrosis (AVN), splint immobilization is recommended if pain persists despite normal appearing radiographs. • Routine wrist radiographs which include anteroposterior (AP), lateral, and oblique projections, may fail to detect scaphoid fractures. • Thumb spica immobilization is recommended for suspected scaphoid and other carpal fractures. Expedited orthopedic follow- up for repeat assess- ment, radiographs, or advanced imaging (e.g., MRI, CT, or bone scan) is indicated. • Triquetral dorsal chip fractures are best seen on the standard lateral view of the wrist as a small avulsion fracture fragment, although a more oblique pronated lateral view may be necessary to visualize these types of frac- tures. • Hamate and pisiform fractures are best visualized with a carpal tunnel or reverse supinated oblique radiograph. • Lunate dislocations result in a characteristic triangular appearance of the lunate on the posteroanterior (PA) view (commonly referred to as the “piece of pie” sign) owing to rotation of the lunate in a volar direction. This rotation also is visible on the lateral view of the wrist, where the lunate appears like a cup tipped forward, spilling its contents into the palm (referred to as the “spilled teacup” sign). • A Colles fracture is a transverse fracture of the distal radial metaphysis, which is dorsally displaced and angulated. The Smith fracture is a trans- verse fracture of the metaphysis of the distal radius, with associated volar displacement and angulation. • Ulna fractures associated with radial head dislocation are commonly known as Monteggia fractures. Galeazzi fractures refer to fractures of the middle to distal third of the radius associated with injury to and dislocation of the distal radial ulnar joint (DRUJ). 501CHAPTER 43 Wrist and Forearm Injuries synovial sheath that extends proximally and distally to the retinac- ulum. On the volar surface of the wrist, the flexors of the digits and median nerve are contained within the carpal tunnel, which is formed by the flexor retinaculum superficially and its attachments to the car- pal bones. Radially, the flexor retinaculum attaches to the scaphoid tubercle and ridge of the trapezium. On the ulnar side, it attaches to the pisiform and hook of the hamate. Both the trapezoid and capitate bones form the floor of the carpal tunnel. Radially and superficially to the carpal tunnel, the flexor carpi radialis tendon crosses the wrist joint in its own compartment. The vascular supply to the wrist is provided by the radial and ulnar arteries, which join in a series of dorsal and palmar arches to supply the bones of the carpus. The intrinsic blood supply to most carpal bones enters the distal portion, leaving the proximal area, placing them at risk for devas- cularization and avascular necrosis (AVN) when fractured. This is partic- ularly true for the scaphoid, capitate, and lunate bones, which receive their blood supply commonly from a single distal vessel (Fig. 43.3). The wrist and hand are innervated by the radial, median, and ulnar nerves. The radial nerve and dorsal sensory branch of the ulnar nerve cross the dorsum of the wrist near the radial and ulnar styloids, respec- tively. The median nerve crosses within the carpal tunnel on the volar aspect of the wrist, just radial and deep to the palmaris longus tendon. The ulnar nerve is contained within Guyon canal, between the pisiform and hook of the hamate (see Fig. 43.3). In the setting of trauma, motor and sensory function of the radial, median, and ulnar nerves can be clinically assessed at the wrist and distally, based on their anatomical innervations (Table 43.1). CLINICAL FEATURES The clinical examination of the patient with a wrist injury begins with a history focusing on the mechanism of injury and location of pain. The physical examination beginswith inspection of the wrist, with the opposite uninjured wrist used as the normal reference. The range of motion, and the presence of swelling, discoloration, or obvious defor- mity should be noted. Several bony prominences serve as useful landmarks; their locations are best described in relation to the lateral and medial reference points in the wrist, the radial and ulnar styloids, respectively. Just distal to the radial styloid is the anatomic snuffbox, bordered radially by the abduc- tor pollicis longus (APL) and extensor pollicis brevis (EPB) tendons, and ulnarly by the extensor pollicis longus (EPL) tendon. The body of the scaphoid is palpable within the snuffbox and is more prominent with ulnar deviation of the wrist. Lister tubercle can be palpated on the dorsum of the wrist, just ulnar to the radial styloid. The scapholunate joint lies just distal to the tubercle and is a common site of ligamentous injury in the wrist. With the wrist in a neutral position, the capitate is palpable in a small depression found midway between the base of the middle metacarpal and Lister tubercle. Bringing the wrist into flexion can bring the lunate forward into a palpable position at this same site. Lister tubercle divides the second and third dorsal extensor compart- ments of the wrist and is also used as a primary landmark for radio- carpal arthrocentesis. On the dorsal aspect of the wrist in the ulnar direction from Lister tubercle is the DRUJ. The triquetrum is palpable distal to the ulnar styloid in the proximal carpal row and is made more prominent with radial deviation of the wrist. On the volar aspect of the wrist, the scaphoid tubercle is palpable just distal and palmar to the radial styloid. It is felt as a rounded prom- inence at the base of the thenar muscles and is more prominent when the wrist is extended. On the ulnar border of the wrist, the pisiform is palpable at the base of the hypothenar muscles, just distal to the wrist crease. In addition, approximately 1 cm distal and radial to this point, the prominence formed by the hook of the hamate can be palpated. Radial and ulnar pulses are easily palpable on the volar surface of the wrist, and the presence of adequate circulation should be assessed with all wrist injuries. DIFFERENTIAL DIAGNOSES Differential diagnoses for wrist pain depend on the mechanism of injury and the location of pain. A patient presenting with acute trau- matic ulnar- sided wrist pain should raise suspicion for fracture of the distal ulna and the adjacent carpal bones (including the hamate, triquetrum, lunate, and pisiform). Pisiform or hamate fractures may cause ulnar artery or nerve damage, so ulnar artery pulse and ulnar nerve function should be tested. Extensor carpi ulnaris (ECU) tendi- nopathy is another cause of ulnar- sided wrist pain, and may be asso- ciated with substantial pain, erythema, and tenderness with range of motion. Tenderness over the TFCC and pain with axial loading of the TFCC suggests TFCC injury. DRUJ instability should also be considered in patients with ulnar- sided wrist pain as well as the Radius Tubercle of radius Styloid process of radius Scaphoid Trapezium Trapezoid Dorsal view Ulna Styloid process of ulna Lunate Pisiform Triquetrum Hamate Capitate Metacarpals 5 4 3 2 1 CARPAL BONES Palmar view Radius Tubercle of scaphoid Styloid process of radius Scaphoid Trapezium Trapezoid Ulna Styloid process of ulna Lunate Pisiform Triquetrum Hamate Capitate 5 432 1 Hamulus of hamate Tubercle of trapezium Metacarpals Fig. 43.1 Bones of the Wrist. The wrist joint includes the distal artic- ular surfaces of the radius and ulna and the proximal and distal carpal rows. (Adapted from Netter FH. Atlas of human anatomy. 3rd ed. Teter- boro, NJ: Icon; 2003.) 502 PART II Trauma hypothenar hammer syndrome (caused by a single or repetitive blunt impact on the hypothenar eminence with injury to the hook of the hamate resulting in thrombosis of the superficial palmar arch of the ulnar artery). Acute, traumatic radial- sided wrist pain is concerning for a scaphoid fracture, as suggested by tenderness over the scaphoid or anatomic snuffbox. Fractures of the distal radius and other adjacent carpal bones should also be considered (such as the trapezium and trapezoid). Patients with de Quervain tenosynovitis exhibit radial- sided wrist pain associated with overuse. Examination classically reveals tenderness over the radial styloid and a positive Finkelstein test (described later in the chapter). Tenderness to palpation more 1 432 5 Metacarpals DORSAL VIEW PALMAR VIEW WITH FLEXOR RETINACULUM AND STRUCTURES REMOVED Ulna Interosseous membrane Palmar radioulnar ligament Palmar ulnocarpal ligament Ulnar collateral ligament Triquetrum Hamulus of hamate Palmar metacarpal ligaments Radius Superficial capsular tissue (cut) Palmar radiocarpal ligament Radioscapholunate part Tubercle of scaphoid Radial collateral ligament Tubercle of trapezium Capitate Palmar carpometacarpal ligaments Radiotriquetral part Radiocapitate part Ulnolunate part Ulnotriquetral part Flexor carpi ulnaris tendon (cut) Lunate (covered by ligament) Pisiform Pisohamate ligament Pisometacarpal ligament A B 5 4 3 2 1 Metacarpals Ulna Interosseous membrane Dorsal radioulnar ligament Dorsal ulnocarpal ligament Ulnar collateral ligament Capitate Hamate Dorsal metacarpal ligaments Radius Superficial capsular tissue (cut) Dorsal radiocarpal ligament Lunate (covered by ligament) Scaphoid Radial collateral ligament Trapezium Trapezoid Dorsal carpo- metacarpal ligaments * Triquetrum Fig. 43.2 Ligaments of the Wrist. (A) The volar extrinsic ligaments are most important in providing stability to the wrist. These include the radial collateral, radiocapitate, radioscaphoid, radiotriquetral, ulnotriquetral, capitotriquetral, and ulnar collateral ligaments. The space of Poirier (*) is a gap in the volar ligaments and the site of potential weakness. (B) The intrinsic (intercarpal) ligaments connect the individual carpal bones. The most important of these are the scapholunate and lunotriquetral ligaments. (Adapted from Netter FH. Atlas of human anatomy. 3rd ed. Teterboro, NJ: Icon; 2003.) ALGRAWANY 503CHAPTER 43 Wrist and Forearm Injuries proximal to the radial styloid suggests intersection syndrome. Pain or instability with axial loading, manipulation, and palpation of the carpometacarpal (CMC) joint indicates CMC joint pathology such as arthritis or subluxation. Many wrist injuries may cause pain in the dorsal or volar wrist. Fracture or dislocation of any of the carpal bones, the distal radius, or the distal ulna may cause dorsal- sided or volar- sided wrist pain. Perilu- nate or lunate dislocations may also present with dorsal- or volar- sided wrist pain and instability. Ganglion cysts often cause dorsal or volar wrist pain and may not always be visible or palpable on examination. Traumatic isolated dorsal- sided wrist pain should raise concern for scapholunate dissociation, as this injury is often missed. The Watson shift test combined with dedicated clenched fist radiographs are useful in assessing for this injury. Triquetral fractures, dislocations, or even fractures to the base of the third metacarpal may also cause dorsal- sided wrist pain following trauma. Kienbock disease, or AVN of the lunate, is suggested by tenderness and swelling over the lunate. In the setting of overuse, intersection syndrome and wrist extensor tendinitis should be considered in patients with dorsal- sided wrist pain, while carpal tunnel syndrome and wrist flexor tendinitis would typically cause volar- sided wrist pain. Gross deformity, swelling, and pain of the entire wrist should raise concern for radiocarpal dislocation. Arthritis and wrist sprains should be considered in differential diagnoses for patients presenting with 1 432 5 Metacarpals PALMAR VIEW WITHSTRUCTURES PASSING THROUGH AND OVER CARPAL TUNNEL Ulna Deep branch of ulnar a. and n. Hamulus of hamate Radial a. and superficial palmar branch Palmar carpal ligament (thickening of deep fascia, cut and reflected) Tubercle of scaphoid Flexor pollicis longus tendon Tubercle of trapezium Flexor retinaculum Median n. Flexor carpi ulnaris tendon Pisiform Palmar aponeurosis Palmaris longus tendon Flexor carpi radialis tendon Ulnar a. and n. Flexor digitorum profundus tendons Flexor digitorum superficialis tendons Interosseous membrane Radius Fig. 43.3 Vascular Supply to the Wrist. Note the relationship of the ligaments to the neurovascular supply to the wrist. (Adapted from Netter FH. Atlas of human anatomy. 3rd ed. Teterboro, NJ: Icon; 2003.) TABLE 43.1 Median, Radial, and Ulnar Nerve Innervations and Clinical Examination Parameter Median Radial Ulnar Innervation Pronator teres Flexor carpi radialis Palmaris longus Flexor digitorum superficialis Flexor digitorum profundus Flexor pollicis longus Prone for quadrates Opponens pollicis Adductor pollicis Superficial head FPB Brachioradialis Extensor carpi radialis longus Extensor carpi radialis brevis supinator Extensor digitorum Extensor digiti minimi Extensor carpi ulnaris Abductor pollicis longus Extensor pollicis longus Extensor pollicis brevis Extensor indicis Flexor carpi ulnaris Flexor digitorum profundus Opponens digiti minimi Abductor digiti minimi flexor Lumbricals 3 and 4 Dorsal interossei Palmar interossei Adductor pollicis Palmaris brevis Superficial head FPB Motor Thumb opposition Pincer function (thumb, index finger) Pronation “A- OK” sign Wrist extension Finger extension Supination “Thumbs- up” sign Finger abduction Finger abduction Sensory Sensation Index finger, volar tip Volar Sensation First dorsal web space Dorsal Sensation Little finger, volar tip Volar dorsal 504 PART II Trauma wrist pain in any location, but these conditions are largely a diagnosis of exclusion. DIAGNOSTIC TESTING Plain radiographs remain the cornerstone of emergent diagnosis of trauma to the wrist. Routine radiographic views include the postero- anterior (PA), lateral, and oblique projections each obtained with the wrist in neutral position. On a correctly positioned PA view of the wrist, the ulnar styloid rises from the lateral aspect of the distal ulna; the ECU tendon groove should be visualized at, or radial to, its base. The radial styloid pro- cess extends beyond the end of the articular surface of the ulna by a normal distance of 9 to 12 mm. This normal difference in length is called the radial length measurement (Fig. 43.4). There may be some degree of ulnar variance that affects the radial length measurement on a PA radiograph. The distal articular surface of the ulna may ter- minate proximal or distal to the radiolunate articulation as a result of wrist rotation, flexion, extension, anatomic variation, or injury. Neutral ulnar variance (as seen in Fig. 43.4) is described when the distal ulnar and radiolunate articular surfaces terminate at the same point. A posi- tive ulnar variance (ulnar articulation is more distal) or negative ulnar variance (ulnar articulation is more proximal) is independent of styloid size and may be associated with wrist pathology (e.g., ulnar impaction syndrome and Kienbock disease, respectively). The ulnar slant of the articular surface of the radius, referred to as radial inclination, is visible on the PA view and normally measures 15 to 25 degrees (see Fig. 43.4). Both of these measurements are important in assessing the degree of radial shortening seen in association with some fractures of the distal radius. The normal appearance of the carpus on the PA view shows an approximately equal distance (usually 1 to 2 mm) between each of the carpal bones, and opposing articular surfaces are parallel to one another (an arrangement known as parallelism). On radiographs, three smooth curves normally can be drawn along the carpal articular sur- faces, known as carpal or Gilula arcs (Fig. 43.5). Disruption of these curves or widening of the carpal spaces is an indication of carpal liga- ment disruption, instability, or fracture. The normal volar tilt of the distal radial articular surface is visible on the lateral view of the wrist and typically measures 10 to 25 degrees (Fig. 43.6). Adequacy of a lateral view of the wrist is assessed based on the relationship among the scaphoid, pisiform, and capitate (S-P-C) projections. The palmar cortex of the pisiform should project midway between the palmar margins of the distal pole of the scaphoid and cap- itate head, forming the S- P- C lateral (Fig. 43.7). The normal alignment of the distal radius with the lunate and capitate also is seen on the lat- eral view, which will show two concentric cups—the cup of the distal radius containing the lunate and the cup of the distal lunate containing the capitate. Ideally, the long axis of the radius, lunate, capitate, and third metacarpal should appear as a straight line on the lateral view, although the so- called normal alignment usually is within 10 degrees of this line (Fig. 43.8). The carpal alignment on the lateral view is defined further by the scapholunate angle, which should measure 30 to 60 degrees, and capitolunate angle, which is 0 to 30 degrees (Fig. 43.9). Abnormalities in these angles are seen in patients with carpal ligament injuries and instability. The soft tissues of the wrist also offer valuable clues to the pres- ence of underlying bony injuries. On most normal lateral radiographs of the wrist, the pronator quadratus line is visible as a linear, lucent, fat collection in the volar soft tissues just anterior to the distal radius (Fig. 43.10). Fractures of the distal radius or ulna result in a prona- tor quadratus sign representing volar displacement, anterior bowing, or complete obliteration of this line. This sign has a higher specificity than sensitivity for occult fracture, so its absence does not exclude a fracture.1,2 A positive pronator quadratus sign has also been observed in soft tissue injuries and infectious and inflammatory conditions. Many wrist injuries are occult and may not be identified or clearly characterized by routine wrist radiographs. Additional radiographic imaging of the wrist may assist the emergency clinician with diag- nosis based on the mechanism of injury and physical examination BA 9-12 mm 15-25° b a Fig. 43.4 Normal Radiographic Appearance of the Wrist on a Pos- teroanterior View. The ulnar styloid arises from the lateral aspect of the distal ulna, and the tendon groove for the extensor carpi ulnaris should be visualized at, or radial to, its base. (A) Radial length mea- surement with neutral ulnar variance. The radial styloid extends 9 to 12 mm beyond the articular surface of the distal ulna. The ulna may terminate distal, at, or proximal to, the radiolunate articulation affecting radial length measurement with a positive, neutral, or negative variance, respectively. (B) The ulnar slant of the distal radius (angle ab) normally measures 15 to 25 degrees. (From Greenspan A. Orthopedic radiology: a practical approach. 2nd ed. New York: Gower Medical; 1992.) Fig. 43.5 Carpal (Gilula’s) Arcs. On a posteroanterior radiograph of the wrist, three arcuate lines (1 to 3) can be drawn along the articular surfaces. Although small indentations at joint lines may occur, a step- off or broken arc suggests fracture, ligamentous instability, or disruption of the wrist. 505CHAPTER 43 Wrist and Forearm Injuries findings, including specific areas of tenderness. In addition to the standard PA, lateral, and oblique wrist radiographs, emergent patient- specific imaging helps delineate otherwise occult fractures or abnormal motion of the carpus resulting from ligamentous injuries. When a scaphoid fracture is suspected, a pronated ulnar deviated view of the wrist allows for better visualization of the bonealong its long axis. The carpal tunnel view is performed with the wrist hyper- extended and provides an axial volar image of bony margins. A hook of the hamate fracture is often radiographically occult and is better assessed with a dedicated carpal tunnel view. The carpal tunnel and reverse (supinated) oblique views help identify fractures involving the hook of the hamate and pisiform secondary to hypothenar wrist trauma. The clenched fist views drive the capitate proximally, causing diastasis within the scapholunate joint if ligamentous instability is present (Table 43.2). MANAGEMENT AND DISPOSITION There is a high incidence of radiographically occult wrist fractures. Thus, when radiographs are normal but significant localized pain per- sists, immobilization and a repeat examination should be arranged within 1 week. A thumb spica should be applied in the setting of sus- pected scaphoid fractures with orthopedic reassessment in 1 week. Occult fractures or soft tissue injuries may be diagnosed emergently, urgently, or on a routine basis with advanced computed tomography (CT) or magnetic resonance imaging (MRI) imaging protocols.3,4 Although advanced imaging occasionally identifies an otherwise occult injury, emergent CT or MRI wrist imaging is rarely indicated in the emergency department (ED) in lieu of splinting and arranging for orthopedic follow- up, unless expedited outpatient orthopedic fol- low- up is not possible. Carpal Injuries Scaphoid Fractures Foundations. Scaphoid fractures often occur after a fall on the outstretched hand, causing hyperextension of the wrist. These injuries are rare in skeletally immature patients because the carpus is composed entirely of cartilage at birth and remains predominantly cartilaginous until the adolescent years. Although the physis of the radius is more susceptible to injury, scaphoid fractures (with and without radial fracture) have been observed in pediatric patients. In older adults, a distal radius metaphysis fracture is more likely to occur. Scaphoid fractures are classified by their anatomic location and may be divided into three groups—fractures of the tuberosity and distal pole, waist, and proximal pole. Of these three patterns, fractures through the waist of the scaphoid are the most common (Fig. 43.11). Clinical features. Patients typically report radial- sided wrist pain distal to the radial styloid with decreased range of motion of the wrist and thumb. The physical examination reveals tenderness with palpation of the scaphoid, often within the anatomic snuffbox. For scaphoid tenderness to be elicited, a combination of maneuvers can be performed, including ulnar deviation, palpation of the scaphoid tubercle volarly, a Watson scaphoid shift test, axial compression of the first metacarpal, resisted supination of the wrist, and a positive clamp sign (subjective radial pain caused by a thumb- index finger pinch on both sides of the wrist). Except for the absence of snuffbox tenderness, physical examination findings lack accuracy to effectively diagnose or exclude scaphoid fractures, and no validated clinical decision rules exist. Diagnostic testing. Radiographic imaging remains the cornerstone for the evaluation of acute wrist trauma, but radiographic diagnosis of scaphoid fractures is challenging. An additional ulnar- deviated PA Volar Dorsal 10-25° a b Fig. 43.6 Normal Radiographic Appearance of the Wrist on a Lat- eral View. The distal radius has a normal volar tilt (angle ab) of 10 to 25 degrees. (From Greenspan A. Orthopedic radiology: a practical approach. 2nd ed. New York: Gower Medical; 1992.) S P C Fig. 43.7 Normal S- P- C (Scaphoid- Pisiform- Capitate) Lateral View of the Wrist. The palmar cortex of the pisiform (P) is shown bisecting the line between the palmar aspect of the scaphoid (S) and capitate (C) bones. <10° Fig. 43.8 Normal Relationship of Carpal Bones on a Lateral Radio- graphic View. The concavity of the radius and lunate and convexity of capitate form three C- shaped areas (stippled) along a straight line that runs through the central axis of these bones. 506 PART II Trauma view of the wrist may assist with fracture visualization. A visible bony lucency or cortical disruption may be absent, and a more subtle change, such as bowing, obliteration, or displacement of the scaphoid fat pad may be the only visible clue that a wrist injury is present. However, these signs are not reliably present, and plain radiographs obtained soon after injury may fail to detect a distinct fracture. While bone scintigraphy has the highest sensitivity for scaphoid fractures, this modality suffers from a lower specificity, resulting in a large number of false positives.4 There is some evidence suggesting ultrasound may be more accurate in diagnosing scaphoid fractures than X- ray,5 but other studies show mixed results.6,7 Thus, ultrasonog- raphy may be a useful adjunct for the diagnosis of scaphoid fractures for those clinicians with sonographic proficiency, but this method still requires external validation. CT and MRI imaging permit the diagno- sis of most radiographically occult scaphoid fractures. Despite its high cost and variable availability, MRI has greater sensitivity for diagnos- ing scaphoid fractures and soft tissue injuries than CT.3 Despite exten- sive studies and multiple adjunct imaging modality options, emergent advanced CT or MRI protocols to rule out scaphoid fractures remain investigational and we do not recommend their routine use in the ED. Management and disposition. To avoid complications associated with delayed diagnosis, such as occult fracture displacement and AVN, patients with suspected scaphoid fracture should have thumb spica immobilization placed in the ED with orthopedic follow- up within Scapholunate angle Capitolunate angle 30-60° 3MC C S L R In normal wrist the scapholunate angle is between 30° and 60° In normal wrist the capitolunate angle is between 0° and 30° 3MC C S L R 0-30° 3MC = third metacarpal bone C = capitate S = scaphoid L = lunate R = radius A B Fig. 43.9 (A) The normal scapholunate angle is formed by the intersection of the longitudinal axes of the scaphoid and lunate and normally measures 30 to 60 degrees. (B) The normal capitolunate angle is formed by the intersection of the capitate and lunate central long axes and normally measures 0 to 30 degrees. (From Greenspan A: Orthopedic radiology: a practical approach, ed 2, New York, 1992, Gower Medical.) A Fat stripe Muscle B Fig. 43.10 The Pronator Quadratus Fat Pad. (A and B) A narrow fat stripe (arrow) located on the volar surface of the radius is seen on the lat- eral view of the wrist. Although not highly sensitive, volar displacements, anterior bowing, or complete obliteration of this line caused by hema- toma in the setting of trauma is suggestive of wrist injury or fracture. TABLE 43.2 Additional Radiographic Wrist Views Radiographic View Benefit Clenched fist (AP or PA) Exposes scapholunate ligament injury; pushes capitate into proximal carpal row Scaphoid (PA with ulnar deviation) Elongates scaphoid; exposes wrist fractures Carpal tunnel and reverse supinated oblique Identifies fractures involving hamate and pisiform; identifies bony encroachment onto carpal tunnel AP, Anteroposterior; PA, posteroanterior. 507CHAPTER 43 Wrist and Forearm Injuries 1 week. Recent evidence has questioned the practice of immobilizing the wrist in all patients with suspected scaphoid fractures, instead suggesting that the emergent use of advanced imaging modalities is more accurate and cost- effective. The cost of time off work, serial casting, repeat physician evaluation, and office visits was found to exceed that of advanced imaging for definitive diagnosis when these imaging modalities are readily available.8 A recent trial in the United Kingdom demonstrated improved cost savings, diagnostic accuracy, and patient satisfactionassociated with immediate MRI in patients with clinically suspected scaphoid fracture with normal radiographic imaging.9 Importantly, the outcomes of these trials vary depending on MRI cost and accessibility. At this time, we advise thumb spica immobilization with urgent orthopedic follow- up within 1 week for any patient with clinically suspected scaphoid fracture and normal radiographs. The definitive treatment for uncomplicated, nondisplaced distal pole and nondisplaced waist scaphoid fractures depends on various factors, although screw fixation portends a faster recovery time.10,11 There is no current consensus as to whether the thumb should be included in the splint, but clinical trials are ongoing. Most surgeons terminate the thumb spica at the interphalangeal joint line. Some specialists use a long arm (above the elbow) cast or splint, which prevents wrist pronation and supination for the first few weeks, while others prefer short arm immobilization. In addition to flex- ion and extension, pronation and supination may produce fracture displacement in the proximal carpal row. We advise immobilization in a thumb spica short arm splint with urgent follow- up with an orthopedic specialist within 1 week (Fig. 43.12). The duration of total immobilization will vary relative to the location of the frac- ture. More proximal fractures commonly require longer durations to ensure adequate healing. Variability in healing time is related directly to the pattern of blood supply to the scaphoid, which flows from the distal to proximal portion of the bone through the scaphoid tuberosity. This pattern of blood flow also accounts for the higher incidence of AVN and nonunion seen in more proximal fractures (Fig. 43.13). As a result of these complications, scaphoid fractures require urgent orthopedic referral. Lunate fractures Foundations. Fractures of the lunate are relatively uncommon. This injury tends to occur in persons with a congenitally short ulna. Clinical features. Patients will experience pain over the dorsum of the wrist, exacerbated by axial loading of the long finger metacarpal. On physical examination, tenderness may be elicited by palpation over the dorsum of the wrist in the depression felt just distal to Fig. 43.11 Scaphoid Wrist Fracture. A posteroanterior view of the wrist in ulnar deviation (scaphoid view) illustrates a nondisplaced frac- ture of the scaphoid waist (arrow). Fig. 43.12 Short Arm, Thumb Spica Splint. Common immobilization technique used for occult fractures of the scaphoid bone seen in a volar view. Note the optimal 10 degrees of wrist flexion and radial deviation, which assists in scaphoid immobilization. Fig. 43.13 Avascular Necrosis of the Scaphoid Bone. A common complication of scaphoid fractures is avascular necrosis as a result of the distal to proximal osseous blood supply, displacement, or nonunion, resulting in chronic wrist pain and arthritis. 508 PART II Trauma Lister tubercle. The usual mechanism of injury involves a fall on the outstretched hand causing extreme dorsiflexion, with transfer of the resultant force from the capitate to lunate. Complications of lunate fractures include progression to carpal instability, nonunion, and AVN. Kienbock disease, defined by AVN of the lunate, has a predictable pattern of bony collapse, carpal change, and degeneration. It results from a combination of vascular, anatomic, and traumatic mechanisms. In well- established cases of Kienbock disease, the lunate appears sclerotic and fragmented on radiographic examination, and ultimately the bone collapses, with resultant proximal migration of the capitate (Fig. 43.14). These changes cause secondary osteoarthritis of the radiocarpal joint, chronic wrist pain, and weakness at the wrist joint. Initial treatment involves a short arm cast, but patients may require operative intervention. In more severe cases, excision and prosthetic replacement of the lunate or arthrodesis may be necessary. Diagnostic testing. In the ED, wrist radiographs are utilized to assess for lunate fractures; however, fractures of the lunate may be difficult to see on plain films because of overlap of the distal radius, ulna, and other carpal bones. CT or MRI can identify a fracture that is not visible on radiographic imaging. Arthroscopy remains the gold standard for assessing and diagnosing these injuries. Management and disposition. To minimize the risk of AVN, clinically suspected lunate fractures should be immobilized due to the possibility of occult lunate injuries. Nondisplaced lunate fractures are treated with short arm immobilization with double sugar- tong splint or thumb spica splint with orthopedic follow- up in 5 to 7 days. Displaced injuries, open fractures, or those with neurovascular compromise require open reduction and internal fixation (ORIF) and warrant ED orthopedic consultation. Lunate and perilunate dislocations are discussed later, in the section on Carpal Instability. Triquetral Fractures Foundations. There are two main patterns of triquetral fractures that are observed: triquetral body and dorsal cortical chip fractures. An adequate blood supply to the triquetrum reduces the risk of AVN, but does not eliminate it. Clinical features. Patients will experience local tenderness over the dorsal wrist (in the setting of dorsal cortical chips) or volar wrist (avulsion fracture). In addition, swelling and tenderness may be noted over the triquetrum on the ulnar aspect of the wrist. Triquetral body and volar avulsion fractures are commonly associated with perilunate and lunate dislocations, therefore, ligamentous injuries should be considered. Diagnostic testing. A fracture to the triquetral body is best seen on the AP view. Dorsal triquetral chip fractures are best seen on the standard lateral view of the wrist as a small dorsal avulsion fragment, although a more oblique pronated view may be necessary for visualization (Fig. 43.15). CT or MRI can be used to identify a fracture not visible on radiographic imaging, but is generally not indicated in the ED. Management and disposition. Treatment of triquetral fractures involves immobilization in a short arm volar splint. Urgent orthopedic referral within 5 to 7 days is suggested for non- displaced triquetral body fractures. Displaced triquetral body fractures will require ORIF and warrant ED consultation. Dorsal triquetral chips are avulsion- type fractures with a more benign clinical course, requiring routine orthopedic referral within 1 to 2 weeks. Neurovascular compromise and open fracture constitute additional indications for ED consultation. Pisiform Fractures Foundations. The pisiform is unique because it is the only sesamoid- like carpal bone and attaches to the FCU tendon, articulating on its dorsal surface with the triquetrum. Given the important role of forming the lateral wall of Guyon canal, ulnar arterial damage and neurapraxias may be associated with pisiform fractures. Clinical features. Fractures of the pisiform usually occur from a fall on the outstretched hand but also may be seen after direct blows to the hypothenar eminence. This occurs from repetitive trauma when the palm of the hand is used in a hammer- like manner. On physical examination, there is tenderness over the ulnar aspect of the wrist, just distal to the volar crease. Paresthesias in the distribution of the ulnar nerve and hand “clumsiness” (or neurapraxia) from intrinsic muscle dysfunction can occur. Diagnostic testing. Pisiform fractures are poorly seen on routine wrist radiographs and are likely underreported. A reverse (supinated) oblique and carpal tunnel view allow for better visualization (Fig. 43.16). CT scan or MRI can identify fractures that are radiographically occult. Management and disposition. Nondisplaced fractures of the pisiform generally carry a good prognosis and are treated conservatively, with immobilization in a shortarm splint in 30 degrees of wrist flexion with ulnar deviation and orthopedic referral within one week. Most pisiform fractures with evidence of ulnar neurapraxia will resolve, but orthopedic consultation for consideration of surgical decompression is warranted. Pisiform fractures complicated by displacement or nonunion may also require excision and orthopedic consultation in the ED. Hamate Fractures Foundations. The hook or hamulus is the most common site of hamate fracture, although articular surfaces and body fractures are also seen. Clinical features. Fracture of the hook usually occurs from a fall on the outstretched hand or from a direct blow to the palm. A fracture Fig. 43.14 Avascular necrosis of the lunate bone (circle), also known as Kienbock disease. Prevailing theories support fracture of the lunate bone or compromised circulation as the most likely cause of disease. 509CHAPTER 43 Wrist and Forearm Injuries to the hook of the hamate typically occurs in patients participating in racket or club sports (e.g., tennis, golf, baseball). The repetitive use of hammers and vibration equipment (e.g., jack hammers) can predispose workers to hamate fractures and ulnar canal and hypothenar hammer syndrome. Patients may have isolated pain over the hypothenar eminence, decreased grip strength, or compromised distal perfusion. Pain may be localized directly on palpation of the hamate, 1 cm distal and radial to the pisiform. Hamate body and articular surface fractures are usually caused by increased load to the metacarpals of the ring and little fingers. Potential complications of hamate fractures include damage to the ulnar nerve, artery, and vein. Hook of hamate fractures may result in immediate or delayed ulnar arterial or nerve compromise, as well as flexor tendon rupture of the little finger. Diagnostic testing. Hamate body and articular surface fractures are best seen on PA views of the wrist (Fig. 43.17). Standard wrist radiographs have poor sensitivity for hamate hook fractures, which are more readily seen on reverse, supinated oblique, and carpal tunnel views (Fig. 43.18). CT or MRI may be used to identify radiographically occult fractures. CT imaging may be slightly more accurate in identifying hook cortical fractures, but MRI is more accurate in identifying the integrity of the flexor digitorum profundus tendon as well as bone marrow edema and ulnar nerve injuries. Management and disposition. Confirmed hook of hamate fractures should be immobilized in a volar splint that includes the fourth and fifth MCP joints in flexion to prevent tendon shortening. Displaced hook of the hamate fractures are frequently treated with operative resection, but immobilization has been successful for nondisplaced injuries. Vascular compromise, open fractures, or distal ischemia warrants emergent orthopedic consultation; otherwise, splinting and urgent orthopedic follow- up is recommended. Nondisplaced hamate body fractures can be treated with a short arm splint and orthopedic follow- up within one week. Displaced fractures or those associated with rupture of the flexor digiti minimi tendon should be referred to orthopedics urgently, within 3 to 5 days. Fig. 43.15 Triquetral Avulsion Fracture. A minimally displaced trique- tral avulsion or dorsal chip fracture (arrow) is seen on this lateral radio- graph of the wrist. Fig. 43.16 Pisiform Fracture. A reverse supinated oblique radiograph of the wrist profiling the pisotriquetral joint demonstrates minimally dis- placed pisiform fracture (arrow) not typically seen on traditional postero- anterior, lateral, and oblique views. Fig. 43.17 Hamate Fracture. Fracture of the articular surface of the hamate bone (arrow) is seen on this posteroanterior radiograph of the wrist. 510 PART II Trauma Trapezium Fractures Foundations. There are two main types of trapezium fractures, those involving the body and trapezial ridge. Clinical features. A direct blow to the adducted thumb causes fracture through the body of the trapezium, with transmittal of the force by the base of the thumb metacarpal. Avulsion fractures of the trapezial ridge occur with forceful radial deviation or rotation of the wrist. On examination, patients report pain with movement of the thumb and on direct palpation of the trapezium, just distal to the scaphoid in the anatomic snuffbox. Complications of distal trapezium ridge fractures include nonunion, median nerve irritation, CMC arthritis, carpal tunnel syndrome, flexor carpi radialis tendinopathy, and loss of pinch strength. Diagnostic testing. Although trapezium fractures may be seen on the AP view of the wrist, they are typically better visualized on oblique views (Fig. 43.19), a Bett view, and a carpal tunnel view to evaluate for ridge fractures. Trapezium fractures can be radiographically occult. CT scanning or MRI can be used to identify fractures that are not evident on X- ray. Management and disposition. Nondisplaced trapezium fractures are treated with immobilization in a short arm thumb spica splint, with orthopedic referral within one week. Displaced fractures, comminuted fractures, intra- articular fractures, distal ridge fractures, and involvement of the carpometacarpal joint warrant urgent orthopedic consultation for ORIF within 2 to 3 days. Neurovascular compromise or open fractures warrant emergent consultation. Capitate Fractures Foundations. The capitate lies in a central position in the distal carpal row and, because of this protected location, it is rarely fractured. Clinical features. The mechanism generally is a direct blow to the dorsum of the wrist. Fractures may also be seen in association with perilunate dislocations after a fall on the outstretched dorsiflexed hand. Clinical examination reveals dorsal wrist pain and swelling, with localized tenderness over the capitate. Complications of nonunion and AVN of the proximal fragment are rare but do occur because the capitate receives blood supply through its distal half. Diagnostic testing. Fractures usually are visible on the standard PA view of the wrist, although the lateral and oblique views may be helpful in determining the presence of rotation or displacement of the fracture fragment. CT scan or MRI can be useful in identifying radiographically occult fractures. Management and disposition. Identified or suspected nondisplaced fractures of the capitate should be managed with immobilization in a short arm thumb spica splint with routine orthopedic referral within one week. Urgent orthopedic referral within 2 to 3 days is recommended for fractures with displacement. ED consultation is indicated for associated carpal dislocation, open fractures, or neurovascular compromise. Trapezoid Fractures Foundations. Trapezoid fractures are rare, usually seen in association with other carpal injuries. Clinical features. The typical mechanism of injury is a direct blow down the long axis of the index metacarpal, which may result in isolated fracture to the trapezoid or cause a dorsal fracture- dislocation. On clinical examination, pain and tenderness are localized over the dorsum of the wrist at the base of the second metacarpal. Diagnostic testing. The fracture may be visible on routine PA views of the wrist; however, oblique views may be superior for visualization of the injury. CT scan or MRI can be used in identifying radiographically occult fractures. Management and disposition. Confirmed or suspected nondisplaced trapezoid fractures should be immobilized with a short arm thumb spica splint with urgent orthopedic referral in 2 to 3 days. Displaced fractures or fracture dislocations warrant orthopedic consultation in the ED for reduction and fixation. Trapezoid fractures have a high rate of nonunion and AVN. Fig. 43.18 Carpal Tunnel View of Wrist. The pisiform bone (white arrow) and hook of hamate or hamulus (black arrow) are better visual- ized on carpal tunnelviews of the wrist when hypothenar palmar wrist pain is present, and a fracture is suspected. Fig. 43.19 Trapezium Fracture. An oblique view of the wrist shows an isolated, comminuted, intraarticular fracture of the trapezium body (arrow). 511CHAPTER 43 Wrist and Forearm Injuries Carpal Instability Foundations. The Mayfield classification of carpal instability is comprised of four distinct stages. Each stage represents a sequential intercarpal injury, beginning with scapholunate joint disruption and proceeding around the lunate, creating progressive carpal instability (Fig. 43.20). Each stage also may be associated with specific bony fractures, which, if present, should alert the emergency clinician to the possibility of an occult perilunate ligamentous injury. These associated injury patterns include fractures of the radial styloid, scaphoid, capitate, and triquetrum. Clinical features. Carpal ligamentous injury is caused by wrist hyperextension, ulnar deviation, and intercarpal supination. Patients with these carpal dislocation injuries typically have a history of a fall on the outstretched hand. They complain of pain and swelling over the dorsum of the wrist, with limited range of motion. On physical examination, tenderness to palpation is noted over the dorsum of the wrist. Delayed scapholunate instability may be clinically elicited by a provocative maneuver, such as the Watson scaphoid shift test, which will increase pain and produce a clunk or snap. The test is performed by placing upward pressure on the scaphoid tuberosity while the hand is in ulnar deviation. In scapholunate instability, this action will cause the scaphoid to ride out of the radial fossa over the dorsal rim and, as the hand is moved back radially, a painful snap is produced. In the setting of acute trauma, this test is often too painful to perform. With perilunate and lunate dislocations, visible deformity of the wrist also is apparent, and two- point sensation in the median nerve distribution often is diminished. Complications of carpal dislocation injuries include median nerve injury and chronic carpal instability, with resultant degenerative arthritis. Diagnostic testing. A stage I injury, or scapholunate dissociation, results in a characteristic widening of the scapholunate joint on the PA view, which has been called the Terry Thomas sign after the British comedian with a gap between his front teeth. This radiographic sign has been updated to reference more current celebrity figures and is also referred to as the David Letterman sign. This injury pattern may be associated with a rotary subluxation of the scaphoid. Radiographically, the scaphoid is seen end- on, with the cortex of the distal pole appearing as a ring shadow, referred to as the signet ring sign (Fig. 43.21). Scapholunate dissociation may not be demonstrated on routine radiographs, so when there is clinical suspicion for this injury, additional stress views could be considered. Radiographs taken with a clenched fist and with ulnar deviation (the clenched fist AP view) accentuate widening of the scapholunate joint and are suggestive of disease when a gap larger than 3 mm is measured. A stage II injury, or perilunate dislocation, is seen best on the lateral view of the wrist. Although the lunate remains articulated to the distal radius, the capitate is dorsally dislocated. The PA view shows overlap of the distal and proximal carpal rows and also may show an associated scaphoid, radial styloid, or capitate fracture (Fig. 43.22). A stage III injury appears identical to a stage II injury but includes a dislocation of the triquetrum that is seen best on the PA view, with overlap of the triquetrum on the lunate or hamate. This injury may be associated with a volar triquetral fracture. A stage IV injury, or lunate dislocation, results in a characteristic triangular appearance of the lunate on the PA view caused by the rota- tion of the lunate in a volar direction. This triangular appearance is commonly referred to as the piece of pie sign. This rotation also is visible on the lateral view of the wrist, in which the lunate looks like a cup tipped forward and spilling its contents, referred to as the spilled tea- cup sign. On the lateral view, the capitate is seen to lie posterior to the lunate and often has migrated proximally to contact the distal radius (Fig. 43.23). MRI can identify these injuries in the setting of negative radiographs but is rarely indicated in the ED. Arthroscopy remains the gold standard for definitive diagnosis. Management and disposition. Carpal dislocation injuries need emergent orthopedic consultation in the ED for reduction and stabilization. ED management of dissociations without evidence of dislocation or neurovascular injury consists of immobilization and urgent orthopedic follow up within one week. II IIII IV Fig. 43.20 Sequential stages of carpal dislocation. Each of four stages (I–IV) represents a sequential intercarpal ligament injury proceeding around the lunate. (From Greenspan A. Orthopedic radiology: a practical approach. 2nd ed. New York: Gower Medical; 1992.) Fig. 43.21 Scapholunate Dissociation With Scaphoid Subluxation. Posteroanterior view of the wrist shows characteristic widening of the scapholunate joint (black arrow), known as the Terry Thomas sign, and a ring shadow over the scaphoid (white arrow) secondary to subluxation, known as the signet ring sign. 512 PART II Trauma A B Fig. 43.23 Lunate Dislocation. (A). This posteroanterior view shows the characteristic triangular shape of the lunate bone during dislocation. (B) Volar displacement of the lunate resembles a spilled teacup on the lat- eral view. Note the disrupted articulation between the lunate and distal radius and realignment of the radius, capitate, and metacarpals, suggesting lunate dislocation. A B Fig. 43.22 Perilunate Dislocation. (A) This posteroanterior view of the wrist shows an abnormal- appearing lunate bone, obvious disruption of the normal carpal arcs, and commonly associated and, in this case, dis- placed scaphoid fracture. (B). Lateral view shows a dislocated and dorsally displaced capitate bone in relation to the lunate. Of note, the lunate maintains its articular connection and alignment with the radius, suggesting a perilunate dislocation. 513CHAPTER 43 Wrist and Forearm Injuries Radiocarpal Dislocation Foundations. Radiocarpal dislocations and fracture dislocations are considered extremely rare and are typically associated with high- energy trauma. Clinical features. Patients are commonly involved in polytrauma scenarios. Dislocations may be volar or dorsal, although ulnar translation of the carpal bones is much more common than radial translation. Diagnostic testing. Radiographs of the wrist are typically sufficient to identify radiocarpal dislocations. Management and disposition. Emergent reduction of these injuries is paramount because of the extensive soft tissue damage and commonly associated neurovascular compromise. Reductions may be difficult to maintain in these complex and unstable injuries, which usually require ORIF. Emergent orthopedic consultation in the ED is indicated. Distal Radius and Ulna Injuries Distal radius and ulna fractures typically occur from a ground- level fall on the outstretched hand in older patients and from high- energy trauma in younger patients. These injuries are commonly closed and may have intraarticular involvement and displacement. They frequently require ED closed reduction, splinting, and orthopedic referral. Plain radio- graphs are generally adequate for the diagnosis and management of these injuries; rarely is advanced imaging indicated in the ED. A neurovascu- lar examination should be performed to exclude any median, radial, or ulnar neurapraxia and radial or ulnar arterial compromise caused by the deformity or fracture fragments. Post- reduction radiography and a neu-rologic examination are also recommended. Open fractures, instability, or an acute carpal tunnel syndrome (ACTS) are indications for emergent orthopedic evaluation. Vascular compromise should prompt immediate reduction in conjunction with orthopedic consultation. Patients with open fractures should receive tetanus immunization prophylaxis and tetanus immune globulin (if unvaccinated), and 2 g of cefazolin intrave- nously, prior to surgical intervention. Numerous classification patterns have been devised, and the most commonly encountered fractures are discussed in the following sections. Colles Fracture Foundations. A Colles fracture refers to a transverse fracture of the distal radial metaphysis, which is dorsally displaced and angulated. Clinical features. Patients classically present with a “dinner fork deformity” on physical examination. The fracture usually is located within 2 cm of the radial articular surface and may be associated with comminution and intraarticular extension into the radiocarpal or radioulnar joints. Carpal instability may also occur. Complications of Colles fractures are seen most often in older patients and those with comminution, displacement, and inadequate fracture reduction. Although radial and ulnar nerves may be compromised, median nerve injury is most common and may occur acutely from contusion, traction from displacement, transection from fracture fragments, nerve compression after closed reduction, overlying cast pressure, or secondary to ACTS. Thus, it is important to evaluate neurologic function before and after fracture reduction and splint application. Diagnostic testing. The PA view may show extension of the fracture into the radioulnar or radiocarpal joints and the amount of intraarticular step- off and radial shortening present. The degree of dorsal displacement and angulation is best seen on the lateral view, with loss of the normal volar tilt of the distal radial articular surface (Fig. 43.24). Management and disposition. Most Colles fractures require ED reduction for restoration of radial length, correction of dorsal angulation (especially when greater than 20 degrees), restoration of A B Fig. 43.24 Colles Fracture. (A) Posteroanterior view shows fracture and shortening of the radius, intraartic- ular extension, and associated ulnar styloid fracture. (B) Lateral view shows typical dorsal displacement and angulation of the radial fracture known as the dinner fork deformity. 514 PART II Trauma anatomic volar tilt. Closed reductions should be performed under procedural sedation, local or regional anesthesia, or a combination of these options followed by immobilization in a double sugar tong splint. Splinting should immobilize the wrist but allow for finger movement. Immediate circumferential casting, as well as overly tight splinting, should be avoided for at least 24 hours because edema from this injury may induce subsequent pain or neurovascular compromise. Successful reduction allows for urgent outpatient orthopedic referral within 2 to 3 days in most cases. Methods of local and regional anesthesia for distal radius frac- ture reduction include the classic hematoma block, IV regional anes- thesia, known as the Bier block, and regional nerve blocks, including median, radial, ulnar, and brachial plexus approaches. The hematoma block remains an easy and effective method of anesthesia and may be performed by placing a 22- gauge needle in the dorsum of the distal radius, withdrawing until a fracture hematoma is encountered and then instilling 5 to 10 mL of 1% or 2% lidocaine, with or without the addition of a longer- acting agent such as bupivacaine (Fig. 43.25).12 Hematoma blocks may avoid the requirement for procedural sedation and decrease ED length of stay. For pediatric distal radial fractures, local anesthesia should not be injected into the growth plate but is otherwise acceptable. Use of finger traps is another effective means of obtaining reduction to allow positioning for splinting (Fig. 43.26). The more comminuted and displaced the fracture, the higher the likelihood that operative reduction will be necessary. Indications for emergent Colles fracture reductions include any neurovascular compromise, significant deformity, soft tissue tension, tenting of the skin, and loss of volar tilt, with significant dorsal angu- lation (>20 degrees). Loss of reduction will occur in many of these patients before orthopedic follow- up, especially intra- articular frac- tures, and in older adults, for whom the long- term benefits of anatomic restoration appear less beneficial. The American Academy of Ortho- pedic Surgeons has suggested surgical fixation of fractures with more than 3 mm of shortening, 10 degrees of dorsal tilt, and intra- articular step- off of more than 2 mm post- reduction. ED orthopedic consulta- tion is recommended if a reduction is unable to be maintained, or if there is evidence of open fracture, severe comminution, neurovascular compromise, compartment syndrome, or skin tenting. Smith Fracture Foundations. Smith fracture is a transverse fracture of the metaphysis of the distal radius, with associated volar displacement and angulation. The fracture may extend into the radiocarpal joint. Clinical features. The typical mechanism of injury involves a direct blow to the dorsum of the wrist or a fall onto the dorsum of the hand resulting in extreme palmar flexion. This fracture also may be seen after a backward fall on an outstretched hand, with the forearm in supination. The patient has a swollen painful wrist, which is deformed, with fullness visible on the volar aspect. On physical examination, a “garden spade deformity” will classically be observed. Because the displacement is opposite to that seen with a Colles fracture, Smith fractures are often called a “reverse Colles fracture.” Diagnostic testing. The fracture is visible on PA and lateral radiographs of the wrist, but the lateral view best shows the degree of volar displacement and angulation (Fig. 43.27). Management and disposition. Treatment of this fracture involves closed reduction and immobilization in a splint if the fracture is extra- articular, as discussed for Colles fracture. Unlike Colles fracture, however, Smith fracture is more likely to be unstable and to require operative repair; it also has an increased tendency to cause neurovascular compromise, specifically median nerve compression. Urgent orthopedic referral within 2 to 3 days or emergent consultation is indicated based on the severity of angulation, neurovascular compromise, or associated soft tissue complications. Delayed tendon complications, including EPL entrapment and rupture, have been documented. Prognosis is most favorable in patients with successful reduction and restoration of the normal radial length and volar tilt. ED consultation is warranted for similar indications to the Colles fracture. Barton Fracture Foundations. Barton fracture is an oblique intraarticular fracture of the rim of the distal radius, with displacement and dislocation of the radiocarpal joint along with the fracture fragment.13 The fracture may involve the dorsal rim of the radius with dorsal carpal subluxation (classic Barton fracture) or may involve the volar rim with volar carpal Fig. 43.25 Hematoma Block. Sterile preparation of the fracture area is performed, and local anesthetic is then introduced to the hema- toma that surrounds the fracture site to assist with pain control during reduction. Fig. 43.26 Finger Traps. The distal radius reduction method typically involves traction followed by manipulation facilitated by the finger traps. Ten pounds of weight are hung from the elbow at 90 degrees of flexion for approximately 10 minutes before the reduction attempt. 515CHAPTER 43 Wrist and Forearm Injuries subluxation (volar Barton fracture). While these fractures are rare, the volar- anterior margin fracture isseen more often than the dorsal- posterior margin fracture. Clinical features The mechanism of injury for these fractures is a high- velocity impact across the articular surface of the radiocarpal joint, with the wrist in volar flexion (causing a volar rim fracture) or dorsiflexion (causing a dorsal rim fracture). Complications include posttraumatic arthritis of the radiocarpal joint and delayed carpal instability. Both complications are seen more commonly when reduction fails to achieve or maintain anatomic realignment of the radiocarpal joint surface. Diagnostic testing. Volar and dorsal rim fractures are visible on PA and lateral wrist radiographs; however, the lateral view best shows the degree of articular surface involvement and amount of associated fracture displacement (Fig. 43.28). Management and disposition. Treatment of these unstable fractures requires emergent orthopedic consultation for reduction and fixation. Closed reduction may be successful when performed under fluoroscopy, although most fractures require percutaneous pinning or ORIF to restore the articular surface of the radius and stabilize the carpus. Hutchinson Fracture Foundations. Hutchinson fracture, or chauffeur’s fracture, is an intra- articular fracture of the radial styloid. Clinical features. The mechanism of injury is usually a direct blow or fall resulting in trauma to the radial side of the wrist. The term chauffeur’s fracture originated in the era of hand- cranked automobiles, when this injury occurred because of direct trauma to the radial side of the wrist from the recoil of the motor crank. Posttraumatic arthritis is a common complication of radial styloid fractures and more common with displacement and scapholunate ligament disruption. Diagnostic testing. The fracture is seen best on the PA view of the wrist as a transverse fracture of the radial metaphysis, with extension through the radial styloid into the radiocarpal joint. Management and disposition. Nondisplaced fractures may be immobilized in a sugar tong splint, with the patient given urgent orthopedic referral within 2 to 3 days. Displaced fractures, which are frequently associated with scapholunate ligament disruption, require emergent open or closed reduction and fixation (Fig. 43.29). Because the radial styloid is the primary site of attachment for many of the ligaments of the wrist, accurate fracture reduction and union are crucial for proper wrist function. Distal Radioulnar Joint Disruption Foundations. Acute dislocation of the DRUJ can occur as an isolated injury, which is rare, or in association with a fracture to the distal radius (Colles fracture), radial diaphysis (Galeazzi fracture), or radial head (Essex- Lopresti injury). Clinical features. Certain characteristic findings on clinical examination may constitute the only clue to the presence of this injury. The typical mechanism of injury is a fall on the outstretched hand with hyperpronation, resulting in dorsal dislocation, or hypersupination, causing volar dislocation of the ulna. Dorsal ulna dislocations are more common than volar dislocations. Another mechanism known to cause DRUJ dislocation is the catching of the hand in rotating machinery, resulting in the same forcible hyperpronation or supination. This forcible rotation of the wrist causes disruption of the TFCC, the major stabilizer of the DRUJ, and may result in an associated avulsion fracture of the ulnar styloid. Patients with this injury have a history of sudden onset of pain with a snapping sensation in the wrist, swelling, and limited range of A B Fig. 43.27 Smith Fracture. (A) Posteroanterior view shows a metaphy- seal fracture of the radius, with shortening and associated ulnar styloid base fracture. (B) Lateral view shows volar displacement of the distal fracture fragment along with the carpus. Fig. 43.28 Volar Barton Fracture. Lateral radiograph of the wrist shows typical oblique intraarticular fracture of the volar rim of the radius, with associated displacement of the distal radial fragment and carpus dislocation. 516 PART II Trauma motion. On examination, tenderness is present over the ulnar aspect of the wrist, with palpable crepitus on supination and pronation. On examination, the piano key test may be used to assess for DRUJ insta- bility. The test is positive when the ulnar head springs back like a piano key after being depressed volarly and then released. The ballottement test also evaluates stability of the DRUJ. With this test, the radius is grasped firmly by the examiner while the ulna is fixed between the examiner’s other thumb and index finger. Pressure is then applied to the ulna in dorsal and volar directions with respect to the radius. Increased displacement relative to the contralateral wrist suggests instability. With a dorsal dislocation of the ulna, the ulnar styloid appears more prominent than on the unaffected side, and significant pain and lim- itation of movement are noted on supination of the wrist. With a volar dislocation of the ulna, there is loss of the normal ulnar styloid prom- inence, with pain and limitation of movement on pronation. These characteristic clinical findings should alert the emergency clinician to the possibility of DRUJ disruption and prompt the appropriate imaging studies to confirm the presence or absence of injury. Diagnostic testing. Diagnosis often is difficult because when the injury occurs in isolation or is not suspected, plain radiographs commonly are reported as normal. Well- positioned lateral radiographs of the wrist may show the presence of a DRUJ dislocation with more than 20 degrees of dorsal angulation or volar displacement, but pain and inability of the patient to rotate the wrist fully may cause a false- negative result because a true lateral view cannot be obtained. Fractures of the ulnar styloid base increase suspicion for a DRUJ disruption. It also is important to assess for radial head fractures because this injury is commonly associated with DRUJ disruption and interosseous membrane rupture (see below, “Essex- Lopresti Lesion”). A DRUJ dislocation may be seen on the PA view of the wrist radiograph showing significant overlap or widening of the distal radius and ulna (Fig. 43.30). If there is significant clinical suspicion of injury, and the radiographic appearance is normal, a CT scan or MRI may assist in the diagnosis. Management and disposition. Treatment of DRUJ dislocations commonly requires emergent orthopedic consultation for reduction and stabilization. Closed reduction with the forearm in supination followed by application of a long arm splint is indicated. Alternatively, open reduction is often necessary with volar dislocations because the ulnar head may be locked on the distal radius. Operative reduction is also necessary in dorsal dislocations to repair the associated injury to the TFCC. Any associated bony injuries should be managed with immobilization as indicated. SOFT TISSUE INJURIES OF THE WRIST Carpal Tunnel and Acute Carpal Tunnel Syndrome Foundations Carpal tunnel syndrome (CTS) is the most common entrapment neu- ropathy; it occurs at the wrist and results in compression of the median nerve. CTS is typically a chronic, progressive, repetitive overuse syn- drome with a female preponderance. The transverse carpal ligament and volar surfaces of the carpal bones form the carpal tunnel. It is a rigid compartment that contains nine flexor tendons (flexor pollicis longus, four flexor digitorum superficialis, and four flexor digitorum profundus tendons) and the median nerve. Clinical Features The classic symptoms include a gradual onset of numbness, paresthe- sia, and pain in the median nerve distribution (thumb, index, long and radial aspect of the ring finger; see Table 43.1). These symptoms often are bilateral and are worse during the night and after strenuous activ- ities. Typically, patients report numbness and paresthesiason awak- ening that lessens when the hands are shaken or held in a dependent Fig. 43.29 Hutchinson Fracture. Posteroanterior radiographic view shows intraarticular fracture of the radial styloid with displacement and scapholunate dissociation, a common complication of untreated Hutchinson fracture. Fig. 43.30 Distal Radioulnar Joint Dislocation. Posteroanterior radio- graphic view shows an ulnar styloid base fracture suggestive of trian- gular fibrocartilage complex disruption and widening of the radius and ulna, consistent with distal radioulnar dislocation. 517CHAPTER 43 Wrist and Forearm Injuries position. Pain may actually radiate proximal to the carpal tunnel, and symptoms may progress to include decreased grip strength, hand clumsiness, thenar atrophy, and trophic ulceration of the fingertips. Differential Diagnoses CTS can be associated with numerous systemic conditions, such as rheumatoid arthritis, hypothyroidism, diabetes mellitus, renal failure, congestive heart failure, acromegaly, and collagen vascular diseases. Each of these systemic diseases is thought to produce an increase in pressure within the carpal tunnel from thickening of the flexor syno- via or transverse carpal ligament. Hormonal changes associated with pregnancy and menopause also are known to be associated with CTS. Differential diagnoses also include cervical radiculopathy (especially the C6 or C7 nerve root) and Raynaud syndrome. The median nerve may also be compressed at other sites including the pronator teres. A brachial plexopathy may also produce similar symptoms. Diagnostic Testing The most common provocative test supporting the diagnosis of CTS is the wrist flexion or Phalen test (Fig. 43.31). This test is performed by asking the patient to flex the wrists fully for 60 seconds while holding the forearms in a vertical position. The test result is positive if paresthe- sia or numbness develops in the median nerve distribution. Other tests suggesting CTS are weakness observed on thumb abduction testing and Tinel sign, which demonstrates pain or paresthesias elicited by light tapping over the median nerve at the wrist. Durkan test, or the median nerve compression test, consists of the application of pressure directly over the median nerve at the carpal tunnel and may have the highest sensitivity and specificity for disease. However, no physical examina- tion maneuver is completely reliable in making the diagnosis and is therefore more supportive when used in combination. Nerve conduc- tion studies have traditionally been used to confirm the diagnosis. MRI and ultrasound are also being used for confirmation, but emergently the diagnosis of CTS is primarily clinical. Management and Disposition Conservative (nonoperative) treatment for CTS yields variable results. Specific measures include splinting the wrist in a neutral position and administering cortisone injections in the carpal tun- nel as an outpatient in an orthopedic clinic. Splinting initially may be prescribed full time and then reduced to immobilization at night only. Five factors that lessen the likelihood of successful nonoper- ative treatment are (1) age older than 50 years, (2) symptom dura- tion longer than 10 months, (3) constant paresthesias, (4) stenosing flexor tenosynovitis, and (5) positive Phalen test result at less than 30 seconds. Nonsteroidal antiinflammatory drugs (NSAIDs) have proved to be of little benefit. Open or endoscopic surgical release of the flexor retinaculum to unroof the carpal tunnel is indicated when medical management fails. ACTS, which occurs over hours rather than weeks or months, is much less common than the chronic, gradually progressive presenta- tions of CTS. ACTS is more often directly related to fractures, fracture- dislocations, hemorrhagic conditions, infections, vascular disorders, and edema involving the wrist. Although the carpal tunnel is open at both ends, it has the physiologic properties of a closed compartment. Distal radius fractures are the most common cause of ACTS; however, lunate and perilunate dislocations are associated, and even isolated carpal fractures and rupture of the EPL tendon have been found to be associated with ACTS as well. Trauma resulting in an ACTS is typically relieved by closed reduction, and no reliable clinical method currently exists for differentiating acute median nerve compression in ACTS from concussive insult. In the absence of trauma, ACTS has occurred secondary to hemorrhagic, vascular, and bleeding disorders, and anti- coagulant use. When ACTS has been diagnosed, ED orthopedic con- sultation is recommended for surgical decompression and release of the transverse carpal ligament. De Quervain Disease Foundations De Quervain disease and intersection syndrome, like CTS, have been grouped into the overuse or repetitive strain injury pattern category, sometimes referred to as work- related cumulative trauma. The APL and EPB, both within the first dorsal extensor compartment of the wrist, are the tendons affected in de Quervain disease. Traditionally known as a stenosing tenosynovitis or tendinitis, de Quervain disease involves enlarged tendons, which may reach five times their original size, creating a stenosing tendinopathy. Clinical Features Clinically, patients report pain on the radial side of the wrist, with ulnar deviation, thumb movements, weakened grip strength, or a com- bination of these symptoms. Onset is gradual and typically the result of increased use. De Quervain disease is thought to be common, affecting women six times more frequently than men, typically at an age older than 40 years. Diagnostic Testing Radiographs are useful in ruling out bony pathology, but the diagno- sis may be made with physical examination alone. Finkelstein test and radial styloid tenderness have long been considered to be a pathogno- monic signs of de Quervain disease. Ultrasound reveals fluid in the first dorsal extensor tendon compartment tendon sheath with associated thickening of the APL and EPB tendons. Management and Disposition Conservative interventions of rest, splinting, and NSAIDs are the first- line treatments for mild to moderate disease. Thumb spica splints effectively immobilize the APL and EPB, but pain may return when the inciting activities are resumed. ED management should consist of rest, thumb spica splint immobilization, and nonsteroidal antiinflamma- tory agents. Orthopedic consultation is warranted within a few weeks. Injection of corticosteroid preparations into the dorsal extensor com- partment of the wrist may be offered at follow- up with an orthopedic physician within 3 to 5 weeks. Patients with refractory or severe cases that interfere with activities of daily living may undergo surgical release of the first dorsal extensor compartment of the wrist, with decompres- sion of the APL and EPB tendons.Fig. 43.31 Phalen Test. 518 PART II Trauma Intersection Syndrome Foundations Intersection syndrome is another overuse tendinopathy that clinically manifests with pain on the radial side of the wrist, approximately 4 to 8 cm proximal to the site of de Quervain disease. Pathophysiologically, intersection syndrome occurs secondary to inflammation where the muscle bellies of the APL and EPB cross over the muscle bellies of the extensor carpi radialis longus and brevis, proximal to the retinaculum. Clinical Features The condition is also known as crossover or oarsman syndrome. The mechanism of injury is secondary to rowing, weightlifting, or a repeti- tive resistance pulling action. Diagnostic Testing Physical examination findings include significant pain, soft tissue swelling, and crepitus with movement in more severe cases. Ultra- sound findings may include thickened tendons or effusion, and radio- graphs are generally negative for pathology. Management and Disposition The treatment for this disease is immobilization with a wrist splint and antiinflammatory medications.Although surgical treatments have been described, this syndrome is typically self- limited. Orthopedic fol- low- up is recommended within 3 to 5 weeks. FOREARM FOUNDATIONS Forearm injuries are common encounters in the ED. There is a bimodal age distribution of patients who suffer forearm injuries—children aged 6 to 15 years and adults older than 50 years.14 In children, forearm fractures account for nearly 50% of all pediatric fractures and are on the rise due to an increase in sporting activities and body mass index (BMI). Refer to pediatric fractures referenced in Chapter 160. Anatomy, Physiology, and Pathophysiology Mechanisms of injury for forearm fractures include falls on out- stretched hands, direct blows to the area, or high- energy trauma, such as involvement in a motor vehicle collision. Evaluation of forearm inju- ries requires an understanding of the interdependent biomechanical relationship between the radius and ulna. These two bones articulate at the proximal and distal ends, which allows the radius to rotate around the ulna to provide pronation and supination. Because fractures of the radius or ulna can result in dislocation at the wrist or elbow, emer- gency clinicians should be vigilant when treating forearm fractures. Early diagnosis and prompt treatment of these injuries are critical to prevent loss of function. The forearm is a unique two- bone structure with the radius and ulna being bound at both ends by a ligamento- capsular structure. The proximal radioulnar joint (PRUJ) consists of an articulation between the radial head and ulna. The radial head, the primary stabilizer of the forearm, combined with the annular, quadrate, radial, and ulnar liga- ments, provides strong support at the PRUJ. At the DRUJ, the TFCC and anterior and posterior radioulnar ligaments support the articula- tion of the distal radius and ulna. The interosseous membrane further stabilizes the forearm by providing a strong interconnection between the radius and ulna. The ulna is relatively straight and provides the rotational axis for the bowed radius to rotate around through various planes of motion. The supinator, pronator teres, and pronator quadratus muscles insert along the shaft of the radius and ulna to provide their named function, but they also are responsible for the deforming forces in forearm fractures. The forearm is typically divided into three compartments—volar, dorsal, and mobile wad of Henry. The interosseous membrane divides the volar and the dorsal compartments, and the mobile wad is located laterally (Fig. 43.32). The volar compartment, which can be further divided into superficial and deep layers, contains the pronators and flexor muscles of the hands. The radial, ulnar, and anterior interosseus arteries and median, ulnar, and superficial radial nerves are also con- tained within the volar compartment. The dorsal compartment con- sists of the extensor muscles of the hand and posterior interosseous artery and nerve. The mobile wad is located in the proximal lateral aspect of the forearm and contains the brachioradialis, extensor carpi radialis longus, and extensor carpi radialis brevis. CLINICAL FEATURES Obtaining the mechanism of injury is important in the initial assess- ment of a forearm injury. The most common mechanism of injury is an axial load applied to the forearm through the hand, which often leads to rotational displacement. Patients may present with obvious defor- mity and a significant amount of pain. Physical examination of the forearm injury begins with visual inspection by evaluating for swelling along the injured area, obvious deformity, and evidence of lacerations. Gentle palpation can assist in localization of the injury, reveal crepitus in grossly unstable fractures, and allow assessment of skin turgor in the evaluation of compartment pressure. Significant swelling, as well as disproportionate pain, pares- thesia, and paleness of skin, should alert emergency clinicians to the potential development of compartment syndrome. Neurologic evalua- tion should include careful examination of motor and sensory function of the radial, ulnar, and median nerves. Assessment of the brachial, radial, and ulnar arteries should be performed. See pediatric trauma and compartment syndromes referenced in Chapter 160. DIFFERENTIAL DIAGNOSES When approaching a patient with forearm pain, differential diagnoses will be determined by the mechanism of injury, location of pain, and chronicity of the symptoms. Acute trauma associated with inability to supinate will raise suspicion for acute fracture involving radius or ulna depending on the location. Other differential diagnoses include straining of the forearm muscles and tear of the ligaments stabilizing radius and ulna. For patients with chronic forearm pain without acute trauma, repetitive strain injury due to overuse and repetitive movement should be considered. DIAGNOSTIC TESTING: RADIOLOGY The radiologic evaluation of the forearm injury should begin with the AP and lateral views. It is necessary to include wrist and elbow in the x- ray examination of the forearm to exclude any concomitant injuries to the DRUJ or PRUJ. On the normal AP view of the forearm, a medially pointing radial styloid and laterally projecting biceps tuberosity of the proximal radius are visible. On the lateral view, the coronoid process of the proximal ulna points volarly, and the ulnar styloid lies dorsally (Fig. 43.33). Any deviation suggests an abnormal rotational or axial deformity. The nor- mal radiologic findings of the forearm, including radiocarpal articula- tion angle, relationship between radial styloid and ulnar styloid, and normal volar tilt of the radius, are described earlier in the Radiology of the Wrist section of this chapter. 519CHAPTER 43 Wrist and Forearm Injuries Injury to the radial head can be evaluated by drawing a midaxis line through the radial shaft, neck, and head. This radial midaxis line should intersect the center of capitellum of the elbow on any radiologic view. Any variance from this alignment should raise suspicion regard- ing radial head dislocation (Fig. 43.34). CT scans can be useful when there is a suspicion of extension of the fracture into the DRUJ or PRUJ on plain radiography. MRI is the study of choice for evaluation of soft tissues (e.g., muscle, tendon, ligament) of the forearm, including the interosseous membrane. Ultrasound can also help with evaluation of interosseous membrane injury and to determine when pediatric forearm fractures have been adequately realigned after closed reduction.15 Shaft Fractures of Radius and Ulna Foundations Fractures involving both the radius and ulna, also known as both bone fractures, are common forearm injuries. Clinical Features Patients often have pain and obvious deformity of the forearm as a result of blunt trauma. Physical examination includes assessing for any associated neurovascular injury or open fracture. Compartment syndrome should be considered in all patients with these types of injury. Common complications of combined radius and ulna fractures are nonunion, malunion, infection, and neurovascular injury. Diagnostic Testing The initial radiologic evaluation should include the AP and lateral radiographs of the forearm, as well as dedicated wrist and elbow radiographs. Management and Disposition After initial evaluation, any open fractures should be irrigated with sterile water or saline to decrease contamination, and a sterile dressing should be applied, along with parenteral antibiotics, while awaiting emergent operative management. Any grossly displaced fracture- dislocation should be reduced to improve alignment and prevent impending or ongoing neurovascular injury. Application of a sugar tong forearm splint should be made with an urgent referral within 7 days to an orthopedist, as long as there is no evidence of open fracture or neurovascular compromise. Nondisplacedconcurrent radius and ulna fractures are uncommon and most both bone fractures of the forearm in adults generally require operative management as soon as possible to achieve the alignment. Ulnar artery and nerve Median nerve AIA and AIN Radial artery and nerve Radius ECR ECU EDM EDC APL EPL FDP FDS FCR FPL PL BR FCU PIA and PIN ULNA Comparments: Interosseous membrane Volar Mobile Dorsal Fig. 43.32 Cross Section of the Forearm Demonstrating the Compartments and Neurovascular Struc- tures. The volar compartment contains the flexors of hand and wrist, including the palmaris longus (PL), flexor digitorum superficialis (FDS), flexor carpi radialis (FCR), flexor pollicis longus (FPL), flexor digitorum profundus (FDP), and flexor carpi ulnaris (FCU), as well as the ulnar nerve, ulnar artery, median nerve, radial artery, super- ficial branch of the radial nerve, anterior interosseous artery (AIA), and anterior interosseous nerve (AIN). The dorsal and volar compartments are bordered by the interosseous membrane. The dorsal compartment con- tains finger extensors and long thumb abductor, as well as the posterior interosseous artery (PIA), posterior interosseous nerve (PIN), abductor pollicis longus (APL), extensor digiti minimi (EDM), extensor carpi ulnaris (ECU), extensor pollicis longus (EPL), and extensor digitorum communis (EDC). The mobile wad, which is often considered to be a third compartment, is composed of the extensor carpi radialis brevis and longus muscles (ECR) and brachioradialis (BR). (Courtesy Dr. S. Johnson.) 520 PART II Trauma Ulna Shaft Fractures Foundations Isolated fractures of the ulna shaft, known as nightstick fractures, are seen frequently in the ED. Clinical Features Patients often have pain and swelling over the medial aspect of the forearm, because the usual mechanism involves raising the arm over- head to protect it from a direct traumatic impact. Careful inspection of the skin is necessary as many patients have open fractures, given the superficial position of the ulna directly under the subcutane- ous skin. Examination should include wrist and elbow assessments to exclude any associated injuries involving the PRUJ or DRUJ. The emergency clinician should be aware of potential instability at either articulation associated with fractures involving the proximal or distal third of the ulna. Diagnostic Testing Diagnosis of an ulna fracture is made by obtaining AP and lateral radiographs of the full- length forearm (Fig. 43.35). Although most iso- lated ulna fractures are considered stable, those with more than 50% displacement, more than 8 degrees of angulation, involvement of the proximal third of the ulna, or instability at the DRUJ or PRUJ are con- sidered unstable fractures. Management and Disposition There is a controversy regarding the indication for the operative man- agement of isolated ulna shaft fracture; however, any unstable fractures should be referred to an orthopedist within 7 days for possible ORIF because they carry a high risk of function loss, nonunion, malunion, and radioulnar synostosis.16 Most stable ulna fractures heal without significant clinical sequelae. Stable fractures can be managed with 6 to 8 weeks of short arm, below- elbow immobilization with interosseous molding to limit radial angula- tion and prevent forearm rotation. Early mobilization with a removable forearm support achieves the earliest radiologic time to union and low- est rate of malunion. Above- elbow immobilization or long arm casting A B Fig. 43.33 Normal anteroposterior (A) and lateral (B) radiographic views of the forearm. Both bones should be visible for their entire length, and the radiograph should include the wrist and elbow joints. Fig. 43.34 Lateral Radiographic View of a Normal Elbow. A line bisecting the proximal radial shaft also bisects the capitellum (dotted line). A B Fig. 43.35 Isolated Ulna Fracture (Nightstick Fracture). Anteroposte- rior (A) and lateral (B) radiographic images show isolated ulnar fracture. 521CHAPTER 43 Wrist and Forearm Injuries may be detrimental to the healing process and have been associated with nonunion and delayed union. Monteggia Fracture Foundations Ulna fractures associated with radial head dislocation are commonly known as Monteggia fractures. Monteggia originally described a trau- matic lesion involving the fracture of the proximal third of the ulna and anterior dislocation of the radius. Bado later redefined the Monteggia fracture and classified it to encompass various ulna fractures with con- comitant radial head dislocations. The Bado classification divides the injury into four types depending on the location and angulation of the ulna fracture, along with the direction of the radial head dislocation. Clinical Features Patients with a Monteggia fracture often have fallen on an outstretched hand, resulting in hyperpronation. Direct posterior force on the ulna or a fall on the flexed elbow has also been implicated in the mechanism of the injury. Typically, patients have swelling and tenderness along the fracture site accompanied by a limited range of motion at the elbow and pain with pronation of the forearm. A dislocated radial head may be appreciated on palpation. Initial assessment of a Monteggia fracture should include a focused neurologic examination because the posterior interosseous nerve (PIN), a deep branch of the radial nerve, can be injured. Because the PIN innervates the finger extensors along with the supinator, PIN injury is often manifested by weakness or paralysis of the thumb or finger exten- sion. Complications of a Monteggia fracture include malunion, nonunion, synostosis, stiffness, and nerve palsy. Early diagnosis and treatment of a Monteggia fracture are crucial in achieving good outcomes. Diagnostic Testing The radiograph of the forearm reveals the obvious ulna fracture that often overshadows the subtle radial head dislocation (Fig. 43.36). A chronic, irreducible radial head dislocation can occur as a result of delay in diagnosis. Drawing the radiocapitellar line (RCL) through the head of the capitellum can prevent overlooking a proximal dislocation. The line should intersect the distal third of the capitellum on all views and confirm correct alignment. In young children however, an RCL may not reliably bisect the capitellum in normal pediatric patients. An abnormal RCL is suggestive of, but not pathognomonic for an injury. Management and Disposition Treatment of a Monteggia fracture depends on the age of the patient. Pediatric patients with this type of injury can be treated conserva- tively, with long arm casting in supination with acceptable reduction. Conversely, most adult patients with this type of fracture should have orthopedic evaluation to arrange for urgent ORIF. Galeazzi Fracture Foundations Galeazzi fracture refers to a fracture of the middle to distal third of the radius associated with injury to and dislocation of the DRUJ. Clinical Features Typically, a Galeazzi fracture results from a fall or motor vehicle col- lision as the patient attempts to brace for impact by stretching out the hand in hyperpronation. A direct blow to the dorsolateral aspect of the forearm is less common but also well recognized as a mechanism of injury for a Galeazzi fracture. Galeazzi fracture is often overlooked as a simple radius fracture, yet it often results in diminished forearm range of motion, loss of function, weakness, and chronic pain. In addition to radiographic imaging, the mechanism of injury and focused examination play a critical role in the diagnosis of a Galeazzi fracture because injuries to the DRUJ may not be obvious. Patients with Galeazzi fracture have deformity at the site of the fracture asso- ciated with swelling and tenderness. The wrist should be meticulously examined to assess for stability of the DRUJ. Instability of the DRUJ can range from obvious prominence of the ulnar head (associatedwith the subluxation or dislocation) to tenderness elicited at the wrist, which can be a subtle sign of DRUJ ligament injury. Diagnostic Testing AP and lateral radiographs of the entire forearm and wrist are neces- sary to diagnose Galeazzi fracture. Besides the obvious fracture at the middle to distal third of the radius, there will be other subtle radio- graphic findings. On the AP view of the forearm, the space between the distal radius and ulna is widened (>2 mm) and the radius appears relatively shortened. In the lateral view, the dorsally angulated frac- ture of the radius can cause a dorsal displacement of the ulnar head. A fracture at the base of the ulnar styloid should raise the suspicion for DRUJ interruption (Fig. 43.37). Although not all radius shaft fractures are associated with DRUJ injury, previous studies have shown that at least 25% of all patients with radius fractures have DRUJ dislocation. Therefore, patients with radial shaft fractures should be referred to an orthopedist for further evaluation. Management and Disposition Conservative management of a Galeazzi fracture in adults has been associated with poor outcomes. Due to deforming forces from differ- ent forearm muscles and loss of stability at the DRUJ, displacement of the alignment in the cast occurs, despite successful initial reduction. A Galeazzi fracture has been termed a “fracture of necessity” to imply that surgical intervention is pivotal for achievement of an ideal ana- tomic position and acceptable functional outcomes. For any skeletally mature patients with this fracture, an orthopedist should be consulted emergently for ORIF of the radius and associated repair of the DRUJ to maintain the length and alignment. In contrast, conservative treat- ment with closed reduction and long arm casting has been successful in children and rarely necessitates surgical intervention. Along with the common complications associated with forearm fractures, such as malunion and nonunion, the occurrence of subluxation and disloca- tion of the DRUJ can result in limited motion and chronic pain. Essex- Lopresti Lesion Foundations The Essex- Lopresti lesion, or longitudinal radioulnar disassociation, refers to an unstable forearm as a result of a triad of injuries to the radial head, disruption of the interosseous membrane, and violation of the DRUJ. Fig. 43.36 Monteggia Fracture- Dislocation. A fracture of the ulna diaphysis with anterior dislocation of the radial head (arrow) is shown in this lateral view of the forearm. 522 PART II Trauma Clinical Features The patient often has fallen on an outstretched hand, resulting in trans- mission of a large axial loading force from the wrist to elbow. Con- sequently, the radial head, the primary forearm stabilizer, is fractured and displaced proximally. Disruption of the interosseous membrane and DRUJ also occurs and compromises the stability of the forearm. In addition to localized pain along the elbow from a radial head frac- ture, patients with the Essex- Lopresti lesion have wrist and forearm pain, along with grip and pronation weakness. Radioulnar synostosis and loss of forearm rotation can result from longitudinal disassocia- tion. Early diagnosis of Essex- Lopresti injury and stabilization of DRUJ have been linked to favorable outcomes in comparison to delayed diagnosis.17 Diagnostic Testing The diagnosis of an Essex- Lopresti lesion remains elusive because the standard AP and lateral views of the forearm often reveal an isolated radial head fracture. Thus, the incidence of the lesion may be higher than previously appreciated. The integrity of the interosseous mem- brane is difficult to assess based on a plain film. Subtle findings of pos- itive ulna variance and a widened DRUJ are suggestive of longitudinal radioulnar dissociation. Obtaining a grip view and comparing the injured wrist with the contralateral wrist can be helpful in diagnos- ing an Essex- Lopresti lesion. MRI is the study of choice when clinical suspicion for an Essex- Lopresti lesion is high; however, ultrasound has recently been used more frequently to evaluate the integrity of the interosseous membrane. A CT scan (with three- dimensional recon- structions) of the elbow may be helpful in determining the degree of comminution and articular involvement of the radial head. Management and Disposition Once the diagnosis of an Essex- Lopresti lesion is confirmed, the patient should be referred to an orthopedic surgeon within 7 to 10 days for further surgical intervention. Many strategies have been proposed to repair Essex- Lopresti lesions, and the treatment option varies, depend- ing on the chronicity of the injury. ACKNOWLEDGMENT We would like to thank David Williams, Karen G.H. Woolfrey, Michael Woolfrey, and Mary A. Eisenhauer for their contributions to previous versions of this chapter. The references for this chapter can be found online at ExpertConsult. com. A B Fig. 43.37 Galeazzi Fracture- Dislocation. The anteroposterior (A) and lateral (B) views of the forearm show an obvious fracture of the distal third of the radius, with severe displacement and an associated disloca- tion of the distal radioulnar joint (arrow). http://ExpertConsult.com http://ExpertConsult.com 522.e1 REFERENCES 1. Sun B, Zhang D, Gong W, et al. Diagnostic value of the radiographic muscle- to- bone thickness ratio between the pronator quadratus and the distal radius at the same level in undisplaced distal forearm fracture. Eur J Radiol. 2016;85(2):452–458. 2. Loesaus J, Wobbe I, Stahlberg E, Barkhausen J, Goltz JP. Reliability of the pronator quadratus fat pad sign to predict the severity of distal radius fractures. World J Radiol. 2017;9(9):359–364. 3. Mallee WH, Wang J, Poolman RW, et al. 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In the setting of acute trauma and negative radiographs of the wrist, which clinical examination method(s) is (are) used to detect occult scaphoid fractures? a. Anatomic snuffbox tenderness b. Scaphoid tubercle tenderness c. Thumb metacarpal compression tenderness d. A positive Watson’s scaphoid shift test e. All of the above Answer: e. In the setting of acute trauma and negative radiographs, tenderness to palpation within the anatomic snuffbox, on the scaphoid tubercle, with thumb metacarpal compression, or a positive Watson’s scaphoid shift test are all suggestive of occult scaphoid fracture. 2. A 45- year- old man complains of wrist pain after falling on an out- stretched hand. What injury is shown in Figure 43.21 of the patient’s wrist? a. Barton’s fracture b. Lunate dislocation c. Perilunate dislocation d. Scaphoid fracture e. Scapholunate dissociation Answer: e. The radiograph shows the signet ring, or cortical ring sign, which refers to the rotary subluxation of the scaphoid and oval appear- ance of the tubercle in the anteroposterior (AP) view of the wrist. On a properly positioned radiograph, this sign is typically associated with scapholunate widening, suggesting ligamentous laxity or dissociation. The signet ring sign is also used to describe pulmonary computed tomography (CT) imaging of bronchiectasis in relation to a dilated bronchus and associated pulmonary artery. 3. A 55- year- old man complains of wrist pain after a fall onto an out- stretched arm. There is pain and swelling along the carpal bones. Also noted is decreased two- point sensation distally on the tips of the index and middle digits. Which structure is most likely injured? a. Median nerve b. Radial artery c. Radial nerve d. Ulnar artery e. Ulnar nerve Answer: a. The median nerve courses through the carpal tunnel on the volar aspect of the wrist. It provides sensation to most of the palm and thumb, half of the ring finger and, specifically, the tips of the index and middle digits. The median nerve is the most common neurapraxia associated with Colles fractures. 4. Which nerve is commonly associated with a Monteggia fracture? a. Muscular branch of the radial nerve b. Posterior interosseous nerve c. Deep branch of the ulnar nerve d. Median nerve e. Ulnar nerve Answer: b. Injury to the posterior interosseous nerve (PIN), a deep branch of the radial nerve, is commonly associated with a Monteggia fracture. Because the PIN innervates the finger extensors along with the supinator, associated injury is often manifested by weakness or paralysis of the thumb or finger extension. 5. A karate player presents with pain over the ulnar aspect of his hand. On physical examination, there is tenderness over the ulnar aspect of the wrist, distal to the volar crease. Paresthesias in the distribu- tion of the ulnar nerve are present and the patient also complains of hand clumsiness. Standard X- rays are negative. What additional view might reveal the diagnosis? a. Clenched fist view b. Carpal tunnel view c. Scaphoid view d. External Oblique view e. Metacarpal view Answer: b. Pisiform or hook of hamate fractures may cause the constel- lation of findings in the above scenario and are better appreciated on the carpal tunnel view. The clenched fist view is best for identifying scapholu- nate widening while the scaphoid view is optimal for identifying scaphoid fractures. The external oblique view would not optimize imaging of these two bones and the metacarpal view is not an actual view. 43 - Wrist and Forearm Injuries Foundations Anatomy, Physiology, and Pathophysiology Clinical Features Differential Diagnoses Diagnostic Testing Management and Disposition Carpal Injuries Scaphoid Fractures . Scaphoid fractures often occur after a fall on the outstretched hand, causing hyperextension of the wrist. These injuries are ... . Patients typically report radial-sided wrist pain distal to the radial styloid with decreased range of motion of the wrist an... . Radiographic imaging remains the cornerstone for the evaluation of acute wrist trauma, but radiographic diagnosis of scaphoid ... . To avoid complications associated with delayed diagnosis, such as occult fracture displacement and AVN, patients with suspecte... Lunate fractures . Fractures of the lunate are relatively uncommon. This injury tends to occur in persons with a congenitally short ulna . Patients will experience pain over the dorsum of the wrist, exacerbated by axial loading of the long finger metacarpal. On phy... . In the ED, wrist radiographs are utilized to assess for lunate fractures; however, fractures of the lunate may be difficult to... . To minimize the risk of AVN, clinically suspected lunate fractures should be immobilized due to the possibility of occult luna... Triquetral Fractures . There are two main patterns of triquetral fractures that are observed: triquetral body and dorsal cortical chip fractures. An ... . Patients will experience local tenderness over the dorsal wrist (in the setting of dorsal cortical chips) or volar wrist (avul... . A fracture to the triquetral body is best seen on the AP view. Dorsal triquetral chip fractures are best seen on the standard ... . Treatment of triquetral fractures involves immobilization in a short arm volar splint. Urgent orthopedic referral within 5 to ... Pisiform Fractures . The pisiform is unique because it is the only sesamoid-like carpal bone and attaches to the FCU tendon, articulating on its d... . Fractures of the pisiform usually occur from a fall on the outstretched hand but also may be seen after direct blows to the hy... . Pisiform fractures are poorly seen on routine wrist radiographs and are likely underreported. A reverse (supinated) oblique an... . Nondisplaced fractures of the pisiform generally carry a good prognosis and are treated conservatively, with immobilization in... Hamate Fractures . The hook or hamulus is the most common site of hamate fracture, although articular surfaces and body fractures are also seen . Fracture of the hook usually occurs from a fall on the outstretched hand or from a direct blow to the palm. A fracture to the ... . Hamate body and articular surface fractures are best seen on PA views of the wrist (Fig. 43.17). Standard wrist radiographs ha... . Confirmed hook of hamate fractures should be immobilized in a volar splint that includes the fourth and fifth MCP joints in fl... Trapezium Fractures . There are two main types of trapezium fractures, those involving the body and trapezial ridge . A direct blow to the adducted thumb causes fracture through the body of the trapezium, with transmittal of the force by the ba... . Although trapezium fractures may be seen on the AP view of the wrist, they are typically better visualized on oblique views (F... . Nondisplaced trapezium fractures are treated with immobilization in a short arm thumb spica splint, with orthopedic referral w... Capitate Fractures . The capitate lies in a central position in the distal carpal row and, because of this protected location, it is rarely fractur... . The mechanism generally is a direct blow to the dorsum of the wrist. Fractures may also be seen in association with perilunate... . Fractures usually are visibleon the standard PA view of the wrist, although the lateral and oblique views may be helpful in d... . Identified or suspected nondisplaced fractures of the capitate should be managed with immobilization in a short arm thumb spic... Trapezoid Fractures . Trapezoid fractures are rare, usually seen in association with other carpal injuries . The typical mechanism of injury is a direct blow down the long axis of the index metacarpal, which may result in isolated frac... . The fracture may be visible on routine PA views of the wrist; however, oblique views may be superior for visualization of the ... . Confirmed or suspected nondisplaced trapezoid fractures should be immobilized with a short arm thumb spica splint with urgent ... Carpal Instability . The Mayfield classification of carpal instability is comprised of four distinct stages. Each stage represents a sequential int... . Carpal ligamentous injury is caused by wrist hyperextension, ulnar deviation, and intercarpal supination. Patients with these ... . A stage I injury, or scapholunate dissociation, results in a characteristic widening of the scapholunate joint on the PA view,... . Carpal dislocation injuries need emergent orthopedic consultation in the ED for reduction and stabilization. ED management of ... Radiocarpal Dislocation . Radiocarpal dislocations and fracture dislocations are considered extremely rare and are typically associated with high-energ... . Patients are commonly involved in polytrauma scenarios. Dislocations may be volar or dorsal, although ulnar translation of the... . Radiographs of the wrist are typically sufficient to identify radiocarpal dislocations . Emergent reduction of these injuries is paramount because of the extensive soft tissue damage and commonly associated neurovas... Distal Radius and Ulna Injuries Colles Fracture . A Colles fracture refers to a transverse fracture of the distal radial metaphysis, which is dorsally displaced and angulated . Patients classically present with a “dinner fork deformity” on physical examination. The fracture usually is located within 2 ... . The PA view may show extension of the fracture into the radioulnar or radiocarpal joints and the amount of intraarticular step... . Most Colles fractures require ED reduction for restoration of radial length, correction of dorsal angulation (especially when ... Smith Fracture . Smith fracture is a transverse fracture of the metaphysis of the distal radius, with associated volar displacement and angulat... . The typical mechanism of injury involves a direct blow to the dorsum of the wrist or a fall onto the dorsum of the hand result... . The fracture is visible on PA and lateral radiographs of the wrist, but the lateral view best shows the degree of volar displa... . Treatment of this fracture involves closed reduction and immobilization in a splint if the fracture is extra-articular, as di... Barton Fracture . Barton fracture is an oblique intraarticular fracture of the rim of the distal radius, with displacement and dislocation of th... Clinical features . Volar and dorsal rim fractures are visible on PA and lateral wrist radiographs; however, the lateral view best shows the degre... . Treatment of these unstable fractures requires emergent orthopedic consultation for reduction and fixation. Closed reduction m... Hutchinson Fracture . Hutchinson fracture, or chauffeur’s fracture, is an intra-articular fracture of the radial styloid . The mechanism of injury is usually a direct blow or fall resulting in trauma to the radial side of the wrist. The term chauffe... . The fracture is seen best on the PA view of the wrist as a transverse fracture of the radial metaphysis, with extension throug... . Nondisplaced fractures may be immobilized in a sugar tong splint, with the patient given urgent orthopedic referral within 2 t... Distal Radioulnar Joint Disruption . Acute dislocation of the DRUJ can occur as an isolated injury, which is rare, or in association with a fracture to the distal ... . Certain characteristic findings on clinical examination may constitute the only clue to the presence of this injury. The typic... . Diagnosis often is difficult because when the injury occurs in isolation or is not suspected, plain radiographs commonly are r... . Treatment of DRUJ dislocations commonly requires emergent orthopedic consultation for reduction and stabilization. Closed redu... Soft Tissue Injuries of the Wrist Carpal Tunnel and Acute Carpal Tunnel Syndrome Foundations Clinical Features Differential Diagnoses Diagnostic Testing Management and Disposition De Quervain Disease Foundations Clinical Features Diagnostic Testing Management and Disposition Intersection Syndrome Foundations Clinical Features Diagnostic Testing Management and Disposition Anatomy, Physiology, and Pathophysiology Differential Diagnoses Diagnostic Testing: Radiology Shaft Fractures of Radius and Ulna Foundations Clinical Features Diagnostic Testing Management and Disposition Ulna Shaft Fractures Foundations Clinical Features Diagnostic Testing Management and Disposition Monteggia Fracture Foundations Clinical Features Diagnostic Testing Management and Disposition Galeazzi Fracture Foundations Clinical Features Diagnostic Testing Management and Disposition Essex-Lopresti Lesion Foundations Clinical Features Diagnostic Testing Management and Disposition References
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