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Wrist and Forearm Injuries
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.
Key Concepts
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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 parallelism , assist in the radiographic diagnosis of carpal injuries.
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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.
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Routine wrist radiographs which include anteroposterior (AP), lateral, and oblique projections, may fail to detect scaphoid fractures.
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Thumb spica immobilization is recommended for suspected scaphoid and other carpal fractures. Expedited orthopedic follow-up for repeat assessment, radiographs, or advanced imaging (e.g., MRI, CT, or bone scan) is indicated.
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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 fractures.
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Hamate and pisiform fractures are best visualized with a carpal tunnel or reverse supinated oblique radiograph.
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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).
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A Colles fracture is a transverse fracture of the distal radial metaphysis, which is dorsally displaced and angulated. The Smith fracture is a transverse fracture of the metaphysis of the distal radius, with associated volar displacement and angulation.
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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).
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, allowing 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 movements 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 intercarpal joints, distally to the metacarpal articulations. The only muscular 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 support, 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 individual 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 synovial sheath that extends proximally and distally to the retinaculum. 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 carpal 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 devascularization and avascular necrosis (AVN) when fractured. This is particularly 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, respectively. 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 ).
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 |
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 begins with 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 deformity 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 abductor 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 compartments of the wrist and is also used as a primary landmark for radiocarpal 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 prominence 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 traumatic 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) tendinopathy is another cause of ulnar-sided wrist pain, and may be associated 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 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 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. Perilunate 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 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 posteroanterior (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 process 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 terminate 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 positive 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 surfaces, known as carpal or Gilula arcs ( Fig. 43.5 ). Disruption of these curves or widening of the carpal spaces is an indication of carpal ligament 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 capitate 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 lateral 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 presence 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 pronator 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. , 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 diagnosis based on the mechanism of injury and physical examination 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 bone along its long axis. The carpal tunnel view is performed with the wrist hyperextended 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 ).
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.
Management and Disposition
There is a high incidence of radiographically occult wrist fractures. Thus, when radiographs are normal but significant localized pain persists, immobilization and a repeat examination should be arranged within 1 week. A thumb spica should be applied in the setting of suspected 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. , 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 follow-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 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. There is some evidence suggesting ultrasound may be more accurate in diagnosing scaphoid fractures than X-ray, but other studies show mixed results. , Thus, ultrasonography 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 diagnosis of most radiographically occult scaphoid fractures. Despite its high cost and variable availability, MRI has greater sensitivity for diagnosing scaphoid fractures and soft tissue injuries than CT. Despite extensive 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 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. A recent trial in the United Kingdom demonstrated improved cost savings, diagnostic accuracy, and patient satisfaction associated with immediate MRI in patients with clinically suspected scaphoid fracture with normal radiographic imaging. 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. , 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 flexion 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 fracture. 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 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 short arm 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 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.
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.
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