Chapter 12: Wrist

The wrist is comprised of eight carpal bones that articulate with the radius proximally and the metacarpals distally. Motions include flexion, extension, radial deviation, and ulnar deviation. The carpal bones are divided into a proximal row of four bones and a distal row of four bones (Fig. 12–1). The proximal row, from radial to ulnar surfaces, includes the scaphoid, lunate, and triquetrum. The distal row, from radial to ulnar surfaces, includes the trapezium, trapezoid, capitate, and hamate. The pisiform, a sesamoid bone enclosed in the sheath of the flexor carpi ulnaris tendon, lies adjacent to the volar surface of the triquetrum and does not articulate with the forearm bones or with any of the remaining carpal bones.¹

Of the forearm bones, only the radius articulates with the carpal bones. The ulna has a nonosseous fibrocartilaginous union with the triquetrum and the radius, known as the triangular fibrocartilage complex (TFCC). The ulna articulates with the radius at the distal radioulnar joint (DRUJ). An interosseous membrane, dorsal and palmar radioulnar ligaments, and the TFCC stabilize this joint. Injury to the bones or ligaments of the DRUJ may significantly affect wrist mechanics leading to subluxation or dislocation. If not treated properly, an injury to these structures may result in long-term limitation of movement, arthritis or painful range of motion.

The ligaments of the wrist are considered extrinsic if they join the carpal bones to the radius, ulna, or metacarpals, and intrinsic when they link the carpal bones to one another. The ligaments of the wrist are also classified as dorsal, volar, or interosseous. The volar ligaments are stronger than their dorsal counterparts and provide the greatest stability. Injury to these ligaments results in carpal instability and will be discussed later in this chapter.

Many important neurovascular structures pass through Guyon canal formed by the pisiform and the hook of the hamate (Fig. 12–2). The deep branch of the ulnar nerve and artery supply the three hypothenar muscles, the interossei, the two ulnar lumbricals, and the adductor pollicis. A fracture to either the hamate or the capitate may result in neurovascular bundle damage and subsequent impairment of normal function. The median nerve lies in close proximity to the volar surfaces of the lunate and the capitate and may be injured following a fracture or dislocation.

It is essential to understand the relationship between the tendons and the carpal bones. The tendon of the flexor carpi ulnaris virtually engulfs the pisiform in its attachment. The close proximity of the flexor carpi radialis to the tubercle of the trapezium is also noteworthy. Trapezium fractures may result in tendon damage with subsequent pain during normal motion.

Examination

A meticulous examination combined with an in-depth knowledge of wrist anatomy will aid in the accurate diagnosis of wrist injuries. Localized tenderness of a bone or joint usually indicates the involved structure.

The radial portion of the wrist has several significant palpable bony structures. With the hand held palm side down and deviated slightly in a radial direction and the thumb extended, the anatomic snuffbox becomes prominent (Fig. 12–3). The dorsal aspect is made up of the extensor pollicis longus, whereas the tendons of the extensor pollicis brevis and the abductor pollicis longus form the palmar border of the snuffbox. The proximal border of the box is the radial styloid, followed by the scaphoid at the proximal base and the trapezium at the distal base. If the thumb is now flexed, the first carpometacarpal joint is palpated distal to the trapezium (Fig. 12–4).

As the examiner moves over the dorsum of the wrist, Lister tubercle of the distal radius can be palpated (Fig. 12–5). This tubercle serves as a landmark in locating the lunate and the capitate. With the hand held in a neutral position, there is a small indentation in the skin corresponding to the capitate (Fig. 12–6A). With the hand in flexion, the lunate becomes easily palpable just distal to Lister tubercle (Fig. 12–6B). Lister tubercle and the capitate form a straight line that transects the third metacarpal (Fig. 12–7). The triquetrum can be palpated just distal to the ulnar styloid (Fig. 12–8).

The pisiform is easily palpated at the base of the hypothenar eminence on the volar surface of the wrist (Fig. 12–9A). The flexor carpi ulnaris tendon inserts into the pisiform and is best examined with the fist clenched and the wrist flexed. The hook of the hamate can be palpated by placing the interphalangeal (IP) joint of one’s thumb over the pisiform, with the distal phalanx directed toward the web space between the thumb and index fingers. With deep palpation, the hook of the hamate can be felt under the tip of the examiner’s thumb (Fig. 12–9B).

Lastly, the volar and radial structures include the tuberosity of the scaphoid and the tubercle of the trapezium. With the wrist radial deviated, the tuberosity of the scaphoid is the most prominent structure palpated. The trapezial ridge is found by palpating just distal to the scaphoid in the line in the same axes of the index finger.

Imaging

Standard plain radiographs are the first line modality in the diagnosis of suspected wrist injuries. The minimum number of radiographic views includes a posteroanterior (PA), lateral, and oblique with the wrist in a neutral position (Fig. 12–10). Other views may be indicated depending on the suspected site of fracture.

The carpal bones are visualized best in the PA view. The three carpal arcs should be identified (Fig. 12–11A). The first arc is outlined by the proximal joint surface of the scaphoid, lunate, and triquetrum. The second arc is made up of the distal joint surfaces of the proximal row. The third arc consists of the proximal articular surface of the lunate and hamate.^1,2 Any disruption of these arcs suggests injury—fracture, dislocation, or both. In addition, the spacing between the carpal bones is normally constant, independent of wrist positioning. A variation in spacing is abnormal and may reflect subluxation, arthritis, or an old fracture. The normal width between the scaphoid and the lunate is 1 to 2 mm in the PA projection. A distance ≥3 mm between the scaphoid and the lunate are abnormal and suggest carpal instability (scapholunate dissociation).

The oblique view is useful as it demonstrates the radial structures better. This radiograph is obtained with the wrist in 45 degrees of pronation. In this view, the distal scaphoid, trapezium, trapezoid, and first and second carpometacarpal joints can be seen more clearly than in the PA view.

The lateral view is first assessed for adequacy. The ulna should not project >2 mm dorsal to the radius. Once the lateral view is determined to be adequate, the clinician should note the dorsal aspect of the triquetrum. The ulnar styloid points to the dorsal aspect of the triquetrum on the lateral view. A dorsal avulsion fracture of the triquetrum will be identified only on the lateral view.

Carpal alignment is also assessed on the lateral view. Abnormalities in carpal alignment are a clue to carpal instability due to ligamentous injury. The clinician should first note that the radius, lunate, and capitate make up a straight line. It may be helpful to view the lateral wrist radiograph for this purpose in the horizontal plane. The scaphoid is projected over the lunate at its proximal portion, and as it extends more distally, it is positioned volarly. A line drawn through the center of the lunate and the center of the scaphoid should make an angle between 30 and 60 degrees. This angle is known as the scapholunate angle (Fig. 12–11B). The capitolunate angle is measured in a similar manner by drawing a line through the center of the capitate and lunate. The angle that these lines make should be less than 30 degrees (Fig. 12–11C).³

Additional views may be obtained to better visualize suspected fractures. A PA view with maximum ulnar deviation of the wrist (scaphoid view) will allow better visualization of the scaphoid. The carpal tunnel view is used to detect fractures of the hook of the hamate and pisiform. This radiograph is obtained with the wrist hyperextended and the beam directed across the volar aspect of the wrist. An additional oblique film with the hand supinated 45 degrees will better demonstrate the pisiform and the palmar aspects of the triquetrum and hamate.

Ninety percent of all wrist fractures will be visualized with the standard plain radiographic views. Compression fractures or minimally displaced carpal fractures may not be readily apparent on plain radiographs. Other imaging techniques, including computed ­tomography (CT), bone scans, and magnetic resonance imaging (MRI), may be necessary but are not routinely used on the initial visit. Careful assessment of bone surfaces with ultrasound may identify fractures not visualized on initial plain radiographs. Among other fractures, ultrasound has been used to detect occult fractures of the waist of the scaphoid and fractures of the hook of the hamate.⁴ Once a fracture is detected on ultrasound, CT imaging should be performed to more precisely define the type of fracture.

Carpal Fractures

The carpals are a complex set of bones that form multiple articulations. Because radiographs often reveal significant bony overlap, a careful history and clinical examination are necessary to accurately diagnose these fractures. The scaphoid is not only the most frequently fractured carpal bone, but it is also one of the most frequently missed carpal bone fractures. The triquetrum is the second most commonly fractured carpal bone and the lunate is the third most frequently fractured. Carpal fractures are associated with several common complications.

1. Other injuries. Patients often suffer a second fracture or ligamentous injury.

2. Nerve injury. Many carpal fractures are associated with at least a transient median nerve neuropathy. Fractures of the hook of the hamate or pisiform may be complicated by ulnar nerve compromise.

3. Poor healing. Carpal fractures and especially scaphoid fractures may suffer the sequelae of nonunion or avascular necrosis (AVN). In many patients, this is secondary to inadequate immobilization.

Scaphoid Fractures

The scaphoid is the most commonly fractured carpal bone, accounting for 60% to 70% of carpal injuries.^5,6 The high incidence of fractures relates to the size and the position of the scaphoid. The scaphoid is classified as a proximal carpal bone. Anatomically, however, it extends well into the area of the distal carpal bones. Radial deviation or dorsiflexion of the hand is normally limited by impingement of the radius on the scaphoid. With stress, fractures frequently result.

The blood supply to the scaphoid penetrates the cortex on the dorsal surface near the tubercle waist area. Therefore, there is no direct blood supply to the proximal portion of the bone. Because of this tenuous blood supply, scaphoid fractures have a tendency to develop delayed union or AVN.

It is imperative for the clinician to realize that a patient presenting with a “sprained wrist” may have an occult scaphoid fracture. This injury can often be excluded acutely on the basis of physical examination. As will be discussed later, normal radiographs do not exclude this fracture.

Scaphoid fractures are divided into four type—middle-third (waist), proximal-third, distal-third, and tubercle fractures (Fig. 12–12). This classification lists scaphoid fractures in order of decreasing frequency. Fractures of the scaphoid waist represent >50% of all scaphoid fractures.⁶ The more proximal the fracture line, the higher the incidence of complications (proximal > waist > distal > tubercle). Scaphoid stress fractures have also been reported.⁷

Mechanism of Injury

Scaphoid fractures commonly result from forceful hyperextension of the wrist. Simple falls from a standing height and sports injuries are the most common mechanisms of injury.⁶ The particular type of fracture is dependent on the position of the hand and forearm at the time of injury. Middle-third fractures occur secondary to radial deviation with hyperextension resulting in impingement of the scaphoid waist by the radial styloid process.

Examination

On examination, there is maximum tenderness over the floor of the anatomic snuffbox. Tenderness within the anatomic snuffbox has been shown to be 90% sensitive for detecting scaphoid fractures and has a specificity of 40%.^8,9 Palpation of the scaphoid tubercle for tenderness has a similar sensitivity (87%) with an improved specificity (57%). This test is performed by radially deviating the wrist and palpating over the palmar aspect of the scaphoid.⁹ Axial compression of the thumb in the line with the first metacarpal and supination against resistance may also elicit pain from a scaphoid fracture.^10,11 The most accurate examination for detecting the presence of an occult scaphoid fracture was shown to be the reproduction of pain when the patient pinched the tips of their thumb and index finger together or when they pronated their forearm.¹² In addition, ulnar deviation of the pronated wrist has been shown to produce pain in the anatomic snuffbox in patients with a scaphoid fracture and, in one small study, the absence of this finding had a negative predictive value of 100%.¹³

Imaging

Routine plain radiographs of the wrist including PA, lateral, and oblique views may demonstrate the fracture (Fig. 12–13). If a scaphoid fracture is suspected clinically, an ulnar-deviated scaphoid view should be obtained.¹⁴ Despite this additional film, up to 30% of scaphoid fractures may not be demonstrated on initial plain radiographs.¹⁵ In addition, these fractures can take up to 1 to 2 weeks to become evident on plain films. An indirect sign of an acute scaphoid fracture is displacement of the scaphoid fat stripe.¹⁶ This finding, however, was present in only 50% of radiographically occult scaphoid fractures in one study.¹⁷ In some instances, a comparison view of the uninjured wrist may also be helpful.

Although plain radiography remains the standard initial imaging technique, other imaging modalities should be considered. CT scan is the preferred modality to assess the intricacies of a scaphoid fracture, including fracture location and deformity. MRI is excellent in the detection of clinically suspected scaphoid fractures if initial radiographs are negative. Limited MRI of the wrist has been shown in multiple studies to be 100% sensitive for detecting scaphoid fractures, even in the acute setting.¹⁸ On ultrasound, scaphoid cortical interruption and an effusion in the radiocarpal joint are considered diagnostic of a scaphoid fracture.¹⁹

If a fracture is identified, displacement between the fracture fragments or an unexplained variation in position between the fragments on different views indicates an unstable fracture. Fracture dislocation usually implies dorsal displacement of the distal fragment and carpal bones. The proximal fragment and lunate generally maintain their normal relationship with the radius.

Scaphoid fractures are sometimes confused with a bipartite scaphoid. This is a rare congenital anomaly (incidence <0.5%) that may be mistaken for a waist fracture.²⁰ The presence of a normal smooth bony margin is indicative of this normal variant.

An old scaphoid fracture that has not healed properly should not be confused with an acute injury. Radiographically, nonunion will be associated with sclerotic fragment margins. In addition, the radiolucent distance separating the fragments will be similar to the distance between other carpal bones (Fig. 12–14).

Associated Injuries

The majority (90%) of scaphoid fractures have no associated injuries. Injuries associated with scaphoid fractures include the following:

• Radiocarpal joint dislocation

• Proximal and distal carpal row dislocation

• Distal radial fracture

• Bennett fracture of the thumb

• Lunate fracture or dislocation

• Scapholunate dissociation

Treatment

The treatment of scaphoid fractures is controversial and fraught with complications. In general, distal fractures and transverse fractures heal with fewer complications when compared with proximal or oblique fractures. Immobilization is recommended; however, the best method remains unclear.^21,22 The appropriate length of the thumb spica splint—short arm versus long arm—has been debated. In one prospective, randomized study, the time to union was longer (12.7 vs. 9.5 weeks), and the rate of nonunion was greater in patients treated with short-arm thumb spica immobilization.²³ A more recent systematic review of randomized trials reported that non-union rates and functional outcomes did not differ based on the cast type.²⁴ Another randomized study of 292 patients demonstrated no benefit for immobilization of the thumb. Despite this study, many orthopedists still prefer the thumb be immobilized.^25,26

As with other fractures, ice and elevation are important adjuncts in the initial management of scaphoid fractures. The management of scaphoid fractures is divided into (1) patients with clinically suspected scaphoid fractures without radiographic evidence, (2) nondisplaced scaphoid fractures, and (3) displaced scaphoid fractures.

Up to 30% of patients with clinically suspected scaphoid fractures who do not have plain radiographic evidence of such an injury will ultimately be diagnosed with a scaphoid fracture.^11,15,27,28 Therefore, it is our view that such patients should be treated as having a nondisplaced scaphoid fracture, and the wrist and forearm immobilized in a thumb spica splint. The thumb should be in a position as if the patient was holding a wine glass. The wrist should be splinted in slight flexion with neither ulnar nor radial deviation (Appendix A–7).²⁹

After 7 to 10 days, a repeat physical examination and radiographic examination should be performed. If a fracture is identified, a long-arm thumb spica cast should be applied for an additional 4 to 5 weeks (total of 6 weeks). This should be followed by a short-arm thumb spica cast until clinical and radiographic signs of union are clearly seen. If a fracture is not identified, but the examination remains clinically suspicious, the splint should be reapplied and the patient reexamined at 7- to 10-day intervals.²⁹

Alternative methods for the early detection of an occult fracture include bone scan, CT, and MRI. Bone scanning 4 days post injury is sensitive for the detection of occult scaphoid fractures, but has a high number of false-positive results.³⁰ CT scan is readily available to most emergency physicians, has an improved sensitivity over plain films, and is more sensitive and specific than bone scanning.¹⁵ A false-negative CT scan may still occur.²² MRI is very sensitive for the detection of occult scaphoid fractures; however, it is not readily available. In one study of patients with clinical suspicion of scaphoid fracture and negative plain films, MRI within the first 2 weeks of injury detected occult scaphoid fractures in 20% of patients, and in another 20% a fracture of the distal radius or another carpal bone was found.²⁸ Another noted advantage of MRI evaluation of the scaphoid is the demonstration of viability of the fracture fragments.^{29, 31–32}

A thumb spica splint (Appendix A–7) should be applied. If a nondisplaced distal fracture is noted a short-arm thumb spica splint can be used. If a nondisplaced mid-body or proximal scaphoid fracture is noted, a long-arm spica splint should be applied. Follow-up with a hand surgeon should be arranged within 5 to 7 days for definitive treatment.

Most fractures are evaluated with CT to precisely define the location, pattern, and displacement, as these factors are not always apparent on plain radiographs.²⁶ If the CT scan confirms that the fracture is truly nondisplaced, then a long-arm thumb spica cast is applied. After 6 weeks, a short-arm thumb spica cast is applied for the remaining duration of immobilization, totaling 8 to 12 weeks. At this time, clinical and radiographic signs of union are usually present and casting is discontinued. Due to their higher rate of complications, proximal-third fractures are immobilized for a greater duration (12 to 16 weeks) than middle or distal-third fractures (8 to 12 weeks).

Casting of nondisplaced scaphoid fractures has long been the standard practice but more recently early surgical intervention is being offered as an option to patients who want to return to full function more rapidly. Surgery may allow earlier discontinuation of a cast and subsequent return to work or sports. The risk of surgery must be weighed against the greater than 95% expected union rate with casting. Several authors also recommend primary operative management for proximal scaphoid fractures even if they appear nondisplaced due to their higher rate of nonunion.²¹

Displaced fractures have a nonunion rate of 50% to 55% (compared to 5%-15% in fully immobilized nondisplaced fractures) and therefore require more aggressive initial management.^33,34 With significant displacement, angulation, or comminution, consultation with a hand surgeon should be obtained. The patient should be placed in a thumb spica splint and referred to a hand surgeon for open reduction and internal fixation.^22,26 Absolute indications for internal fixation include displacement of 1 mm or 15 degrees of angulation.^35,36

Complications

The following complications of scaphoid fractures may occur despite optimum treatment.

1. AVN is associated with proximal-third fractures, displaced fractures, comminuted fractures or fractures that are inadequately immobilized. AVN will occur approximately 30% of the time with proximal fractures having the highest incidence.^1,26

2. Delayed union, malunion, or nonunion may be encountered. Nonunion may occur in as many as 5% to 10% of all cases. Risk factors associated with nonunion include proximal fractures, fracture instability, and delay in care.³⁷

3. Radiocarpal arthritis with subsequent wrist pain and/or stiffness.³⁸

Triquetrum Fractures

Triquetrum fractures are the second most common carpal bone fracture, representing 3% to 5% of all carpal fractures.³⁹ Triquetrum fractures can be divided into two types—dorsal chip (avulsion) fractures and transverse fractures (Fig. 12–15). The dorsal chip fractures are much more common; accounting for up to 93% of all triquetrum fractures.³⁹

Mechanism of Injury

Dorsal chip fractures are usually secondary to a hyperextension injury with the wrist in ulnar deviation. In this position, the hamate forces the triquetrum against the dorsal lip of the radius, resulting in fragment shearing. If the wrist is held in flexion during a fall, an avulsion fracture at the attachment of the strong dorsal ligaments may also occur.⁴⁰

Transverse fractures are secondary to a direct blow to the dorsum of the hand and are frequently associated with perilunate dislocations.

Examination

There will be dorsal swelling and tenderness localized over the area of the triquetrum (just distal to the ulnar styloid). Wrist extension may reproduce or exacerbate the pain.

Imaging

Dorsal chip fractures are visualized on the lateral radiograph (Fig. 12–16). In this view, the ulnar styloid usually “points” to the dorsal aspect of the triquetrum. Transverse fractures are best visualized on PA and oblique radiographs.

Associated Injuries

Triquetrum injuries are frequently associated with scaphoid fractures, scapholunate instability, distal radius and ulnar styloid fractures, and ulnar nerve injuries. The deep branch (motor) of the ulnar nerve lies in close proximity to the triquetrum and may be compromised.

Treatment

The wrist should be immobilized by applying a volar splint with the wrist in slight extension. This provides protection while allowing for icing and elevation. A short-arm cast can be placed in 3 to 4 days after the swelling has subsided. Chip fractures are generally of little consequence, as most go on to an asymptomatic fibrous union, but they do indicate underlying soft-tissue injury that must be allowed to heal with 4 to 6 weeks of cast immobilization.^39,41

Guidelines for treating triquetrum body fractures are less clear. Displacement and other carpal injuries must be excluded radiographically before treatment. Nondisplaced body fractures can be immobilized with a short-arm cast for 4 to 6 weeks. If there is >1 mm of displacement or other associated intercarpal ligamentous injuries, operative repair should be considered.^39,40

Complications

As mentioned earlier, damage to the deep branch of the ulnar nerve with subsequent motor impairment may accompany this fracture. The triquetrum possesses a rich vascular supply and therefore neither dorsal chip fractures nor transverse fractures are associated with AVN.

Lunate Fractures

Fractures of the lunate are rare and only make up approximately 0.5% to 6.5% of all carpal bone fractures.^42–44 These fractures usually result from high-energy trauma and are typically associated with other carpal and ligamentous injuries. The most common lunate fractures are lunate body fractures (Fig. 12–17) and dorsal avulsion fractures. Lunate body fractures may occur in any plane with varying degrees of comminution. As with scaphoid fractures, the clinical suspicion of a fracture mandates treatment to prevent the development of osteonecrosis of the lunate, also known as Kienböck’s disease.

Mechanism of Injury

Lunate fractures generally result from an indirect mechanism such as hyperextension (dorsal avulsion fracture). Fractures of the body of the lunate occur from direct axial compression. Although 75% of patients with Kienböck’s disease have a prior history of significant wrist trauma, chronic repetitive trauma can also lead to this condition.⁴⁵

Examination

Pain and tenderness will be present dorsally over the area of the lunate (just distal to Lister tubercle). In addition, axial compression of the third metacarpal will exacerbate the pain. Swelling may be minimal because of the intracapsular location of the lunate.

Imaging

A fracture line is often difficult to detect on routine wrist films. If a fracture is suspected clinically, CT scan and MRI are often necessary to make the diagnosis.³⁵ Both are more sensitive than plain radiographs for the detection of lunate fractures. Kienböck’s disease presents in four distinct radiographic stages. In stage I, the plain radiographs are generally normal. In stage II, lunate sclerosis is noted, whereas in stage III, lunate collapse becomes apparent (Fig. 12–18). Finally, in stage IV, severe lunate collapse is present with intra-articular degenerative changes in the surrounding joints.⁴⁵ MRI performed early may detect diminished blood flow to the lunate and early signs of Kienböck’s disease.

Associated Injuries

Other carpal fractures and carpal instability frequently accompany lunate fractures and it is important to exclude these injuries.

Treatment

As with scaphoid fractures, treatment should be initiated on the basis of clinical or radiographic evidence of a fracture.⁴⁶ It is generally recommended that the patient be immobilized in a long-arm thumb spica splint (Appendix A–7) with the MCP joints flexed to relieve the compressive forces across the lunate. Orthopedic referral after initial immobilization is strongly recommended. Definitive management includes cast immobilization for a total of 6 to 8 weeks in patients with nondisplaced fractures. Displaced (>1 mm) or unstable fractures require operative repair. Options for operative repair include Kirschner wires, cannulated screws, or suture anchors into the bone. The treatment of Kienböck’s disease is not standardized and is beyond the scope of this chapter.

Complications

Inadequately treated lunate fractures have a tendency to develop osteonecrosis of the proximal fragment. With time, there will be compression and collapse of this fragment; however, osteonecrosis may develop despite adequate treatment.

Capitate Fractures

The capitate is the largest of the eight carpal bones. It articulates with the scaphoid and the lunate proximally, the trapezoid and the hamate along its lateral surfaces, and the second, third, and fourth metacarpals distally. Isolated capitate fractures are extremely rare, accounting for only 1.3% of all carpal bone fractures.⁴⁷ Capitate fractures are usually transverse and most often nondisplaced due to the stability offered by the intercarpal ligaments (Fig. 12–19).

Mechanism of Injury

Two mechanisms of injury result in fractures of the capitate. A direct blow or crushing force over the dorsal aspect of the wrist may result in a fracture. Indirectly, a fall on the outstretched hand may also result in a fracture. Because of the capitate’s well-protected position in the center of the wrist, a high-energy force is required to result in a fracture.

Examination

Tenderness and swelling over the dorsal aspect of the hand in the area of the capitate will be present. Axial compression or movement of the third metacarpal will exacerbate the pain.

Imaging

In patients with nondisplaced fractures the initial radiographs are often nondiagnostic. In one study, 57% of initial radiographs failed to show the fracture or were read as normal.⁴⁸ If the initial radiographs are nondiagnostic but the clinical suspicion of a fracture remains high, CT or MRI should be considered.

Associated Injuries

Most capitate fractures are associated with additional wrist injuries including scaphoid fractures, distal radius fractures, lunate dislocations or subluxations, or carpometacarpal dislocations. An entity known as scaphocapitate syndrome is a unique injury that causes a scaphoid waist fracture and proximal capitate fracture.³⁵

Treatment

The extremity should be immobilized in a short-arm thumb spica splint (Appendix A–7) with the wrist in slight dorsiflexion and the thumb immobilized to the IP joint in the wine glass position. Definitive management requires casting for 8 weeks for nondisplaced fractures. If significantly displaced, open reduction and internal fixation are indicated with early mobilization following surgery.

Complications

Capitate fractures may be associated with several complications.

1. Malunion or AVN

2. Post-traumatic arthritis is noted frequently after comminuted capitate fractures

3. Median nerve neuropathy or carpal tunnel syndrome

Hamate Fractures

The body of the hamate articulates distally with the bases of the fourth and fifth metacarpals, radially with the capitate and proximally with the triquetrum and lunate. The hook of the hamate is the distal border of Guyon canal that contains the ulnar artery and nerve. Hamate fractures account for 1% to 4% of all carpal fractures. These fractures can be divided into four types on the basis of location with fractures of the hook of the hamate being the most common type (Fig. 12–20).

1. Distal articular surface

2. Hook of the hamate

3. Comminuted body

4. Proximal pole articular surface

Mechanism of Injury

Each type of hamate fracture is generally secondary to a particular mechanism of injury. Distal articular surface fractures typically result from a fall or blow to the flexed and ulnar-deviated fifth metacarpal shaft. Fractures of the hook of the hamate are common in athletes involved in racket sports. During a forceful swing, the base of the racket (golf club, bat, etc.) compresses the hook, resulting in a fracture. A fall on the outstretched dorsiflexed hand can also result in these fractures. Direct crushing forces produce comminuted body fractures. Proximal pole or osteochondral fractures are impaction injuries that generally occur with the hand dorsiflexed and in ulnar deviation.

Examination

Tenderness is usually localized over the hypothenar eminence. Swelling may be minimal or absent. Distal articular fractures exhibit increased pain with axial compression of the fifth metacarpal. Hook fractures exhibit tenderness over the palm of the hand in the area of the hamate hook (2 cm distal and radial to the pisiform) (Fig. 12–9). Pain is reproduced when the fourth and fifth digits are extended against resistance while the wrist is held in slight ulnar deviation. With this maneuver, known as the hook of the hamate pull test, the flexor tendons become taut against the fractured hook and cause pain. Fractures of the body and proximal articular surface demonstrate increased pain with wrist motion.

Imaging

Routine radiographs, including oblique views, may not be adequate in demonstrating hamate fractures.⁴⁹ Hamate body fractures may be visualized with standard wrist views (Fig. 12–21). The hook of the hamate is best visualized with a carpal tunnel view or CT scan (Fig. 12–22).⁵⁰ CT scanning has a sensitivity of 100% and a specificity of 94% for detecting fractures of the hook of the hamate.⁵¹

Of note, the hook of the hamate develops from a different ossification center and in some adults may persist as a separate small round ossicle (os hamulus proprium). This normal variant can be misinterpreted as a hamate fracture.

Associated Injuries

Ulnar nerve or arterial injuries frequently accompany these fractures. In addition, rupture of the flexor tendons (flexor digitorum profundus) has been reported.

Treatment

Nondisplaced hamate fractures are treated with an ulnar gutter splint for wrist immobilization (Appendix A–3) followed by a short-arm cast for a period of 6 to 8 weeks. All displaced fractures of the body and hook fractures where the patient cannot tolerate prolonged immobilization should be referred for operative intervention after the extremity has been splinted. Displaced or nonunited hamate hook fractures are treated with excision.

Complications

Fractures of the hamate, particularly the hook, can injure branches of the ulnar artery and nerve and thus it is important to ensure that blood flow and sensation is intact to the fourth and fifth digits. Ulnar nerve injuries may result in interosseous atrophy with possible loss of grip strength.³⁴ In addition, hamate fractures may be followed by arthritis at the fifth carpometacarpal joint.

Trapezium Fractures

Trapezium fractures represent 1% to 5% of all carpal fractures.^35,52 Isolated fractures are rare. These fractures usually occur in association with other injuries, such as fracture/dislocations of the first metacarpal, scaphoid fractures, and distal radius fractures. Trapezium fractures may be classified into three types (Fig. 12–23).

1. Vertical fractures

2. Comminuted fractures

3. Avulsion fractures (trapezial ridge fracture)

Mechanism of Injury

Trapezium fractures are generally the result of one of three mechanisms. Vertical and comminuted fractures occur when the adducted thumb is driven forcefully into the articular surface of the trapezium. The bone is crushed between the radial styloid process and the first metacarpal. The trapezial ridge is a longitudinal palmar projection off the trapezium that serves as the radial attachment for the transverse carpal ligament. The trapezial ridge is fractured after direct trauma, such as a fall on an outstretched hand, or when the transverse carpal ligament causes an avulsion fracture.

Examination

The patient with a trapezium fracture will note pain at the base of the thenar eminence. They typically present with minimal swelling but may have significant discomfort (more than expected from other carpal bone fractures).³⁵ In addition, the pain will be increased with thumb motion or axial compression of the thumb. In particular, there may be pain and weakness with pinching (e.g., making the “OK” sign or touching the thumb to the tip of the fifth digit).

Imaging

Trapezium fractures can be difficult to visualize on standard radiographic views. Routine studies may be adequate in demonstrating vertical and comminuted fractures (Fig. 12–24A). A carpal tunnel view or CT scan may reveal a fracture of the trapezial ridge (Fig. 12–24B).⁵³

Associated Injuries

Trapezium fractures may be associated with radial artery injury, first metacarpal fractures, distal radial fractures, and first metacarpal dislocations. The flexor carpi radialis courses along the base of the trapezial ridge and is therefore frequently injured following a fracture.

Treatment

The emergency management of these fractures includes elevation and ice. Immobilization with a short-arm thumb spica splint is recommended (Appendix A–7). Nondisplaced fractures and avulsion fractures can be managed with cast immobilization whereas displaced fractures (>1 mm) require operative repair.

Complications

Trapezium fractures may be complicated by the development of arthritis involving the first metacarpal joint or tendonitis or rupture of the flexor carpi radialis.

Pisiform Fractures

The pisiform is a sesamoid bone that lies on the volar surface of the wrist. It is unique in that it articulates only with one bone, the triquetrum. The pisiform is rarely fractured and accounts for only 1% of all carpal bone fractures.³⁹ Anatomically, it is important to recall that the deep branch of the ulnar nerve and artery pass in close proximity to the radial surface of the bone within Guyon canal. In addition, the tendon of the flexor carpi ulnaris attaches to the volar surface of the pisiform.

Pisiform fractures are classified as follows (Fig. 12–25):

1. Avulsion fractures

2. Transverse body fractures

3. Comminuted fractures

Mechanism of Injury

There are two common mechanisms resulting in pisiform fractures. A direct blow or fall on the outstretched hand can result in a transverse or comminuted body fracture. Indirectly, a fall on the outstretched hand with tension on the flexor carpi ulnaris may result in an avulsion fracture.

Examination

Tenderness will be present over the area of the pisiform (base of the hypothenar eminence). Ulnar sided wrist pain can be elicited with resisted wrist flexion. Always examine and record the function of the motor branch of the ulnar nerve when a pisiform fracture is suspected.

Imaging

Diagnosis of a pisiform fracture is difficult on standard views because the adjacent and overlying bones prevent an unobstructed view. If not seen on standard radiographs, the pisiform may be visualized with a carpal tunnel view or an oblique film with the wrist supinated 30 to 45 degrees. Alternatively, a CT scan will usually delineate a fracture.

Associated Injuries

Pisiform fractures may be associated with the following:

• Damage to the motor branch of the ulnar nerve

• Triquetrum fractures

• Hamate fractures

• Distal radial fractures

Treatment

Initial treatment includes immobilization with an ulnar gutter splint (Appendix A–3). Definitive management consists of a short-arm cast for 6 weeks followed by active movement of the flexor carpi ulnaris. Excision of the pisiform is necessary in cases of nonunion.⁴³

Complications

Complications related to a missed pisiform fracture include pisotriquetral chondromalacia or subluxation, loose fragments in the joint space, and degenerative arthritis. Pisiform fractures may be complicated by an impairment of the deep branch of the ulnar nerve. However, most ulnar nerve palsies that are present at initial presentation will resolve in 8 to 12 weeks and require only close observation.³⁹

Trapezoid Fractures

Trapezoid fractures are exceedingly rare (<1% of carpal fractures) due to the strong ligamentous attachments to the adjacent carpal bones (Fig. 12–26).^39,54 Its keystone shape and position afford protection. Consequently dorsal dislocation is much more common than fracture.

Mechanism of Injury

Fractures are most often due to a crush injury (direct dorsal trauma) or a high-energy axial force that pushes the second metacarpal into the trapezoid.

Examination

Point tenderness over the dorsal aspect of the wrist proximal to the base of the second metacarpal is noted. Concomitant injuries may obscure this finding. Gentle motion of the second metacarpal may elicit pain.

Imaging

Trapezoid fractures are hard to visualize on standard wrist views. With several structures overlapping on these views, CT scan is the best imaging modality if the index of suspicion is high for fracture. Dislocations are best seen on the AP view as evidenced by a loss of the normal linear relationship with the proximal joint surface of the second metacarpal.

Associated Injuries

A fracture of the trapezoid rarely occurs in isolation.⁵⁴ Fractures or dislocations of the adjacent metacarpal bases are frequently associated. Dorsal dislocation of the trapezoid can occur. It is reduced using longitudinal traction followed by palmar flexion of the wrist and dorsal pressure on the trapezoid.³⁹

Treatment

Initial management consists of ice and elevation. Immobilization with a thumb spica splint (Appendix A–7) should be provided.⁵¹ Definitive management consists of cast immobilization or operative repair, depending on the degree of stability.

Complications

These fractures have a high incidence of nonunion and AVN.⁵⁴ As the trapezoid receives 70% of its interosseous blood supply through dorsal branches, dorsal fracture/dislocations often disrupt the blood supply increasing the risk of AVN.³⁹

Distal Radius Fractures

Distal radius fractures are among the most common long bone fractures encountered in the emergency department (ED). It has been noted that there is a bimodal distribution of these injuries primarily affecting children/adolescents and the elderly.^55–57 These fractures include; extension-type fractures (Colles), flexion-type fractures (Smith), and push-off fractures (Hutchinson and Barton). Each of these types of distal radius fractures will be considered separately after a brief review of the essential anatomy. The classification systems for distal radius fractures are complex. We will discuss one of these classification systems and provide practical guidance to the emergency physician treating these injuries.

Essential Anatomy

The emergency physician should be aware of the essential anatomy of the distal radius to assess three important measurements which can be identified on a radiograph of the wrist: volar tilt, radial tilt, and radial length. Restoration of normal anatomy accomplished by either closed reduction and/or operative fixation will be necessary to insure a good functional outcome. Failure to correct deformities may lead to abnormal wrist biomechanics and motion, and the development of traumatic arthritis.

The normal radiocarpal joint angle is measured on the lateral view and ranges from 1 to 23 degrees (average of 11 degrees) in a volar direction (volar tilt) (Fig. 12–27A). Fractures associated with volar angulation generally result in good functional recovery whereas fractures associated with dorsal angulation of the radiocarpal joint will have a poor functional recovery if adequate reduction is not accomplished.

The normal angulation of the radioulnar joint seen on the PA view of the wrist is 15 to 30 degrees (radial tilt) (Fig. 12–27B). The evaluation of this angle is essential when treating fractures of the distal radius because inadequate reduction resulting in loss of this angle will lead to an inhibition of ulnar hand motion.

This is also viewed on the PA view of the wrist. This measurement is drawn perpendicular to the radial shaft and is the distance from the tip of the radial styloid to the distal articular surface of the ulna (Fig. 12–27C). Normal radial length is 12 mm. If restoration of radial length cannot be restored after closed reduction, operative fixation may be necessary. In a study of displaced intra-articular radius fractures, restoration of radial length by operative intervention was more strongly correlated with improved functional status than restoration of radial or volar tilt.⁵⁸

Classification

Many classification systems have been described for fractures of the distal radius.^55,57,59 Ideally, a classification system would allow the treating physician to classify an injury and initiate treatment with an understanding of the expected outcome. However, because of the large number of variables, no single classification system is optimal, with some being more clinically applicable than others.

More recently, Fernandez proposed a classification system based on mechanism of injury with the added benefit of offering guidelines for treatment.⁶⁰ This system is as follows:

Type I: Extra-articular metaphyseal bending fractures

Colles (dorsal angulation) and Smith (volar angulation)

Type II: Intra-articular shearing fractures

Barton (dorsal and volar)

Type III: Intra-articular compression fractures

Complex articular and radial pilon fractures

Type IV: Avulsion fractures

Radiocarpal fracture dislocations

Type V: High-velocity mechanism with extensive injury

Type I fractures can be reduced by the emergency physician. Type II through V fractures may undergo initial closed reduction in the ED; however, due to a high rate of complications, it is recommended that these patient all have very close orthopedic follow up as many of these cases will require operative intervention.

Most type I distal radius fractures can be managed nonoperatively after successful closed reduction (for displaced fractures). In most cases, types II through V fractures will ultimately require operative management due to their unstable nature.

Unstable fractures that are at high risk for secondary displacement even when properly casted after initial reduction include fractures of the distal radius that show on initial radiographs more than 20 degrees of dorsal or volar angulation, displacement more than two-thirds the width of the shaft in any direction, metaphyseal comminution, more than 5 mm of shortening, an intra-articular component, an associated ulna fracture, or advanced osteoporosis.⁶¹

A major limitation of most classification systems for distal radius fractures is that the radiographic appearance of the fracture does not necessitate a particular treatment method. Many other factors, including patient’s age and functional status, occupation, bone density, surrounding soft-tissue injury, and the stability of closed reduction, are important to the orthopedic surgeon when considering the need for operative fixation. Osteopenia increases the need for operative fixation, as adequate closed reduction is at times difficult to maintain.

Associated Ulna Fractures

Fractures of the distal ulna are frequently associated with distal radius fractures and may contribute to the need for operative intervention. Approximately 60% of distal radius extension-type fractures are associated with fractures of the ulnar styloid, and 60% of ulnar styloid fractures are associated with fractures of the ulnar head or neck. Ulnar styloid fractures signify avulsion by the ulna collateral ligament complex. However, this injury is rarely significant, and appropriate treatment of the distal radius fracture is all that is necessary. Ulnar head or neck fractures may create an unstable DRUJ and therefore, these fractures should be referred to an orthopedic surgeon for follow-up.

Extension-Type (Colles) Fracture

The distal radius is one of the most frequently fractured long bones and the extension-type or Colles fracture is the most common wrist fracture seen in adults⁶² (Fig. 12–28).

Mechanism of Injury

Most distal radius fractures occur as a result of a fall on an outstretched hand. The amount of comminution and location of the fracture line is dependent on the force of the fall and the brittleness (age) of the bone. A supinating force often results in an associated ulnar fracture.

Examination

Examination typically reveals pain, swelling, and tenderness of the distal forearm. The displaced angulated fracture typically resembles a dinner fork (Fig. 12–29). Documentation of the neurologic status with special emphasis on median nerve function should be stressed. Elbow or proximal forearm tenderness may be indicative of proximal radial head subluxation or dislocation.

Imaging

A PA and lateral view of the wrist is usually sufficient for demonstrating the fracture⁶³ (Fig. 12–30). Colles fractures are characterized by dorsal displacement or angulation of the distal radius (Fig. 12–31). Frequently impaction of the dorsal cortex is noted. With more severe forces, comminution of the distal cortex of bone and intra-articular extension is seen.

When evaluating these fractures, the physician should address the following questions:

1. Is there an associated ulnar styloid or neck fracture (Fig. 12–32)? These fractures may create an unstable DRUJ and require more urgent orthopedic referral.

2. Does the fracture involve the radioulnar or radiocarpal joint? The more intra-articular involvement, especially if a step-off is present, the more likely traumatic arthritis will develop. CT or MRI may be helpful in delineating the extent of radiocarpal or radioulnar involvement, however, these tests may be performed on an outpatient basis.

3. What are the measurements of the volar tilt (lateral), radial tilt (PA), and radial length (PA)? Loss of the normal anatomy increases the risk of complications.

4. Is there evidence of distal radioulnar subluxation on the lateral radiograph? The ulna should not project more than 2 mm dorsal to the radius on a true lateral radiograph. Distances >2 mm suggest distal radioulnar subluxation.

Associated Injuries

Extension-type fractures of the distal radius can be associated with several significant injuries including ulnar styloid and neck fractures, carpal bone fractures, distal radioulnar subluxation, ligamentous injuries, flexor tendon injuries, and median and ulnar nerve injury.

Treatment

Colles fractures which are nondisplaced and nonangulated with near-normal radial tilt, volar tilt, and radial length can be immobilized in a volar or sugar-tong splint (Appendix A–11).^61,64 Other nondisplaced distal radius fractures are managed the same way. For displaced or angulated fractures with loss of normal anatomical alignment, closed reduction is performed either by a consulting orthopedist or the emergency physician if they are comfortable with the procedure.

Closed reduction of Colles fractures are carried out in the following manner (Fig. 12–33 and Video 12–1):

1. Adequate anesthesia should be provided with a hematoma block or procedural sedation (see Chapter 2 and Video 12–2).

2. Distraction: The fingers should be placed in finger traps and the elbow in 90 degrees of flexion. Tape placed around the fingers will protect the skin and prevent the fingers from slipping out. Approximately 5 to 10 lb of weight is suspended from the elbow for a period of 5 to 15 minutes or until the fragments disimpact. Four bags of saline in a sling or stockinette weighs almost 9 lb and can be used as an alternative to traditional weights (Fig. 12–34). Alternatively, traction-countertraction can be used to distract the fragments (Video 12–3).

3. Disengagement: With the thumbs on the dorsal aspect of the distal fragment and the fingers grasping around the wrist, the force of the injury is recreated by slight extension of the distal fragment to disengage the fracture fragments.

4. Reapposition: While maintaining traction, pressure is applied over the distal fragment in a volar direction with the thumbs, and dorsally directed pressure over the proximal segment with the fingers.

5. Release: When proper positioning has been achieved, the traction weight is removed. If fluoroscopy is available, the success of the reduction can be evaluated immediately.

When reduction is complete, the forearm is immobilized and median nerve function is retested and documented. Preparation of the splint materials before the reduction attempt will allow more rapid immobilization once the fracture is reduced. The forearm is wrapped in a thin layer of padding followed by the application of a sugar-tong splint (Appendix A–11). Too much padding or the use of commercially available fiberglass splint material is not recommended because the reduction is less likely to be maintained. Colles fractures are typically immobilized in slight pronation (25 degrees) with the wrist in 15 degrees of palmer flexion and 10 to 15 degrees of ulnar deviation.⁶¹ Postreduction radiographs are obtained to ensure proper reduction. After reduction, the arm should remain elevated for 72 hours to keep swelling at a minimum. Finger and shoulder exercises should begin immediately.

In reducing distal radius fractures, several principles must be remembered. First, patients who present in a delayed fashion (i.e., in terms of days) are more difficult to reduce, and performing a hematoma block will often not be an effective pain management. Second, dorsal angulation (tilt) is not acceptable and volar tilt is difficult to maintain because the extensors of the hand have a tendency to exert dorsal traction. In addition, restoration of normal radial tilt is easily achieved with reduction but frequently difficult to maintain during the healing phase. Radiographs to document that proper reduction is maintained should be obtained at 3 days and 2 weeks post injury. If the reduction cannot be maintained, internal fixation might be required. Guidelines for adequate reduction have been described and include⁵⁵:

1. Radial inclination: 15 degrees or greater on PA view

2. Radial length: 5 mm or less shortening on PA view

3. Radial tilt: Less than 15-degree dorsal or 20-degree volar tilt on lateral view

4. Articular incongruity: 2 mm or less of step-off

Colles fractures, even when managed appropriately, can result in long-term complications.^65,66 For this reason, follow-up with an orthopedist is recommended within 1 week, especially when a fracture is reduced in the ED. Nondisplaced fractures should remain immobilized for 4 to 6 weeks whereas displaced fractures that are adequately reduced require 6 to 12 weeks of immobilization.

Unstable fractures may require percutaneous pinning, internal fixation, or external fixation.^67,68 Other indications for surgery include open fractures, severely comminuted or displaced (>2 mm) intra-articular fractures, and fractures with greater than 3 mm of dorsal displacement or 10 degrees of dorsal angulation after an attempt at closed reduction. Delay beyond 2 to 3 weeks makes operative intervention more difficult because the fracture fragments cannot be manipulated.

Complications

Complications associated with Colles fractures are commonly reported in the literature.^69–71 These complications include neuropathies, degenerative arthritis, malunion, tendon injury, compartment syndrome, and reflex sympathetic dystrophy. Limitation of wrist function after these fractures has been reported to be as high as 90%.⁷² Early adequate reduction of the fracture is the most important early aspect of care to reduce complications. Complications of these fractures are typically described as immediate, early (<6 weeks), and late (>6 weeks).⁶⁹

Immediate complications include nerve injury with the median nerve being most commonly affected. Acute carpal tunnel syndrome is more common in patients with severe comminuted fractures and those requiring multiple closed reduction attempts. Other immediate injuries include skin injury during manipulation or as a result of an open fracture, compartment syndrome (rare), or missed associated injuries.

Early complications include median nerve dysfunction, tendon injury, ulnar nerve injury, compartment syndrome, and fracture fragment displacement. The patient with median nerve compression will usually complain of pain and paresthesias over the distribution of the median nerve. If casted, the cast and padding should be split and the arm elevated for 48 to 72 hours. If the symptoms persist, carpal tunnel syndrome should be suspected. Caution: The function of the median nerve in distal forearm fractures should always be documented. Persistent pain should be regarded as secondary to median nerve compression until proven otherwise. Other early complications include infection either as a result of an open fracture or operative fixation (percutaneous pinning or internal plate fixation).

Late complications include stiffness of the fingers, shoulder, or radiocarpal joint; reflex sympathetic dystrophy; cosmetic defects may follow displaced fractures; rupture of the extensor pollicis longus; malunion or nonunion; flexor tendon adhesions; chronic pain over the radioulnar joint with supination.

Flexion-Type (Smith) Fracture

This fracture has often been described as a reverse Colles fracture. It is an uncommon fracture, outnumbered compared to Colles fractures by a factor of 10:1. A Smith fracture rarely involves the DRUJ. The classification system, developed by Thomas, has both therapeutic and prognostic implications.⁷³

Mechanism of Injury

Several mechanisms can result in these types of distal forearm flexion fractures, including a fall on a supinated forearm with the hand in dorsiflexion, a punch with the fist clenched and the wrist slightly flexed, or a direct blow to the dorsum of the wrist or distal radius with the hand flexed and the forearm in pronation.

Examination

Pain and swelling will be apparent over the volar aspect of the wrist. The clinical appearance of this fracture is described as a garden spade deformity (Fig. 12-35A). The presence and function of the radial artery and median nerve should be examined and documented.

Imaging

Routine PA and lateral views are adequate for demonstrating this fracture (Fig. 12–35B). Smith fractures are characterized by volar displacement and volar angulation of the distal radius.

Associated Injuries

Carpal fractures or dislocations are uncommonly associated with these fractures.

Treatment

These fractures require emergent orthopedic referral for reduction. If orthopedic referral is unavailable, the fracture may be reduced as follows. Traction is applied using finger traps with 8 to 10 lb of weight at the flexed elbow. The wrist is then flexed until the fragments are disimpacted. With the thumbs against the distal fragment, dorsal pressure is applied until the fragments are properly positioned. The forearm should be immobilized in a sugar-tong splint (Appendix A–11). Postreduction radiographs for documentation of reduction should be obtained. If the reduction remains stable, this fracture can be definitively treated with casting, although these fractures more frequently require surgery. Unstable fractures require pin or plate fixation. Patients with intra-articular involvement require urgent referral for pinning of the bony fragment.

Complications

Complications seen with these fractures include tendon damage, nerve compression, and the development of osteoarthritis.

Dorsal and Volar Rim (Barton) Fracture

These fractures are intra-articular and involve the dorsal or volar rim of the distal radius (Fig. 12–36). Using the classification scheme described by Fernandez, Barton fracture is described as a type II shearing mechanism fracture. These fractures require operative repair if the fracture fragment is large or unstable. Barton fractures most commonly involve the dorsal rim of the distal radius (classic Barton fracture), and typically a triangular fragment of bone is noted on a lateral radiograph of the wrist.

Mechanism of Injury

Extreme dorsiflexion of the wrist accompanied by a pronating force may result in a dorsal rim fracture.

Examination

The distal dorsal radius is tender and swollen. Occasionally, radial nerve sensory branches may be compromised and present as paresthesias in the area of distribution.

Imaging

Lateral radiographs adequately demonstrate the fracture fragment and the degree of displacement (Fig. 12–37).

Associated Injuries

Carpal bone injury or dislocations along with damage to the sensory branches of the radial nerve may occur.

Treatment

Management depends on the size of the fracture fragment and the degree of displacement. Nondisplaced Barton fractures should be placed in a sugar-tong splint (Appendix A–11) with the forearm in a neutral position. A large displaced fragment with subluxation or dislocation of the carpal bones requires procedural sedation followed by a closed reduction. If the fracture is stable and in a good position, a sugar-tong splint (Appendix A–11) with the forearm in a neutral position is recommended. If the fracture is unstable or reduced inadequately, open reduction with internal fixation is indicated. A small fragment may be reduced and fixed by the placement of a percutaneous pin.

Complications

Frequent complications include arthritis secondary to intra-articular involvement as well as those complications associated with Colles fractures.

Radial Styloid (Hutchinson) Fracture

This fracture is also known as a chauffeur’s or backfire fracture. The term originated in the era of hand-cranked automobiles. The injury historically occurred as a result of recoil of the crank⁶² (Fig. 12–38).

Mechanism of Injury

The mechanism involved is similar to that seen in a scaphoid fracture. Here, the force is transmitted from the scaphoid to the styloid.

Examination

Pain, tenderness, and swelling are noted over the radial styloid.

Imaging

A PA radiograph of the wrist best demonstrates this fracture (Fig. 12–39).

Associated Injuries

Fractures of the scaphoid as well as scapholunate dissociation may be associated with these fractures.⁶⁷ Up to 70% of radial styloid fractures have extension of injury into the scapholunate ligaments.

Treatment

The forearm should be immobilized in a sugar-tong splint (Appendix A–11) with ice and elevation. These patients require urgent orthopedic referral as percutaneous fixation is indicated for unstable fractures.

Complications

Complications of these fractures include degenerative arthritis and associated scapholunate ligament disruption.

Ligamentous Injury

Carpal stability is maintained by a complex array of ligaments connecting the bones of the wrist to one another. Ligaments are located on the volar and dorsal sides of the wrist as well as the intraosseous spaces. The volar ligaments are stronger than the dorsal ligaments with the exception of the space of Poirier, an area on the volar aspect between the lunate and capitate that is often the site of carpal dislocation. Injury to the carpal ligaments can result in loss of the normal alignments of the carpal bones, carpal dislocation, or a combination of the two. With enough force, an associated fracture may occur (scaphoid, capitate, triquetrum, radial, or ulnar styloid). The most common mechanism for these types of injuries is a fall on an outstretched hand, however a direct blow, distraction, and torquing motions can also produce these injuries.

Carpal instability and associated carpal bone dislocation may be difficult to adequately assess and at times radiographic findings may be subtle. Radiographic abnormality may only be noted after stress (e.g., clenched fist), termed dynamic instability.¹ Dynamic instability can be seen with partial ligamentous disruption, which frequently lead to a complete injury over time. The consequences of inadequate evaluation during the initial examination or misdiagnosis may lead to progressive loss of range of motion, degenerative arthritis, along with chronic pain and disability.

For an overall understanding of ligamentous injuries of the wrist we will briefly review Mayfield’s stages of injury.⁷⁴ Specific injury patterns are mentioned as an introduction, but will be covered in greater detail below.

Mayfield described four stages of progressive carpal bone instability by experimentally loading cadaver wrists. He found that ligamentous injuries occurred in a sequential and additive fashion. Stage I injuries are associated with a tear of the scapholunate interosseous ligament and the radioscapholunate ligament. When these ligaments are torn, scapholunate dissociation or dorsal intercalated segment instability (DISI) can occur. Stage II injuries occur when there is an additional injury to the volar capitolunate ligament. This results in instability of the scaphoid and capitate. Stage III includes injury to the lunotriquetral interosseous ligament and volar lunotriquetral ligament. When these ligaments are ruptured, there is instability of the scaphoid, capitate, and triquetrum with respect to the lunate. It is at this stage that a dorsal perilunate dislocation occurs. In stage IV injuries, the dorsal radiolunate ligament is ruptured and a lunate dislocation or volar intercalated segment instability (VISI) can occur. In this case, the lunate more frequently displaces anteriorly because the volar radiolunate ligament remains intact.

Intercalated Segment Instability

This condition can be thought of as midcarpal joint collapse. The normal upright position of the lunate on the lateral radiograph is a result of the ligamentous attachments of the adjacent carpal bones. The scaphoid, by way of the scapholunate ligament, pulls the lunate into flexion, while the triquetrum, by way of the lunotriquetral ligament, pulls the lunate into extension. When the scapholunate ligament is disrupted, the unopposed force of the lunotriquetral ligament causes the lunate to tip dorsally, a condition known as DISI. On the lateral radiograph, the distal articular surface of the lunate tilts dorsally and the scaphoid bone tilts more volarly (Fig.12–40). The end result is an increase in the capitolunate angle (>30 degrees) and scapholunate angle (>60 degrees). DISI is the most common type of intercalated segment instability and may be seen with scapholunate dissociation or scaphoid fractures.

VISI is present when the lunotriquetral ligament is disrupted. The distal articular surface of the lunate now tilts volarly, creating an increased capitolunate angle (>30 degrees) and a decreased scapholunate angle (<30 degrees). On examination, there is tenderness over the lunotriquetral joint.

The presence of intercalated segment instability suggests ligamentous disruption that is best treated with reapproximation and operative repair. When this is not possible, another procedure will be required to prevent degenerative arthritis from uneven loads to the carpal joints that occur over time. In the case of disruption of the scapholunate ligament, scapholunate advanced collapse (SLAC) refers to the degenerative condition that follows.

Scapholunate Dissociation

This injury is characterized by the displacement of the scaphoid to a more vertical position in the proximal row of carpal bones. When the scapholunate ligament is ruptured, a gap between the lunate and the proximal pole of the scaphoid is produced. Rupture of the radioscapholunate ligament allows for the volar rotation of the scaphoid and is sometimes termed rotary subluxation of the scaphoid.⁷⁵ In one study, scapholunate dissociation occurred in 5% of ED patients who did not have a fracture noted on wrist radiographs.⁷⁶ This diagnosis can also be challenging in the setting of a concurrent distal radius or carpal bone fracture because of the associated pain and swelling.

Mechanism of Injury

Scapholunate dissociation often occurs as a result of forceful extension of the wrist from a fall on an outstretched hand.

Examination

Patients usually present with wrist pain and swelling. Wrist pain is accentuated at the extremes of motion. The patient may also note crepitus or a snapping sound with wrist motion. A scaphoid shift maneuver “Watson’s sign” provides a qualitative assessment of the stability of the scaphoid.⁷⁷ This maneuver should always be compared to the contralateral side. The scaphoid shift may be subtle or more dramatic. As thumb pressure is withdrawn, the scaphoid returns abruptly to its normal position, sometimes with a resounding “thunk” or “click”⁷⁸ (Fig. 12–41). Pain on performance of this test is a more reliable sign of instability than the “click.”

Imaging

These injuries are noted radiographically on the PA view as a widening of the scapholunate joint space. This joint space should always be noted in any patient with trauma to the wrist. A measurement of ≥3 mm is abnormal and is at times referred to as the “Terry Thomas sign” after a British comedian with a characteristic gap between his front teeth.^1,77,79–81 A clenched fist PA view forces the capitate head into the scapholunate joint and exposes the ligamentous laxity, making this radiograph a more sensitive means of diagnosis. When rotary subluxation of the scaphoid occurs, an additional radiographic finding on a PA view may be seen, the cortical ring sign (signet sign). This finding represents the rotation of the normally elongated scaphoid causing the distal pole to be viewed on end. On the lateral view, the scapholunate angle is noted to be >60 degrees due to the volar rotation of the scaphoid (Fig. 12–42).

Associated Injuries

Scapholunate dissociation can occur in association with perilunate or lunate dislocation or it may occur as an isolated injury or in conjunction with a scaphoid fracture or distal radius fracture.⁷⁵

Treatment

All patients with a suspected scapholunate dissociation should be placed in a thumb spica splint (Appendix A–7) or cast and referred to a hand surgeon for close follow-up. Treatment of these individuals often involves either arthroscopic or open repair of the disrupted ligament; however, optimal management should be individualized on the basis of both age and patient expectations.⁸¹

Complications

Degenerative arthritis with associated limitation in range of motion and chronic pain can be seen.

Perilunate and Lunate Dislocations

Perilunate (Stage III) and lunate dislocations (Stage IV) are often considered together, although they represent a progressive degree of injury, as described by Mayfield and outlined previously. The normal articulation of the radius, lunate, capitate, and third metacarpal makes up a straight line, this is best visualized on the lateral view of the wrist (Fig. 12–43). In a perilunate dislocation, the capitate is dislocated, usually dorsally, in relation to the lunate. With a lunate dislocation, the lunate is dislocated in the volar direction (most commonly) in relation to the distal radius and the capitate which appears in a normal position (Fig. 12–44).

Mechanism of Injury

The mechanism of injury includes excessive hyperextension, ulnar deviation, and intercarpal supination.

Examination

On physical examination, there is dorsal wrist swelling and decreased wrist motion especially upon flexion. A palpable fullness may be noted on the dorsal side of the wrist after a dorsal perilunate dislocation and on the volar surface with a volar lunate dislocation. The median nerve may be compressed in the carpal canal by the lunate. If this occurs the patient may display signs of an acute median nerve injury.

Imaging

Radiographic abnormalities will be seen on both PA and lateral wrist films. When looking at the lateral view of the wrist, draw an imaginary line down the center of the distal radius. This line should bisect directly through the midportion of the lunate, and capitate. The lateral wrist radiograph is the single most important view from which to determine correct alignment of the carpal bones. It is often helpful to rotate the image so that the wrist is viewed in the horizontal plane.

In a perilunate dislocation, the PA view reveals a capitate and lunate that overlaps. The carpal arcs are disrupted at the scapholunate and triquetrolunate joint.⁷⁵ On the lateral film, the capitate is dislocated in relation to the lunate (Fig. 12–45). With a lunate dislocation, the PA film reveals the lunate to have a triangular appearance. The lunate is displaced and tilted volarly on the lateral view (Fig. 12–46). The term “midcarpal dislocation” can be used when there is dislocation of the lunate and capitate. In this case neither bone is aligned over the center of the distal radius (Fig. 12–47). When a carpal bone fracture is also present, the term “trans” is applied to the name of the bone that is fractured, followed by the site of dislocation (Fig. 12–48).

Associated Injuries

These injuries are associated with scaphoid fractures, and less commonly capitate fractures.

Treatment

All lunate and perilunate dislocations should be immobilized with the wrist in neutral position in a volar splint and referred immediately for reduction and definitive care.

The technique for closed reduction of lunate and perilunate dislocations requires the use of either a wrist block or procedural sedation to obtain good muscle relaxation and pain control. Finger traps are used with approximately 10 lb of weight for at least 10 minutes before reduction. The reduction technique is not complicated but should be performed by someone experienced.^82,83 However, some authors prefer surgical reduction for complex perilunate dislocations.⁸²

Closed or open reduction with percutaneous fixation is indicated for an acute injury. Both perilunate and lunate dislocations usually involve either rotary subluxation of the scaphoid or commonly a scaphoid fracture.⁷⁵

Triangular Fibrocartilage Complex Tear

The term TFCC is used to describe the major ligamentous stabilizers of the DRUJ and ulnar carpal bones. Injury to this structure often occurs due to a fall but can be seen from repetitive trauma or overuse. Tenderness is localized by palpating in the hollow between the pisiform and the ulnar styloid on the ulnar border of the wrist. Dorsal tears can be diagnosed by the “supination lift test” in which the patient is asked to attempt to lift the examination table with the palm flat on the underside of the table. Eliciting pain or weakness confirms the diagnosis. Treatment is initially conservative with nonsteroidal anti-inflammatory drugs (NSAIDs), immobilization in slight flexion and ulnar deviation, followed by physical therapy. Arthroscopic repair may be required, so orthopedic referral is recommended whenever this injury is suspected.^84,85

Radiocarpal Dislocation

It is estimated that radiocarpal dislocations represents 0.2% of all dislocations (Fig. 12–49).⁸⁶ The dislocation may occur in the volar direction although dorsal dislocation is more common. These injuries often occur as a result of high-energy shear and rotational forces, because of this, a number of associated injuries can be seen, including open and closed fractures, carpal instability, tendon ruptures, and neurovascular injuries. The mechanism is thought to be forced hyperextension, pronation, and radial inclination. The injuries should be differentiated from marginal or rim fractures of the distal radius (Barton fracture) which are typically viewed as compression injuries.⁸⁶ A radiocarpal dislocation is a rare entity in the absence of an intra-articular fracture of the radius.^85,87

Prompt orthopedic consultation is recommended. After closed reduction, a dorsal dislocation should be immobilized with some wrist extension, whereas a volar dislocation is immobilized in wrist flexion. Radiocarpal dislocations have been treated successfully with closed reduction, but most cases require operative intervention.

Nerve Compression

Carpal Tunnel Syndrome (Median)

Carpal tunnel syndrome (CTS) is the most common compressive neuropathy involving the upper extremities. Acute CTS can be seen following a distal radius or carpal bone fracture/dislocation or may develop chronically as a result of repetitive strain at the wrist leading to compression of the median nerve in the carpal tunnel. In addition, a number of atraumatic conditions have been associated with the development of CTS including; thyroid disorders, pregnancy, diabetes, amyloid, lupus, Lyme disease and multiple myeloma.^62,88–90 The carpal tunnel is a confined space located between the carpal bones and the transverse carpal ligament (Fig. 12–50).

Classically, patients complain of a gradual onset of numbness or tingling along with pain in the thumb, index, and long finger. Often these complaints are bilateral and will be worse at night or with strenuous activities of the hand. At times, pain may radiate proximally to the forearm, elbow, or even shoulder but spares the little finger. Sometimes, patients will notice these complaints upon awakening. When this happens, the patient should be instructed to elevate the hand(s).

The earliest objective sensory finding in carpal tunnel syndrome is diminished vibratory sensation, tested with a 256-cycle tuning fork. More severe median nerve involvement results in abnormal two-point sensory discrimination.⁹¹

Classic physical examination findings include the Tinel and Phalen signs. Tinel test is performed by tapping the volar aspect of the wrist. A positive test is noted when the patient experiences paresthesias in the distribution of the median nerve (Fig. 12–51A). Phalen test is performed by having the patient flex their wrists for 1 minute. If paresthesias are noted in the hand over the median nerve distribution, the test is considered positive (Fig. 12–51B). A blood pressure cuff (tourniquet test) inflated to 200 mm Hg pressure for 2 minutes may also produce paresthesias in the hand and is another test for carpal tunnel syndrome.⁹² Often these tests are helpful in the bedside evaluation of the patient with suspected CTS. However, neither test is sensitive enough to identify all cases. At the current time, electrodiagnostic studies are the recognized standard for the diagnosis of CTS.^62,88–90

Conservative therapy includes avoidance of repetitive wrist and hand motions, wrist splinting, NSAIDs, and oral or local corticosteroid injection. Oral corticosteroids have been shown to be more effective than NSAIDs, current dose recommendations include prednisone 20 mg per day for 2 weeks.⁹⁰

Combined injection of corticosteroid (methylprednisolone 40 mg) and a local anesthetic agent can be both diagnostic as well as therapeutic. The best site for injection is proximal to the transverse carpal ligament, as this lowers the risk of damaging the median nerve. The needle is introduced at a 20-degree angle to the skin between the palmaris longus tendon and the flexor carpi radialis approximately 4 cm proximal to the wrist crease.⁹³ After inserting the needle beneath the transverse carpal ligament, the steroid-anesthetic solution is injected. To be certain that the needle is positioned appropriately, paresthesias in the median nerve distribution should be sought. At that time, the needle is withdrawn 1 to 2 mm and the contents of the syringe are injected.

The majority of patients respond to conservative measures although 80% recur at 1 year.⁹⁰ If a positive response is not noted, surgical decompression may be required.

Ulnar Nerve Compression

Ulnar tunnel syndrome is compression of the ulnar nerve at the level of the wrist that occurs as the nerve enters the ulnar tunnel or as the deep branch curves around the hook of the hamate in the palm. Lesions at the wrist may occur in association with repetitive trauma, arthritis, or compression from a ganglion cyst or another benign tumor. The predominant mechanism is direct compression. This condition occurs in bicyclers and others who experience repetitive compression in this area. The ulna nerve can also be subjected to external compression at the elbow (cubital tunnel syndrome). Refer to Chapter 14 for further discussion of cubital tunnel syndrome.

Patients with an ulnar nerve lesion at the wrist will experience an ulnar neuropathy similar to lesions at the elbow, with the exception of the dorsal surface of the hand. Because the cutaneous branch to this region arises proximal to the wrist, dorsal fifth digit sensation will be preserved when the ulnar nerve is compressed at the wrist.

Conservative treatment is initially recommended, which typically involves proper splinting of the involved extremity and avoidance of the inciting activity. If no improvement is noted after a period of 3 to 4 months, surgery is indicated.

Radial Nerve Compression

Radial nerve compression is less common than neuropathies involving either the median or ulna nerves.⁸⁸ Patients with radial nerve dysfunction can present with complaints of inability to extend the wrist. The most common site for compression of the radial nerve is in the axilla, most commonly after the incorrect use of crutches, and at the radial tunnel in the elbow. When compression occurs in the spiral groove of the humerus, it is called “Saturday night paralysis” because it is seen in intoxicated patients who sleep with their arms resting over the back of a chair. The resulting deficit is primarily motor, with weakness in thumb abduction (abductor pollicis longus), index finger extension (extensor indicis proprius), and wrist extension. Most of these deficits resolve spontaneously as they are secondary to a compressive neuropraxia. Treatment is a cock-up splint worn to prevent wrist drop. The reader is referred to Chapter 14 for further discussion on radial neuropathy.

Ganglion Cyst

A ganglion cyst is the most common tumor of the hand and wrist. This is a synovial cyst that originates from either a joint or the synovial lining of a tendon that has herniated (Fig. 12–52). It contains a jelly-like fluid that may become completely sealed off within the cyst or remain connected to the synovial cavity. The three most common ganglia are the dorsal wrist ganglion, volar wrist ganglion, and the flexor tendon sheath ganglion.⁹³ The dorsal wrist ganglion which arises from the scapholunate joint makes up approximately 60% to 70% of all soft-tissue tumors of the wrist.⁹⁴ These ganglia can be difficult to detect on clinical examination if small and may only be palpable with the wrist in extreme flexion. Occult dorsal wrist ganglia can produce chronic wrist pain in some patients.

The volar wrist ganglion originates from the radiocarpal joint and makes up 20% to 25% of ganglia. Ganglia arising from the flexor tendon sheath account for 10% to 15%.

A specific traumatic event will be elicited from 15% of patients. Often, only a history of chronic repetitive stress is solicited. Patients complain of a dull ache or mild pain that is noted over the ganglion. Larger ganglia are less painful than smaller ones and the pain decreases after rupture. The onset is almost always insidious, although some patients give a history of noting the “bump” over a period of a few days. A history of changing size is often obtained because of the filling and emptying into the parent synovial space. On examination, one notes a firm, usually nontender, cystic lesion that feels like a bead underneath the skin. Diagnosis is usually easy due to the frequency with which these are seen. Aspiration will disclose a jelly-like material that confirms the diagnosis when doubt exists. One must be aware of a similar lesion called a carpal boss that is seen over the base of the metacarpals of the index and long fingers, as these osseous lesions are similar in appearance. In fact, a fluid-filled sac covers some carpal bosses.

Most ganglia resolve spontaneously and do not require treatment unless symptoms such as pain are present. Treatment in the ED consists of aspiration with a large bore needle when the patient complains of symptoms. Initial treatment should include steroid injection of the dorsal capsule followed by immobilization.⁹⁵ The recurrence rate is very high with this method of treatment, and the patient must be informed of this. Reassurance is important and the patient should be informed that this lesion is not malignant.

When conservative therapy fails, operative treatment with excision of the cyst is indicated. Excision of the dorsal ganglion with a portion of the capsule at the joint is the recommended treatment of choice. In 94% of cases, a cure was achieved after operation. In approximately 65% of cases, cure was achieved after injection with a corticosteroid and/or rupture. Patients can be advised of this alternative and referred.

De Quervain Tenosynovitis

De Quervain stenosing tenosynovitis involves the abductor pollicis longus and extensor pollicis brevis in the first dorsal wrist compartment (Fig. 12–53). Patients complain of pain over the radial aspect of the wrist with radiation both proximally and distally. There is localized tenderness over the radial styloid where the pulley may look and feel thickened. On examination, the pain is reproduced when the thumb is grasped in the hand and the wrist is deviated in the ulna direction by the examiner.⁹⁶ This is commonly referred to as a positive Finkelstein test (Fig. 12–54 and Video 12–4). Although this test is sensitive and considered pathognomonic for de Quervain tenosynovitis, the accuracy of the test can be limited as pain may be elicited in patients with underlying arthritis of the wrist. In the literature, there is some confusion as the above test is at times referred to as the Eichoff maneuver.^97–99 Another description of the Finkelstein test is to have the examiner grasp the patients thumb pulling it in a longitudinal direction while applying ulnar deviation. The examiners other hand stabilizes the patient’s distal forearm on the ulnar side.^97,99.

De Quervain tenosynovitis is due to overuse or can be associated with other conditions such as rheumatoid arthritis or pregnancy.^100,101 Women are more commonly affected than men with a ratio of 10:1. Conservative treatment includes ice application to the radial styloid, NSAIDs, restriction of thumb and wrist movement with a thumb splint. (Appendix A–7). Local injection of steroids have been shown to be an effective form of therapy (Fig. 12–55 and Video 12–5). During the injection, one should see a visible swelling proximal to the extensor retinaculum; this is a guide that the needle is in the tendon sheath. Ultrasound-guided injection has been shown to improve results by confirming injection of both the sheath of the abductor pollicis longus and the extensor pollicis brevis.^100-102 After injection, place the patient in a simple thumb splint extending from the tip of the thumb to two-thirds of the way down the radial forearm. The splint should remain in place for 10 days.

Surgery is recommended if symptoms recur or persist after two injections in the course of 1 year. In the majority of cases, injection therapy is all that is needed followed by the administration of a NSAID and splinting of the thumb for a period of 7 to 10 days.