Metacarpal Bone Fractures

Metacarpal bone fractures cannot be discussed simply as a single group because of the vast differences in inherent mobility and function among them. For each, the tolerance for unreduced angulation varies. The first metacarpal is very mobile and fractures are relatively uncommon. Management includes proper reduction, placement of a thumb spica splint, and follow-up with hand surgery. The second and third metacarpals are the fixed center of the hand, and proper reduction of fractures is important for full return of function. The fourth and fifth metacarpals are more mobile and have greater ability to compensate for angular deformities. Hand surgery consultation is necessary for all metacarpal fractures; for unstable reductions; for irreducible, open, or intraarticular fractures; and for any fracture with rotational malalignment.

Metacarpal base fractures are uncommon and usually of little significance.² The exception is at the base of the fifth metacarpal bone, where there can be associated subluxation of the metacarpal-hamate joint. The injured hand should be immobilized in an ulnar gutter splint and scheduled for referral to hand surgery.

Bennett/Reverse Bennett and Rolando Fractures

A Bennett fracture is a fracture of the proximal first metacarpal bone (Fig. 89.1). The classic mechanism is an axial load onto a flexed and adducted thumb. For example, a football quarterback strikes the helmet of an opposing player after releasing a throw. In this avulsion injury, the strong abductor pollicis longus muscle fractures the bone at the point of its insertion at the ulnar aspect of the first metacarpal bone. This causes displacement of a bony fragment, which can be seen on a plain film radiograph. It is usually an unstable fracture, and ED management should consist of referral to a hand surgeon and immobilization in a thumb spica splint. Potential long-term morbidity includes malunion, decreased function, and significant arthritis.

Fig. 89.1 Bennett fracture (arrows).

(From Mettler Jr FA. Essentials of radiology. 2nd ed. Philadelphia: Saunders; 2004.)

The same injury pattern and mechanism of injury can also occur in the fifth metacarpal bone and is called a reverse Bennett fracture, which is as unstable as a Bennett fracture because of the traction exerted by the extensor carpi ulnaris muscle on the distal aspect of the fifth metacarpal. Traction tends to pull the distal segment ulnarly. Closed reduction with ulnar gutter splinting may be attempted, but any articular incongruity must be recognized and referred on an emergency basis to a hand surgeon for potential immediate operative repair.

A Rolando fracture is similar to a Bennett fracture; however, it is comminuted and by definition extends into the joint space. ED management is identical to that for a Bennett fracture.

Boxer’s Fracture

Although many people refer to any fracture of the fifth metacarpal as a boxer’s fracture, the specific injury is a fracture through the neck of the bone (Fig. 89.2). This injury is most frequently seen when a solid object is forcefully struck with a closed fist. True boxer’s fractures may carry significant morbidity because in addition to being an unstable fracture, the injury often has a rotational component. If allowed to heal in this position, the hand will be deformed and weakened.

Fig. 89.2 Boxer’s fracture (arrow).

(From Mettler Jr FA. Essentials of radiology. 2nd ed. Philadelphia: Saunders; 2004.)

ED management consists of an attempt at closed reduction and placement of a dorsal-volar splint. Regardless of the type of splint used, at a minimum the fourth and fifth MCP joints should be splinted at 90 degrees of flexion. Because of the instability of this fracture, all patients should be referred to a hand surgeon and warned of the significant likelihood that the injury will require operative management.

Proximal and Middle Phalanx Fractures

Proximal and middle phalanx fractures are managed similarly. The degree of instability depends on the nature of the fracture. Transverse and spiral fractures have greater instability than simple fractures do and are therefore more likely to require percutaneous fixation. It is important to keep in mind that rotational deformity cannot be tolerated. When the hand is held in a relaxed fist, the fingers should all point to the scaphoid region. Visible deviation from this plane suggests a rotational deformity of greater than 10%. All nondisplaced proximal and middle phalanx fractures should be splinted in the ED and referred for outpatient follow-up. Rotated, transverse, displaced, or intraarticular fractures should be reduced and splinted, and contemporaneous hand surgery consultation should be obtained.

Distal Phalanx Fractures

The most common distal phalanx fracture is a tuft fracture, and nail bed injuries are the most common complication of this fracture.² There is some controversy regarding the need to repair nail bed injuries; however, most authors recommend performing trephination only for nail bed hematomas involving 30% to 50% or greater of the nail bed surface. When the nail bed is involved, tuft fractures are considered open fractures. Although some physicians prescribe antibiotics empirically, evidence suggests that prophylactic antibiotics are not indicated.⁴ Proximal distal phalanx fractures are often unstable and require hand surgeon referral for percutaneous wire placement. An attempt to reduce any rotational deformity or angulation should be made before splinting. Splinting should isolate the DIP joint alone.

de Quervain Tenosynovitis

de Quervain tenosynovitis is an overuse injury of the thumb. The classic example of the mechanism is a fly fisherman who repetitively collects the line after each cast by using the thumb and index finger to grasp the line, thereby resulting in inflammation of the abductor pollicis longus and extensor pollicis brevis tendons. The diagnosis is made clinically, and a positive Finkelstein test is said to be pathognomonic. The Finkelstein test is considered positive when pain is elicited with passive ulnar deviation of a closed fist.

It is important to note that patients with this condition may complain of pain on palpation of the anatomic snuffbox because the aforementioned tendons form the radial border of that structure. If the history is suggestive of a possible scaphoid injury, radiography should be performed and a thumb spica splint applied. Treatment of simple de Quervain tenosynovitis consists of rest, application of ice, and nonsteroidal antiinflammatory drugs (NSAIDs); more severe cases may require splinting to rest the injured joint.

Gamekeeper’s/Skier’s Thumb

Gamekeeper’s thumb is also called skier’s thumb. The mechanism is hyperextension of an abducted thumb causing injury to the ulnar collateral ligament, and it is often associated with an avulsion fracture (Fig. 89.3). Historically, old-world gamekeepers sustained this injury while dispatching wounded birds during hunts. Today, this injury often occurs when a skier falls while grasping the ski pole.

Fig. 89.3 Gamekeeper’s thumb (arrow).

(From Perron AD, Brady WJ. Evaluation and management of the high-risk orthopedic emergency. Emerg Med Clin North Am 2003;21:159–204.)

Physical examination will be remarkable for tenderness at the ulnar collateral ligament, laxity at the MCP joint, and inability to actively oppose the thumb (Fig. 89.4). Most ulnar collateral ligament ruptures occur at the distal attachment. If the injured joint demonstrates 40 degrees of radial angulation during stressing, complete ligament rupture should be assumed. An associated avulsion fracture may be present. Treatment consists of immobilization in a thumb spica splint, NSAIDs, and referral to a hand surgeon for open reduction with internal fixation.

Fig. 89.4 Testing for ulnar collateral ligament integrity.

(From Patel D, Dean C, Baker R. The hand in sports: update on clinical anatomy and physical examination. Prim Care 2005;32:71–89.)

The initial examination may be compromised secondary to pain and spasm. In these cases, the most prudent course of action is immobilization in a thumb spica splint and referral for reevaluation.

Jersey Finger

Jersey finger is an injury often associated with tackling sports (Fig. 89.5). The injury itself consists of disruption of the flexor digitorum profundus joint, which is responsible for flexion of the digit at the DIP joint. It occurs when a digit (often the second digit) is forced into extension while actively being flexed, as might occur when grabbing an opponent’s jersey during a tackle.

Fig. 89.5 Jersey finger.

(From Perron AD, Brady WJ. Evaluation and management of the high-risk orthopedic emergency. Emerg Med Clin North Am 2003;21:159–204.)

On physical examination an injured patient will not be able to flex the digit at the DIP joint when the PIP joint is held (by the examiner) in extension. Examining the DIP joint without holding the PIP joint may result in a false-negative test result because of contribution from the lateral bands. The patient may complain of pain more proximally along the flexor tendon sheath or even in the palm because the ruptured flexor digitorum profundus tendon will retract. It is therefore imperative to challenge the distal joint despite only proximal pain. With full disruption the best outcomes depend on early surgical repair, and all patients should be scheduled for hand surgeon referral.

Mallet Finger

Mallet finger is in many ways the functional opposite of jersey finger. In mallet finger the distal extensor tendon is ruptured (Fig. 89.6). It often occurs when the distal phalanx of a finger (or thumb) is forced into flexion while being actively extended. In sports the middle finger is most often affected because of its length, and it occurs when the finger is jammed, as when attempting to catch a ball.

Fig. 89.6 Mallet finger.

(From Perron AD, Brady WJ. Evaluation and management of the high-risk orthopedic emergency. Emerg Med Clin North Am 2003;21:159–204.)

Because this injury is often painless, it is not always manifested immediately. Physical examination is remarkable for the inability to extend the finger at the affected DIP joint. Radiographs may demonstrate an avulsion fracture. Treatment consists of immobilization by splinting the DIP in full extension, which allows full range of motion at the PIP joint. The patient should be referred to a hand surgeon for follow-up. Most mallet fingers are treated nonoperatively; however, those with large avulsion fracture fragments may require operative management.

Digital Dislocations

Dislocation of the DIP joint is a rare injury, but when it does occur, it most commonly dislocates in the dorsal direction after direct force on the finger pad. Relocation is best accomplished after a digital block with traction longitudinally and pressure directing the proximal aspect of the distal phalanx back to correct alignment. After relocation, the entire digit is splinted in extension. Some injuries are nonreducible and require operative repair because the volar plate or profundus tendon (or both) may occupy the joint space. Any indication of joint involvement should prompt referral to a hand surgeon.

PIP joint dislocations result in more complications than do DIP joint dislocations. The complex biomechanics of the joint adds a degree of intricacy that often results in the need for operative repair. The volar plate may be injured with dorsal dislocations, and the lateral collateral ligaments may be injured with ulnar or radial dislocations. It is important to assess any relocated joint for stability to better rule out the potential for ligament or volar plate injury. Patients with an irreducible or unstable joint should be referred to a hand surgeon for operative repair. If stable, the joint should be splinted in 30 degrees of flexion for 2 to 4 weeks.

MCP joint dislocations are seen less commonly than PIP dislocations but have a similar rate of complications. Dislocations may be partial or complete and may involve the volar plate. Care should be taken during the examination to not convert a partial dislocation to a complete dislocation. Injury most commonly occurs as a hyperextension mechanism. With complete dislocations and volar plate involvement, relocation is often impossible because the volar plate may become entrapped in the joint space. For the best chance of relocation, the wrist should be placed in full flexion to relieve all flexor tendon tension and exert longitudinal and volar force. The MCP joint should be splinted in full flexion.

Extensor Tendon Injuries

Open wounds on the dorsum of the hand and digits should trigger suspicion for extensor tendon injury. The Verdan extensor tendon injury classification system uses eight anatomic zones to direct treatment (Table 89.1).

Table 89.1 Verdan Classification of Extensor Tendon Injuries with Appropriate Disposition

ED, Emergency department.

Data from Verdan CE. Primary and secondary repair of flexor and extensor tendon injuries. In: Flynn JE, editor. Hand surgery. 2nd ed. Baltimore: Williams & Wilkins; 1975.

Treatment of extensor tendon injuries should usually be coordinated with a hand surgeon. Data on suture repair of partial tendon lacerations are lacking, and current treatment is based on flexor tendon treatment. Conservative treatment of injuries involving less than 50% of a cross-sectional area has been proposed.

Injuries to zones I and II occur with axial loading onto a fully extended DIP joint, which forces the DIP joint into flexion and disrupts the distal aspect of the extensor tendon. This creates a mallet injury, as described previously.

Zone III injuries are caused either by axial loading and forced flexion of the PIP joint or by direct trauma to the PIP joint. These injuries should be splinted with the joint in extension, and the patient should be referred to a hand surgeon. With complete disruption of the central slip, the lateral bands slide toward the volar surface of the digit, which causes the extensor tendons to act as flexors. Untreated injuries lead to a boutonnière deformity in which the PIP is flexed and the DIP is hyperextended.

Most zone IV injuries are caused by direct trauma. Open injuries may be treated primarily as in zone IV; by definition, no joint involvement is present. Closed injuries should be splinted with extension of the PIP joint. The extensor tendons of the phalanx are broad and flat, which allows easier primary repair.

“Fight bite” must be considered in all patients with zone V ligament injuries. Patients with open injuries should be referred to a hand surgeon for primary repair. Closed injuries can be treated by splinting the MCP joint in extension while allowing free range of motion of the PIP joint.

Zone VI injuries are usually superficial and easily repaired by the EP. Suture material should be strong, such as braided nylon, and the lacerated tendon completely apposed. After closure, the wrist should be splinted in 30 degrees of extension and the MCP joint in 15 degrees of flexion, and the PIP joint should be free. The patient should be referred to a specialist for dynamic splinting.

Zone VII and VIII injuries often involve the extensor retinaculum, and the patient should be scheduled for referral to a hand surgeon for primary closure. The affected tendon often retracts into the forearm, thus complicating the repair. Because of the density of associated anatomic structures, operative survey of the injury to identify additional injuries is indicated.

Flexor Tendon Injuries

All patients with open flexor tendon injuries should be referred to a hand surgeon for emergency evaluation (Table 89.2). However, some knowledge of the nomenclature and prognoses associated with flexor tendon injuries will aid the EP in conversations with both the consultant and the patient.

Table 89.2 Verdan Classification of Flexor Tendon Injuries with Appropriate Disposition

Data from Verdan CE. Primary and secondary repair of flexor and extensor tendon injuries. In: Flynn JE, editor. Hand surgery. 2nd ed. Baltimore: Williams & Wilkins; 1975.

Repair of complete lacerations within 24 hours is most commonly recommended. Operative repair is usually limited to injuries involving greater than 50% of a cross-sectional area. Injuries involving less than 50% are frequently treated conservatively with splinting. Newer data suggest that conservative management is adequate for injuries occupying less than 75% of a cross-sectional area; however, this decision should be deferred to the consulting hand surgeon.¹ When splinting flexor tendon injuries, the wrist should be placed in 30 degrees of flexion, MCP joint injuries in 70 degrees of flexion, and DIP or PIP joint injuries in 10 degrees of flexion. Classification of flexor tendon injuries is based on anatomic location, treatment, and prognosis. All patients with flexor tendon injuries should be referred to a hand surgeon for operative exploration and repair.

Scaphoid Fractures

The scaphoid is the most commonly injured carpal bone. A high index of suspicion is needed when considering this injury because plain film findings are often subtle or even absent (a dedicated scaphoid view will increase plain film sensitivity). The mechanism of injury is most often a fall onto an outstretched hand.

Morbidity is high with this injury because the bone is anatomically predisposed to avascular necrosis and nonunion. The blood supply to the scaphoid originates from the radial and palmar arteries and flows from distal to proximal. The most proximal aspect of the scaphoid receives blood only from this distal to proximal flow, and if this flow is interrupted by a fracture, the risk for avascular necrosis and nonunion is high. For this reason all patients with a traumatic mechanism and scaphoid tenderness, as assessed by palpation of the anatomic snuffbox or pain with axial loading of the thumb, should be treated with a thumb spica splint and referred for follow-up. Roughly 15% of these patients will have a scaphoid fracture despite unrevealing plain films.⁵

Triquetrum Fractures

Triquetrum fractures are less common than scaphoid fractures but frequently have a similar mechanism of hyperextension. Most often the fracture is secondary to avulsion with an avulsion fragment noted at the dorsal aspect of the triquetrum. This is best seen on a lateral plain film projection. The prognosis is better than with scaphoid fractures because avascular necrosis is not a common occurrence with these injuries.

Occasionally, triquetrum body fractures can be seen; in this case the EP should look for associated lunate or perilunate dislocations. The wrist should be splinted and the patient referred to a hand surgeon for follow-up.

Scapholunate Dislocation

Scapholunate dislocation is the most common of these injuries and occurs with the least amount of force. It can be diagnosed on plain film radiography. Scapholunate dislocation results in a classic radiologic finding—the Terry-Thomas sign (Fig 89.7). Terry-Thomas was a 20th-century British comedian who possessed a noticeable gap between his two front teeth, reminiscent of the wide space (2 mm when measured on an anteroposterior view) seen between the scaphoid and lunate bones when they are dislocated.³ Stress views accentuate this finding. Additionally, the scaphoid may twist on its axis and cause a ringlike shadow known as the signet ring sign. This artifact is caused by the x-rays traveling longitudinally down the twisted scaphoid, unlike the normal crosswise orientation. Mayfield et al. classified this injury as a stage I injury.⁶

Fig. 89.7 Scapholunate dislocation.

A, Terry-Thomas sign (arrows). B, Normal wrist. L, Lunate; N, navicular.

(From Mettler Jr FA. Essentials of radiology. 2nd ed. Philadelphia: Saunders; 2004.)

Perilunate Dislocation

Stage II injury is associated with progressively more force (e.g., an automobile accident versus a slip and fall) and results in perilunate dislocation (Fig. 89.8). Perilunate dislocations may be a difficult concept because there is no “perilunate” bone. Perilunate dislocation is a disruption of the ligamentous structures around (“peri”) the lunate bone. One of these structures is the capitate, which most often dislocates dorsally. Perilunate dislocation may perhaps better be called capitate dislocation; however, perilunate dislocation is actually a more accurate description of the stepwise disease process as outlined by Mayfield et al.⁶ Dislocation of the capitate can be associated with a scaphoid fracture. The EP should be diligent in assessing for one in the setting of the other. Perilunate dislocation is frequently overlooked despite the classic plain film finding of the capitate and the remainder of the distal part of the hand lying dorsal to the lunate on the lateral projection.

Fig. 89.8 Perilunate dislocation.

C, Capitate; L, lunate; R, radius; U, ulna.

(From Mettler Jr FA. Essentials of radiology. 2nd ed. Philadelphia: Saunders; 2004.)

Triquetrum Dislocation

Stage III injury involves dislocation of the triquetrum but is difficult to differentiate radiographically from stage II perilunate dislocation.

Lunate Dislocation

Stage IV injury is defined by the presence of a lunate dislocation. It is a complete disruption of the ligamentous structures of the wrist. In stage I the scaphoid dislocates from the lunate, in stages II and III the capitate and triquetrum dislocate from the lunate, and in stage IV the lunate dislocates from its articulation with the distal end of the radius. The dislocated capitate, which lies dorsal to the lunate, will often collapse onto the distal end of the radius as a result of muscular spasm because the lunate is no longer present to prevent such spasm.

The result is a distal radius and capitate pseudoarticulation, with the lunate lying palmar to the “new” wrist articulation. This is best viewed on a lateral plain film projection and causes the “spilled teacup” sign (Fig. 89.9). When teaching this concept, the author has asked students to imagine a watermelon seed being squeezed between two fingers and then popping forward with force. This is essentially what happens to the lunate as it is “squeezed” by the radius and distal wrist structures, including the capitate, in an extreme hyperextension mechanism. Lunate dislocation often compresses the carpal tunnel and can cause median neuropathy.

Fig. 89.9 Lunate dislocation: spilled teacup sign.

C, Capitate; L, lunate; R, radius; U, ulna.

(From Mettler Jr FA. Essentials of radiology. 2nd ed. Philadelphia: Saunders; 2004.)

Plain film radiography is in general adequate to diagnose carpal bone dislocations, although computed tomography can be helpful in ambiguous cases. The EP may attempt closed reduction; however, many of these injuries are unstable. All injuries should be splinted in a long arm splint and patients should be referred to a hand surgeon. Many of these injuries will require internal fixation.