INCIDENCE

The most common upper extremity fractures are those of the metacarpals and phalanges. In a series of 4303 patients presenting to the emergency room with fractures, 19% had hand fractures.¹ The phalanges were most commonly fractured. Males between the ages of 15 and 35 were most commonly injured. Fractures of the little finger ray were most common.

Hove, in a series of 1000 consecutive patients, found that metacarpals, phalanges, and carpal bones accounted for 36%, 46%, and 18% of the fractures, respectively.² Chung and Spilson analyzed data from the 1998 National Hospital Ambulatory Medical Care Survey and estimated that in 1998, there were more than 600,000 metacarpal and phalangeal fractures in the United States.³

Fractures in children follow different patterns in various age groups because of differing mechanisms of injury. In a review of 242 hand fractures, Mahabir et al. found that 75% of injuries were in males, the mean age being 11 years.⁴ The incidence of fractures was very low in the very young, rose sharply at age 9, and peaked at 12 years. Forty percent were epiphyseal fractures, predominantly Salter-Harris II. The fifth metacarpal was the most frequently fractured bone.

The incidence of hand injuries in polytrauma was studied by Schaller and Geldmacher.⁵ They noted a 20% incidence of associated hand injuries, 75% of which were closed fractures. Ninety-three percent were involved in motor vehicle accidents.

MECHANISM OF INJURY

Chung and Spilson described the cause of injury in hand and forearm fractures.³ Forty-seven percent of injuries were due to falls, while 15% were due to being struck by a person or object. Ten percent were due to vehicular accidents. Other causes included being caught between objects, accidents involving machines or tools, injury due to another person, and nontraffic motor vehicle accidents.

De Jonge et al. studied the incidence and etiology of 6857 phalangeal fractures.⁶ They found that falls were responsible for most injuries in patients 70 years or older, while sports were the main cause in the age group 10–29 years. The highest incidence was in males aged 40–70 years, and the cause was machinery. Over 45% of hand fractures in children occurred either during sports or in a fight.

DIAGNOSIS

Management of hand injuries requires a good understanding of hand anatomy and biomechanics. The individual needs of the patient need to be taken into account before devising a treatment plan. A detailed history needs to be obtained. Key points to be elicited are noted in Table 2.

Table 2 History in Hand Injuries

Examination of the hand should assess deformity, tenderness, instability, sensation, and vascularity of the finger. The condition of the skin and soft tissues should be evaluated, including an assessment for injury to the tendons. It is particularly important to assess the finger cascade. On flexion of the fingers to make a fist, the tips of the fingers should converge toward the scaphoid. Scissoring of the fingers indicates rotational malalignment. Evaluation of stability is necessary to rule out ligamentous injury. This is done after administration of local anesthetic to prevent pain and reflex muscle spasm. The congruity of the joint is assessed during active motion and passive stress. Partial injuries can be treated by immobilization, while complete tears may require surgical repair.

Three views are necessary for adequate radiologic evaluation: anteroposterior, lateral (with the fingers fanned out), and an oblique view. The lateral view obtained in this manner, however, shows, at best, one finger in a true lateral position. Hence, it is better to get lateral views of individual fingers. Very rarely, special views of the hand are necessary to assess certain injuries. Occasionally, stress views of joints are used—for example, to evaluate collateral ligament injuries of the thumb metacarpophalangeal joint.

METACARPAL FRACTURES

The metacarpals are structurally divided into the head, neck, shaft, and base. The metacarpal head articulates with the base of the proximal phalanx. The collateral ligaments between the metacarpal and phalanx arise in an eccentric position. Hence, these ligaments are stretched in flexion and lax in extension, and the joint is stable in flexion (Figure 1). The thumb metacarpal and fourth and fifth metacarpals are mobile. Because of its unique anatomy, thumb fractures are dealt with separately. Common metacarpal fracture patterns are illustrated in Figure 2.

Figure 1 Metacarpophalangeal joint anatomy. The collateral ligaments arise in an eccentric fashion on the metacarpal head, resulting in a stable position in flexion.

Figure 2 Common fracture patterns. (A) Transverse. (B) Spiral. (C) Comminuted. (D) Neck. (E) Intra-articular.

Metacarpal Shaft Fractures

Transverse fractures are caused by axial loading or direct blows. Because of the pull of the interossei, the fracture angulates dorsally. Patients can accept some angulation of the fourth and fifth metacarpals because of mobility. Greater than 30-degree angulations of the fifth metacarpal, 20 degrees in the fourth metacarpal, and any angulation in the second and third metacarpals require reduction. Oblique and spiral fractures, on the other hand, cause rotational malalignment. This is poorly tolerated, because the fingers overlap each other when the fingers are flexed. Transverse fractures are inherently stable, while spiral and oblique fractures are not.

Most metacarpal shaft fractures can be managed nonoperatively. The fracture is reduced if needed, and the hand is immobilized in the so-called safe position, with the wrist in 30–40 degrees of extension, the metacarpophalangeal joints in 80–90 degrees of flexion, and the interphalangeal joints in extension. Immobilization is maintained for 3–4 weeks and is followed by active mobilization.

Open reduction is indicated when the fracture is malaligned or unstable. Open fractures and those with associated soft tissue injuries are also best treated by open reduction. This permits earlier mobilization to prevent stiffness. With multiple metacarpal fractures, the stabilizing influence of the adjacent metacarpals is lost, and such fractures may need open reduction and internal fixation. Various techniques are available to stabilize fractures. Spiral or long oblique fractures can be stabilized by lag screws (Figure 3). The length of the fracture line should be at least twice the diameter of the bone. The proximal hole is overdrilled to a diameter wider than the thread of the screw. As the screw is tightened and the threads grip the distal fragment, interfragmentary compression is achieved.

Figure 3 (A) Metacarpal shaft fracture sustained in a fist fight. (B) Fixation with three lag screws.

Kirschner wires can be used to stabilize shaft fractures. Percutaneous insertion involves minimal soft tissue dissection; however, the stabilization is not rigid, and patients need to be splinted. Rarely, pin tract infections can complicate treatment. Multiple wires are usually placed to avoid rotation of fragments (Figure 4).

Figure 4 (A) Metacarpal shaft fracture sustained in a fist fight. (B) Fixation with Kirschner wires.

Fixation with plates and screws provides rigid fixation. This permits early mobilization, which can be critical to the successful rehabilitation of patients with concomitant tendon or other soft tissue injuries that are adversely affected by scar and adhesion formation. Plate fixation itself requires significant tissue dissection. This can result in adhesions, reduced tissue glide, and suboptimal functional outcomes. Again, early mobilization is essential to optimize functional outcomes. Plate fixation is particularly useful in the treatment of complications such as nonunion or malunion requiring corrective osteotomies.

Metacarpal Neck Fractures

The most commonly encountered fracture is that of the fifth metacarpal neck. These fractures are known as “boxer’s fractures” and, as the name implies, are caused by impact of a clenched fist against a rigid surface, which is frequently the face of another individual or a wall. Impact of the closed fist against a tooth can lead to a serious human bite infection. The tooth can penetrate the joint space. As the finger is extended, the extensor tendon glides proximally and closes the joint space. This provides a good environment for growth of anaerobic bacteria. These bite injuries are commonly associated with metacarpal head fractures. If not treated or inadequately treated, these injuries can lead to severe infections and loss of function. Since these patients tend to be noncompliant and present late, they may need to be admitted to the hospital for debridement, open joint drainage, irrigation, and intravenous antibiotics. Staphylococcus aureus and Streptococci are the most common organisms cultured from these infections. Other organisms such as Eikanella corrodens, Neisseria, and Clostridia have also been cultured.

Metacarpal neck fractures angulate dorsally because of the pull of the intrinsic muscles. The fourth and fifth metacarpals have more mobility at the carpometacarpal joints, and hence angulation in the ulnar metacarpals is better tolerated from the functional standpoint. Patients may complain about the resultant deformity—a loss of prominence of the knuckle—and also about feeling a mass in the clenched fist.

Closed reduction of metacarpal neck fractures is achieved by the Jahss maneuver⁸ (Figure 5). Local anesthesia with a hematoma block is administered. Traction is applied and the fracture is disimpacted. The metacarpophalangeal and interphalangeal joints are flexed to 90 degrees. This relaxes the intrinsics and tightens the collateral ligaments. An upward push on the proximal phalanx transmits force to the distal fragment to achieve reduction. Reduction is confirmed by radiology. The hand is immobilized in an ulnar gutter splint. If the fracture is more than 7–10 days old, closed reduction is usually not possible.

Figure 5 Jahss maneuver.

Persistent dorsal angulation of more than 30–40 degrees of the ring and little finger metacarpals, more than 10–15 degrees in the index and long finger metacarpals, and any rotational malalignment require operative intervention. Percutaneous insertion of Kirschner pins usually suffices. On occasion, open reduction and pinning, or plate application is necessary.⁶

Thumb Metacarpal Fractures

Thumb metacarpal head, neck, and shaft fractures are treated as outlined previously (Figure 6). Fractures of the metacarpal base are important because loss of the carpometacarpal joint integrity can severely compromise hand function. Two patterns of injury are notable: Bennett’s fracture and Rolando fracture.⁶

Figure 6 (A) Transverse fracture of thumb metacarpal base following a crush injury. (B) Fixation with a condylar plate.

Bennett’s Fracture

Bennett’s fracture is an intra-articular fracture of the base of the thumb metacarpal (Figure 7). The smaller ulnar fragment remains attached to the trapezium by the volar oblique ligament, and the shaft is displaced by the pull of the adductor pollicis and abductor pollicis muscles. It is difficult to maintain reduction in a cast, so these fractures require operative intervention. Once reduced, the reduction is maintained by passing a Kirschner wire through the metacarpal shaft into the trapezium or the second metacarpal. It is not necessary to include the small fragment. If reduction is not possible by the closed technique, open reduction is necessary.

Figure 7 Bennet fracture following a fall from a motorcycle.

PHALANGEAL FRACTURES

Proximal and Middle Phalangeal Fractures

Stable nondisplaced shaft fractures and those that are stable after reduction are immobilized with malleable aluminum splints and a short arm splint in the safe position. The finger can be “Buddy taped” to an adjacent noninjured finger to prevent rotational malalignment. Mobilization should be initiated early to prevent stiffness. Immobilization for more than 3 weeks is seldom necessary. Unstable fractures require pinning (Figure 8). Plate and screw application in the fingers can potentially compromise tendon function and soft tissue coverage.

Figure 8 (A) Proximal phalanx fracture following a motorcycle accident, and (B) following pinning.

Condylar fractures are serious injuries with poor outcomes. They require accurate reduction and fixation.

DISLOCATIONS

Proximal Interphalangeal Joint Dislocation

Dislocation of the proximal interphalangeal (PIP) joint is the most common ligamentous injury in the hand. These can be dorsal, volar, or lateral (Figure 9).

Figure 9 (A) Interphalangeal joint dislocation. (B) Post reduction.

Dorsal dislocations are usually caused by hyperextension combined with longitudinal compression. Sometimes this can be associated with a fracture to the volar lip of the middle phalanx. Rarely, the volar plate can rupture and get interposed between the proximal and middle phalanges, producing an irreducible dislocation. Closed reduction is performed by traction and palmar flexion while applying pressure to the base of the middle phalanx. If after reduction of the dislocation, the joint is stable, the finger is splinted. Motion in a dorsal blocking splint is initiated in 1–2 weeks. Protected-range-of-motion exercises, by buddy taping the finger to an adjacent finger, are initiated at 3 weeks, and unprotected motion is started at 8 weeks. In fracture dislocations, if the fracture involves less than 40% of the articular surface, the joint is usually stable and can be treated as outlined previously. Larger fractures require pinning or dynamic skeletal traction, especially for pilon fractures.

Volar dislocations are unusual. These can be true volar dislocations or volar rotatory subluxations. Volar dislocations are usually associated with rupture of the central slip of the extensor tendon. After reduction, this should be treated with immobilization in full extension for 4–6 weeks. Failure to treat the central slip rupture results in a Boutonniere deformity. Volar rotatory dislocations are reduced by applying traction on the middle phalynx with the PIP flexed. Rotatory motion can reduce the dislocation. Open reduction is indicated if the dislocation is irreducible.

Lateral dislocations occur with rupture of a collateral ligament and a volar plate tear. Following reduction, the finger should be buddy taped and protected range of motion initiated.

METACARPOPHALANGEAL JOINTS

These are usually dorsal dislocations caused by hyperextension of the joint. They are divided into simple subluxations and complex dislocations. In simple subluxations, the volar plate is draped over the metacarpal head, and the proximal phalanx is in hyperextension over the metacarpal head. Simple dislocations are reduced by flexing the wrist while applying traction and flexing the MP joint. Following reduction, a dorsal extension block splint is applied (Figure 10).

Figure 10 (A) Simple metacarpophalangeal joint dislocation following a fist fight. (B) Post reduction.

In complex dislocations, the metacarpal head protrudes volarly between the lumbrical and flexor tendon. The volar plate is folded and entrapped between the two articular surfaces. Hyperextension of a simple subluxation can pull the volar plate further into the joint, entrapping it and converting it into a complex dislocation. Complex dislocations present with the MP joint in slight extension, palpable metacarpal head in the palm, and dimpling of the skin from pull on the periosteal dermal attachments. X-rays, especially of the first metacarpophalangeal joint, may show the sesamoid bones in the joint space, indicating volar plate entrapment. Complex dislocations require open reduction.

Forced lateral deviation of the fingers can lead to rupture of the collateral ligaments. Patients often present late. Tenderness along the collateral ligament and instability and pain on lateral stressing are noted on clinical examination. Immobilization followed by protected motion by buddy taping is used. In complete tears with significant instability, surgical repair is indicated.

COMPLICATIONS

Both undertreatment and overtreatment of hand fractures and dislocations can lead to complications. The most common complication is stiffness, and its prevention is of paramount importance in the restoration of hand function. Joint contractures can result from prolonged immobilization. The safe position must be utilized, whenever feasible. Scarring can result in tendon adhesions and entrapment of nerves, resulting in poor function. Stabilization of fractures and early protected motion are essential. Clinical healing precedes radiologic union. On the other hand, inadequate immobilization can lead to malunion, or nonunion. Malunion and nonunion may require operative intervention to correct. Corrective osteotomies and internal fixation are utilized to treat malunion. Nonunions may require bone grafting (Figure 11). Infection can be seen in open fractures and are more likely in human bite injuries. These injuries require antibiotic prophylaxis after adequate debridement.

Figure 11 (A) Open, heavily contaminated fracture following an industrial accident, a crush injury with a plastic cutting device. (B) Following operative debridement and removal of devitalized bone, external fixator applied to maintain bone length and facilitate wound care. (C) Iliac crest bone graft applied following soft tissue healing. (D) Consolidated bone following removal of external fixator.

Operative treatment of fractures can convert a previously closed fracture into an open fracture, hence risking infection. Injury to tendons, nerves, or vessels is also possible. Implants can fail with breakage of plates and screws.