History and Physical Examination
Injuries to metacarpal base
Many fractures and fracture dislocations of the metacarpal base are caused by substantial axial loads and frequently are associated with other injuries. Diagnosis usually is directed by the history and clinical examination. Tenderness, swelling, and loss of motion are common, as with any fracture or dislocation. Additionally, dorsal carpometacarpal (CMC) joint dislocations may be associated with marked swelling and sometimes a palpable stepoff. Stress of the fifth metacarpal reveals instability in cases of intra-articular fractures of that metacarpal base.
Fractures of metacarpal shaft and neck
Problems associated with metacarpal shaft fractures relate to shortening, rotation, and dorsal apex angulation. Of these, malrotation is the most critical. Minor rotational deformities can cause the fingers to overlap when the hand is made into a fist.
Rotational abnormalities are best judged clinically by comparing the injured and uninjured digits through a full range of motion (ROM). With flexion, each digit should point toward the scaphoid tuberosity. The plane of the nail should be similar between the injured digit and the contralateral corresponding finger when evaluated in an intrinsic plus position.
Like shaft fractures, metacarpal neck fractures usually are easily diagnosed by localized tenderness and swelling with loss of dorsal knuckle contour. The ring and small metacarpals are most commonly fractured.
Injuries to metacarpal head
Pain, swelling, and loss of motion are the key clinical signs of injury to the metacarpophalangeal (MCP) joint. Crepitus may be present with motion in intra-articular injuries.
Metacarpophalangeal dislocations
Dorsal dislocations are readily identified by a hyperextension posture of the digit with loss of joint flexion. Dimpling of the skin dorsally may also be observed. (See the image below.)
Complex 2nd metacarpophalangeal (MCP) dislocation in skeletally immature patient; note position of finger and dimpling of skin on volar hand.
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AP radiograph of displaced 4th and 5th metacarpal fractures.
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Lateral radiograph of displaced 4th and 5th metacarpal fractures.
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Oblique radiograph of 4th and 5th metacarpal fractures.
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AP radiograph of 4th and 5th metacarpal fractures following intramedullary pinning.
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Lateral radiograph of 4th and 5th metacarpals following intramedullary pinning.
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Complex 2nd metacarpophalangeal (MCP) dislocation in skeletally immature patient; note position of finger and dimpling of skin on volar hand.
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Radiograph of complex 2nd metacarpophalangeal (MCP) dislocation in skeletally immature patient (same patient as in Image 6).
