The capitate is an elongated carpal bone that has a large proximal articular head that contacts the lunate; the midportion is the neck and the distal end is the body. Capitate fractures most often occur in the neck, and usually occur in conjunction with a scaphoid fracture. This association of scaphoid and capitate fractures is called the "scaphocapitate syndrome." Isolated capitate fractures are rare. These injuries result from forceful dorsiflexion of the hand with impact on the radial side. The scaphoid is fractured first, followed by the capitate through its neck. This can continue around the lunate creating other so-called arc fractures, and eventually a perilunate or lunate dislocation. Capitate fractures also share the same legacy of potential avascular necrosis of the proximal fracture segment. Like the scaphoid and lunate, the capitate's blood supply enters through the distal end.
Physical examination will reveal diffuse swelling and tenderness over the capitate. The capitate neck fractures are best seen on the lateral radiograph. The head of the capitate should be carefully noted because it can rotate as much as 180 degrees. Unfortunately, capitate fractures are most often overlooked because the accompanying scaphoid fracture or perilunate/lunate dislocation overshadows it. Most of these fractures are displaced, and require closed or open reduction with internal fixation. Avascular necrosis, delayed union, nonunion, and malunion may complicate them.
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