Closed crush injury of the metacarpophalangeal joint.

Closed crush injuries from direct blows to the dorsum of the hand may produce significant metacarpophalangeal (MCP) joint symptoms or dysfunction. We have treated 11 patients who had chronic pain and swelling, but without extensor tendon subluxation, for an average of 7.4 months. Only two responded to nonoperative treatment. The nine who had exploratory surgery had a consistent anatomic lesion that consisted of a partial, arcuate tear of the sagittal fibers. All the patients improved postoperatively. Cadaver dissections of the dorsal MCP tendon mechanism in 11 fresh specimens (44 MCP joints) demonstrated that neither partial nor complete transection of the ulnar sagittal fibers produces radial dislocation of extensor tendons. Radial sagittal fiber transections frequently produced ulnar tendon dislocation. Patients who have closed impact injuries of the MCP joints and present with longstanding pain, swelling, and limited mobility without extensor tendon migration may have sustained unrecognized partial ulnar sagittal fiber disruption. Repair of the partial sagittal fiber tear and exploration of the MCP joint is indicated.