Chronic sprains of the carpometacarpal joints.

The relatively rigid second and third carpometacarpal joints provide stability for the cantilevered metacarpals of the index and middle fingers, about which the thumb and ulnar metacarpals move, providing spatial adaptation for grasping objects. Although seldom recognized, sprains of the carpometacarpal joints as part of a range of injury which includes subluxations, dislocations, and fractures are apparently common. The entity known as carpe bossu also may be related. The second and third carpometacarpal joints are more susceptible to injury in palmar flexion than in dorsiflexion. The sprain may be acute or chronic. Severe swelling over the carpometacarpal area, with tenderness and weakness without significant roentgenographic findings, is suggestive of the acute sprain, which generally responds to immobilization. The chronic sprain is often overlooked or misdiagnosed. Point tenderness of one or more carpometacarpal joints, a palpable laxity, and crepitus with manipulation are seen as physical findings, in decreasing order of frequency. Lidocaine, 0.5 ml, injected directly into the joint offers dramatic relief. If conservative measures are insufficient, arthrodesis of the joint is relatively simple, symptomatically reliable, and functionally uncompromising, especially of the second and third rays.