A Case of Palmar Dislocation of the Second to Fourth Carpometacarpal Joints

Owing to their articular structure and strong ligaments, the carpometacarpal joints (CM joint), other than that of the thumb, are rarely dislocated. This type of dislocation has been reported to comprise less than 1% of injuries of the hand. Cases of palmer dislocation are especially rare, and in Japan only seven cases of multiple palmar dislocations have been reported, including the one we studied. We recently treated a 21-year-old male who collided with the side of a large car while driving a motorcycle and gripping its handlebars. As a result of the collision, the handlebar was turned strongly to the right, injuring the patient's right hand. On initial radiographic examination, a diagnosis of palmar dislocation of the second through fourth CM joints of the right hand accompanied by a metacarpal transverse fracture ot the right thumb and a metacarpal oblique fracture of the small finger was made. Surgery was immediately performed under a brachial plexus nerve block of the right arm. The CM joints were easily reduced by manipulation, and no redislocation was observed postoperatively. The metacarpal fractures of the thumb and the small finger were fixed with miniscrews. Shortly after surgery, finger exercise was begun, with good results. We speculated that the patient's injury was due to rotating force around the fifth metacarpal bone.

Hasegawa K, et al