Simultaneous Dislocation of the Carpometacarpal and Metacarpophalangeal Joints of the Thumb in a Motorcyclist

Abstract

Combined dislocation of more than one joint in a single finger is a rare injury. An amateur motorcyclist sustained simultaneous closed dislocation of the carpometacarpal and metacarpophalangeal joints of the thumb as an isolated injury after falling from his motorcycle during an abrupt stop from high speed. The dislocated joints were reduced by closed means on the day of injury. After 18 months, the functional result of his right thumb was excellent. The mechanism of injury and management of this uncommon motorcycle injury is reported.

Floating thumb metacarpal in a motorcyclist: A case report

“…Simultaneous double thumb dislocation seems to be a very rare injury [1][2][3][4][5][6]; it was first described by Moore in 1978 and later named ''floating thumb metacarpal'' by Drosos et al [2].…”

“…Motorcycle riders always grip the handlebar with their fingers above and the thumb below. In a collision, the motorcycle's abrupt stop compresses the soft tissues against the ulnar side of the base of the thumb metacarpal, causing dorsal or dorsoradial CMC joint dislocation [3]. Then, the weight of the motorcycle is transmitted through the handlebar on the palmar surface of the proximal phalanx of the thumb, causing a hyperextension force that leads to MCP dislocation (Fig.…”

“…In this case, open reduction is required through a volar or dorsal approach [10,11]. Pure CMC dislocations are rare [3,11] and may go unnoticed especially in multitrauma patients [2,12]. Their treatment is very controversial.…”

“…In stable closed reductions, some suggest conservative treatment with cast immobilization to maintain the reduction, but there is a risk of long-term instability [1,[3][4][5][6][7][8][9][10][11]. Other authors prefer Kirschner-wire stabilization independent of the reduction method [2,3,12,13]. It is a quick, simple and reproducible procedure [14]; however, articular non-congruence may persist, which can generate osteoarthritis.…”

Complete dislocation of the thumb metacarpal with extreme displacement

“…In a review of earlier English published reports, we found eight cases [1][2][3][4][5][6][7][8], and this injury pattern was described with terms such as simultaneous dislocation, double dislocation, complete dislocation of the metacarpal, and floating thumb metacarpal. In previously reported cases, although the proximal and distal joints were dislocated, the metacarpal was located in its original position.…”