Recurrent volar dislocation of the metacarpophalangeal joint of the thumb with radial collateral ligament injury: A case report.

Introduction: A volar dislocation of the metacarpophalangeal (MCP) joint of the thumb is a rare trauma, and in combination with a radial collateral ligament (RCL) injury is much rarer. We present a surgical case with a recurrent volar dislocation of the MCP joint of the thumb with RCL injury.

Presentation Of Case: A 47-year-old man was referred to our hospital in the subacute phase. Open reduction was performed through a dorsal incision and the RCL was repaired. X-rays taken six weeks later revealed a recurrent dislocation of the MCP joint. At the revision surgery, the extensor pollicis brevis (EPB) was detached from the proximal phalanx. As there was volar tightness, the volar plate was incised horizontally and the EPB was attached to the proximal phalanx. The final X-rays six months post-operatively revealed that the MCP joint was slightly subluxated but there was no pain on motion.

Discussion: This case revealed that it is not enough only to repair the RCL to reduce a volar dislocation of the MCP joint of the thumb with an RCL injury. It revealed that re-attachment of the extensor tendons and the volar procedure are also important for a perfect reduction of a recurrent volar dislocation of the MCP joint of the thumb.

Conclusion: For a volar dislocation of the MCP joint of the thumb with RCL injury, it is important not only to repair the RCL, but also to perform arthroplasty with the extensor tendons and a volar procedure to prevent recurrent dislocation after surgery.