A 55 yo M presents to the ED w/ thumb pain following an MVC. He states his car spun out of control and he felt the steering wheel slam into the webspace between his thumb and 2nd digit. Pain and swelling have worsened since the time of the accident. An xray is done and shown below. What's the diagnosis? (scroll down for answer)

Answer: Carpometacarpal dislocation of first digit

Carpometacarpal Dislocations

• Cause
• axial load onto digit
• dorsal force in webspace
• RARE
• ususally secondary to high speed mechanism
• Presentation
• swelling, usually dislocated dorsally
• inability to to flex at that joint, inability to make fist
• commonly associated with fracture, nerve injury
• Management
• traction and flexion of joint in attempt to reduce with longitudinal pressure on carpal base
• often unstable and requires surgical intervention
• Follow up
• after successful or unsuccessful reduction, dorsal and volar splint with wrist in 30 degrees extension
• urgent ortho f/u

Ashkenaze DM, Ruby LK. Metacarpal fractures and dislocations. Orthop Clin North Am 1992; 23:19.

German C. Hand and wrist emergencies. In: Bond M, ed. Orthopedic Emergencies: Expert Management for the Emergency Physician. Cambridge: Cambridge University Press; October 31, 2013.