OrthoNet

THUMB CMC JOINT DISLOCATION

Anatomy

There are four main ligaments that support this joint - the anterior oblique (volar) ligament (AOL), dorsoradial, ligament, posterior oblique ligament, and the intermetacarpal ligament. It is not agreed upon which is the most important.
Pure dislocations are uncommon - found often in motorcyclists with the handlebars driving the bone out. Because of the strong AOL attachment, most of these are Bennett fracture-subluxations

Treatment
Closed reduction and K-wiring with the thumb hyperpronated (the most stable position of the joint), with up to 8-10 weeks of immobilization. These frequently redisplace.
If chronic, CMC arthroplasty or arthrodesis.