Treatment of Traumatic Thumb Dislocation
In this review article, surgeons from the Netherlands bring us up-to-date on the treatment of traumatic thumb dislocations. Dislocation of the carpometacarpal (CMC) joint (base of the thumb at the wrist) is very rare.

The thick, strong joint capsule protects the joint from dislocation. Instead, the base of the metacarpal (thumb) bone breaks off first -- before the joint can dislocate. This injury is called an avulsion fracture.

The CMC joint is very complex. It has been called the saddle joint. The surface of the bones fit together like a saddle on a horse's back. This configuration gives the thumb a wide range of movements, including thumb opposition. Four strong ligaments around the joint stabilize and hold everything tightly together.

The best treatment for a thumb CMC dislocation is still widely debated. The extent of ligamentous damage may dictate whether or not surgery is needed. Sometimes putting the joint back in place and using a simple cast is all that's needed. This is called a closed reduction with casting.

Closed reduction is possible in an acute injury when the joint remains stable. Instability may require using a wire or pin to hold the joint together. In other cases, reconstruction of the torn ligaments is needed to restore thumb motion and function. Tendon graft or tendon transfer may be used to replace the ruptured ligament.

For a chronically dislocated CMC joint, more extensive surgery may be required. An open incision is made, the joint is lined up and held in place with wires. Torn ligaments are repaired or replaced. A cast is placed on the hand and wrist to immobilize the area.

The authors conclude that the literature (studies done so far) do not support the use of aggressive treatment. Open reduction with ligament reconstruction is not always the first choice of treatment. Each patient must be evaluated for joint stability (or instability) when deciding on the best course of action.
References
B. Bosmans, MD, et al. Traumatic Thumb Carpometacarpal Joint Dislocations. In Journal of Hand Surgery. March 2008. Vol. 33A. No. 3. Pp. 438-441.