Dislocations and fracture dislocations of the metacarpophalangeal joint of the thumb.

Due to its exposed position, the MCP joint of the thumb is particularly vulnerable to dislocations and fracture dislocations. Depending on the direction of the injuring force, injuries to the ulnar, radial, and volar aspect of the joint can occur. If high-grade lesions are not identified and treated appropriately during their acute phase, marked instability with associated long-term disability due to weakness and pain in pinch and grip can result. In the absence of a reliable method for diagnosing the Stener lesion, surgical repair of acute, third-degree lesions on the ulnar side of the joint remains the treatment of choice. In the presence of chronic instability, a variety of effective soft tissue reconstructive measures are available. The fact that both acute and chronic injuries enjoy a favorable prognosis with operative repair is due to the fact that operative intervention reliably restores stability to the joint. Mild to moderate loss of motion at the joint is well tolerated functionally. For this reason, arthrodesis remains an exceptionally satisfactory salvage for failed soft tissue reconstructions.