Collateral ligament injuries of the metacarpophalangeal joints of the fingers.

Although complete collateral ligament tear and instability involving the metacarpophalangeal joints of the fingers, especially those on the radial aspect of the index finger, are rare, they may be underdiagnosed, underestimated, and potentially disabling. Awareness and suspicion of the injury, coupled with careful physical and imaging examinations, confirm the diagnosis and its extent. Early operative repair results in favorable outcomes in most cases. Chronic instability may lead to pain, weakness, and arthritis. Late ligament repair or reconstruction is typically slightly less reliable than acute repair, yet often improves outcomes. Arthritic joints may require reconstruction.