What hand deformity is a result of weak capsular ligaments at the MCP joint?

The hand deformity that results from weak capsular ligaments at the MCP (metacarpophalangeal) joint is known as ulnar drift. This condition is characterized by the deviation of the fingers toward the ulnar side (the side of the little finger) of the hand. When the ligaments that support the MCP joint are weakened, it can lead to instability and subsequent misalignment of the finger joints.

In ulnar drift, the collateral ligaments may stretch over time, allowing the proximal phalanx to shift towards the ulnar side, especially under the influence of muscle pull from the long tendons of the fingers. This often occurs in the context of certain inflammatory conditions, such as rheumatoid arthritis, where joint integrity is compromised due to inflammation and degradation of joint structures.

Understanding this deformity is essential for therapeutic interventions, as addressing the underlying joint instability may help prevent further progression of the deformity and improve hand function.