What hand deformity is characterized by MCP hyper-extension and PIP flexion?

The hand deformity characterized by metacarpophalangeal (MCP) hyper-extension and proximal interphalangeal (PIP) flexion is known as claw fingers. This condition often occurs due to nerve damage, particularly to the ulnar nerve, resulting in an imbalance between the muscles that flex and extend the fingers.

In claw fingers, the excessive extension at the MCP joint is typically caused by weakness in the intrinsic muscles of the hand, which are responsible for flexing these joints. As a result, the lumbrical and interosseous muscles cannot properly balance the action of the extrinsic flexor muscles, leading to the distinctive posture where the fingers curl into a claw-like position. This deformity can affect one or more of the fingers and can cause functional difficulties as well as aesthetic concerns.

Ape hand, bishop's hand, and trigger finger present with different characteristics and involve various combinations of muscle imbalances and dysfunctions, making them distinct from claw fingers. Understanding these nuances is essential for recognizing and diagnosing hand deformities effectively.