Boutonniere deformity

Flexion deformity of PIP joint. Caused by interruption of the central slip of the extensor tendon. The lateral slips separate and the head of the proximal phalanx pops through the gap like a finger through a buttonhole.

Seen after trauma or in rheumatoid disease. Post-traumatic rupture can sometimes be repaired; the chronic deformity of RA usually defies correction.

Neuromuscular disorders of the hand

Ulnar claw-hand

Hyperextension MCP + flexion PIP. Paralysis of intrinsic muscles. A.k.a. intrinsic minus.

Shortening of intrinsic muscles

A.k.a. intrinsic plus. Flexion MCP + extension IP + adduction of thumb. Main causes = spasticity, scarring. Rx: Release the intrinsic muscles where they cross the MCP joints.

Ischaemic contracture of forearm muscles

Follows circulatory insufficiency due to injuries at or below the elbow. Shortening of long flexors. Fingers held in flexion, can be straightened only when wrist is flexed. Rx: Release shortened muscles at their origin above the elbow or excise dead muscles and restore finger function with tendon transfers.

Apley's 175