A cricketer jams his right ring finger while fielding. He cannot actively extend the distal interphalangeal joint, though passive extension is full and there is no bony fragment on X-ray. The most likely injured structure is:

• A Extensor tendon at its insertion into the base of the distal phalanx ✓
• B Central slip of the extensor expansion
• C Flexor digitorum profundus insertion
• D Radial collateral ligament of the proximal interphalangeal joint

Explanation

Forced flexion of an extended finger avulses the extensor tendon from the base of the distal phalanx, producing a mallet finger: loss of active DIP extension with a normal passive range. Tendon-only injuries may show no radiographic change. Flexor digitorum profundus avulsion causes loss of active DIP flexion, while central slip rupture produces a boutonniere deformity with PIP extension weakness, not isolated DIP extension loss.

Reference: Apley's System of Orthopaedics and Fractures, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.