A 30-year-old skier falls with his thumb forcibly abducted. He has marked instability of the metacarpophalangeal joint of the thumb on valgus stress testing. A firm, tender lump is palpable on the ulnar side of the joint that becomes more prominent with thumb flexion. The most likely diagnosis is:

• A Rupture of the first dorsal interosseous muscle
• B Stener lesion with interposition of the adductor aponeurosis ✓
• C Dislocation of the trapeziometacarpal joint
• D Avulsion of the abductor pollicis longus tendon

Explanation

Gamekeeper's or skier's thumb is rupture of the ulnar collateral ligament of the thumb metacarpophalangeal joint. When the torn ligament retracts and comes to lie superficial to the adductor aponeurosis, it forms a palpable lump and cannot heal back to bone; this is the Stener lesion. The displaced end becomes more prominent with flexion as the aponeurosis glides over it. Because the ligament is blocked from the bone by the aponeurosis, operative repair is required rather than simple casting.

Reference: Green's Operative Hand Surgery, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.