A 24-year-old falls on an outstretched thumb while skiing. There is tenderness over the ulnar side of the thumb metacarpophalangeal joint with laxity to valgus stress. Stress radiographs show the avulsed ulnar collateral ligament displaced proximally and lying superficial to the adductor aponeurosis. Why does this finding mandate surgery rather than splinting?

• A Splinting causes irreversible stiffness of the metacarpophalangeal joint
• B The interposed adductor aponeurosis prevents ligament healing back to its insertion ✓
• C The ulnar collateral ligament has no synovial covering and cannot heal
• D Conservative treatment always leads to chronic radial collateral instability

Explanation

This is a Stener lesion complicating gamekeeper thumb. When the ulnar collateral ligament avulses distally, the distal end can be caught proximal to the leading edge of the adductor aponeurosis, so the ligament lies outside the aponeurosis and cannot reunite with its insertion on the proximal phalanx base. Untreated, this produces chronic pinch weakness and instability, hence primary surgical repair is indicated.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.