Snapping Wrist From Bowstringing of the Digital Flexors After Carpal Tunnel Release: A Case Report.

Symptomatic bowstringing of digital flexor tendons is a rare complication of carpal tunnel release (CTR). Two weeks after open CTR, a 47-year-old man with severe carpal tunnel syndrome had relief of his preoperative median paresthesia but complained of new-onset painful snapping of the wrist and transient ulnar paresthesia occurring with wrist dorsiflexion and concomitant digital flexion. Physical examination localized the audible snapping to the hook of hamate (HOH) where manual pressure eliminated the wrist motion-induced snapping and the associated ulnar paresthesia. Wrist radiographs showed stage III scapholunate advanced collapse (SLAC) with marked palmar subluxation of the lunate. Wrist magnetic resonance imaging revealed palmar and ulnar subluxation of the digital flexors over the HOH due to the mass effect of the palmarly displaced lunate and the chronic carpal malalignment. The snapping wrist and accompanying ulnar paresthesia resolved after HOH excision, and no additional treatment for the asymptomatic SLAC wrist deformity was required. Satisfactory clinical outcome was observed at 5-year follow-up.