Extensor Pollicis Longus Tendon Translocation with a History of Thumb Polydactyly Surgery.

Nontraumatic and nonrheumatoid translocation of the extensor pollicis longus (EPL) tendon at the metacarpophalangeal (MP) joint is rare and may result from insufficiency of the dorsoradial capsule and sagittal band complex. We report a 41-year-old carpet weaver woman with a history of childhood thumb polydactyly reconstruction who presented with painful EPL translocation during thumb motion. She had previously undergone unsuccessful surgery for presumed EPL snapping at the wrist. Intraoperative findings revealed a normal extensor pollicis brevis tendon and 2 EPL tendons, both displaced ulnarly at the MP joint, along with a deficiency of the radial sagittal band. Surgical management consisted of ulnar sagittal band release and reconstruction of the dorsoradial stabilizing structures by reefing the residual radial EPL aponeurosis to the MP joint capsule to centralize the tendon. At 6-month follow-up, the patient had complete resolution of symptoms and stable tendon tracking. This case highlights the potential for late EPL instability following thumb polydactyly reconstruction, likely because of loss of radial restraint, unopposed ulnar vector, and repetitive stress.