Entrapment of the extensor pollicis longus tendon in a pediatric Smith fracture

Abstract Rationale: Most pediatric distal radius fractures are effectively treated nonoperatively; however, operative intervention is indicated in patients with open and highly unstable fractures, in those with concomitant neurovascular injuries and in patients whom soft tissue interposition between fracture fragments precludes anatomical reduction. Notably, soft tissue interposition between fracture fragments is diagnostically challenging. Surgeons must be mindful of this rare complication for early detection and prompt treatment. Patient concerns: A 14-year-old boy presented to the emergency department with left wrist pain after falling from a bicycle. Plain radiography and computed tomography revealed a displaced Smith fracture, which was irreducible by closed reduction, necessitating open reduction and volar plate fixation. The patient reported inability to extend his thumb at his 6-week postoperative follow-up visit. Diagnosis: Ultrasonography showed extensor pollicis longus (EPL) tendon entrapment near the fracture site. Interventions: A second operation was performed 10 weeks after the first surgery, and intraoperative exploration revealed EPL tendon entrapment. The EPL tendon was torn to shreds; therefore, extensor indicis proprius tendon transfer was performed for EPL tendon reconstruction. Outcomes: The patient's thumb motion was completely restored after the second operation. Lessens: EPL tendon entrapment in a pediatric Smith fracture is rare. Signs of EPL tendon entrapment include inability to perform active thumb extension, dorsal wrist pain radiating along the course of the EPL tendon, which is exacerbated by thumb flexion, a tenodesis effect elicited on thumb examination, and difficulty in anatomical fracture reduction. Surgical exploration of the EPL tendon is warranted in patients presenting with any of these signs following attempted reduction of a Smith fracture.