Observation of the Improvement in the Active Range of Motion by a Short-Term Active Thumb Flexion Exercise Is Helpful in the Diagnosis of Flexion Disturbance in Bilateral Thumbs Due to Anomalous Tendon Slip of Flexor Pollicis Longus - Congenital Flexion Disturbance in Bilateral Thumbs: a Case Report

Abstract

We report an 11-year-old boy with limitation of flexion in both thumbs due to anomalous tendon slips of the flexor pollicis longus (FPL). The patient had been unaware of inability to flex his thumbs until his teacher noticed difficulty in writing. Since there were no flexion creases at the interphalangeal joint on either of his thumbs, severe congenital anomalies such as the absence of thumb flexion force and other disorders were suspected. However, because his active range of motion was improved with a short-term self-active flexion exercise program, he was diagnosed as having congenital anomalous tendons with FPL insertion sites other than the tendons of his other fingers. Surgical division of the anomalous tendon slips alone yielded a good functional outcome.