Failure of flexor pollicis longus repair caused by anomalous flexor pollicis longus to index flexor digitorum profundus interconnections: a case report.

We describe a case of an early rupture of a repaired flexor pollicis longus tendon in a young woman. The cause of failure was an anomalous tendinous band that connected the tendon of the flexor pollicis longus to the tendon of the flexor digitorum profundus of the index finger. Forceful flexion of the unrestricted index finger applied a tensile force that was transmitted through the anomalous band to the repaired site and resulted in repair failure.