Traumatic correction of Linburg-Comstock anomaly: a case report

Linburg-Comstock anomaly describes an anatomical variant of flexor tendons of the hand. Flexor pollicis longus (FPL) sends a connecting tendon to flexor digitorum profundus (FDP), causing simultaneous flexion at the distal interphalangeal joint (DIPJ) of the index finger when the interphalangeal joint (IPJ) of the thumb is flexed. Epidemiological studies have revealed a unilateral prevalence as high as 31% of individuals; however, the condition rarely causes symptoms. The anomaly can present with a restrictive flexor tenosynovitis, requiring explorative surgery to confirm the diagnosis and disconnection of the anomalous tendon slip to relieve symptoms. We describe the case of a rock climber who suffered a forced extension injury to the DIPJ of the right index finger, resulting in traumatic rupture of his anomalous FPL-FDP connecting tendon. This is the first reported case of rupture of a Linburg-Comstock anomaly. Through rupture of this anomalous tendon, the patient can be viewed as having corrected his aberrant tendon to conform with the more prevalent anatomical configuration and function. We identified the rupture using dynamic ultrasound of the wrist; to our knowledge, this technique has not been described previously in the literature. We recommend the use of this imaging modality to confirm diagnosis, thus avoiding explorative surgery.