Flexor digitorum profundus common to thumb and index finger, associated with a post-traumatic distal adherence of both tendons.

The existence of connections, in the form of tendon slips, between the tendons of the flexor pollicis longus and the flexor digitorum profundus indicis has been described by different authors as being a relatively frequent anomaly. Complete fusion between the two muscles, however, must be considered a very rare anomaly. A bilateral case is described, in which the right hand also had post-traumatic adhesions between the two tendons.