Combined hypothenar fat pad flap and delayed neurorrhaphy for transected thenar branch during carpal tunnel release

Abstract

Because of its variable origin and course, the thenar branch of the median nerve is at risk during carpal tunnel release. Transection results in thenar atrophy and non-functioning of the opponens pollicis, abductor pollicis brevis and flexor pollicis brevis muscles. A late neurorrhaphy and hypothenar fat pad flap were performed to restore nerve conduction and thus muscle function after accidental transection of the thenar branch of the median nerve during an open carpal tunnel release 216 days earlier. During the eight months follow-up, we noted progression in daily functioning, muscle strength and a decrease in muscle atrophy. Electromyography confirmed extensive improvement of the thenar motor function. The hypothenar fat pad flap may have an advantage in late nerve repair, providing a tension-free gliding surface, as well as arterial blood supply to the newly repaired nerve branch.