Abductor Pollicis Longus and Extensor Pollicis Brevis Nerve Transfer to Ulnar Motor for High Ulnar Nerve Injury When Anterior Interosseous Nerve Is Not Available Michael J.
Franco, MD, Plastic surgery, Washington University, St. Louis, MO, John R. Barbour, MD,
Plastic surgery, Georgetown University, Washington, DC and Thomas H. Tung, MD Division of Plastic and Reconstructive Surgery, Washington University School of Medicine, St. Louis, MO
Introduction: Reconstruction of combined proximal median and ulnar nerve injuries has been described with transfers from the posterior interosseous nerve (PIN) using long nerve grafts. Shortening the distance for regeneration may provide faster recovery and superior long-term outcomes for these devastating injuries. We present an alternate technique for reinnervation of ulnar intrinsic function using the more distal branches to abductor pollicis longus (APL) and extensor pollicis brevis (EPB) to provide a shorter distance for re-innervation. Materials and Methods: Eleven cadaver upper extremities were dissected, measuring the APL and EPB branches of the PIN and their distance from the lateral epicondyle (LE) and the ulnar nerve near the wrist. We additionally present two cases of combined high median and ulnar nerve injury reconstructed utilizing nerve transfers from the bifurcation of the APL/EPB branches to the motor fibers of the ulnar nerve using a nerve graft. Results: Cadaveric dissection data measured the branching pattern of the APL/EPB branches of the PIN and the length of nerve graft required to transfer to the ulnar nerve approximately 9 cm from the wrist crease. A common branch point of the APL/EPB was found in all of our specimens and the mean distance from this bifurcation to the LE was 12.9 cm (± 1.8). The mean distance from the APL/EPB bifurcation to the ulnar nerve at the pisiform was 16.5 cm (±1.7) when the shortest route was taken around the ulnar side of the wrist. When traversing the interosseous membrane, the mean distance was 15.4 cm (± 1.8). Assuming the pisiform approximates the wrist crease, to reach a point 9 cm proximal to the wrist crease, a graft of approximately 7 cm would be needed for the transfer. Clinical outcome data remains limited by time from transfer. Sural nerve or medial antebrachial cutaneous nerve grafting was used for reconstruction of the deficits. At longest available follow-up, the first patient has early recovery of intrinsic musculature with place-and-hold function (11 months). Conclusions: Cadaveric measurements estimate that a nerve graft of 7 cm will be required for the transfer of the APL/EPB nerve branches to ulnar motor. This transfer has the potential to require less nerve regeneration than previously described PIN branch transfers. Early clinical outcomes are limited but remain encouraging. In selected patients, this represents a safe and reasonable option for intrinsic re-innervation in the face of combined ulnar and median nerve injury.
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