Outcomes of Rerouting the Palmaris Longus to Extensor Pollicis Longus Tendon Transfer through the Second Extensor Compartment for Radial Nerve Palsy

Background: A palmaris longus (PL) to extensor pollicis longus (EPL) is a standard tendon transfer used to restore thumb extension in patients with radial nerve palsy. This transfer is done by withdrawing the EPL from the third compartment and passing it subcutaneously to reach the PL. We modified this transfer by rerouting the EPL through the second extensor compartment to improve the retropulsion of the thumb. The aim of this study is to report the outcomes of this modified transfer. Methods: Four patients with traumatic radial nerve palsy underwent the modified PL to EPL transfer. They also underwent transfer of the pronator teres (PT) to extensor carpi radialis brevis (ECRB) and flexor carpi radialis (FCR) to extensor digitorum communis (DC). Patients were followed up for at least 1 year after surgery. The data with regard to age, gender, cause of radial nerve palsy, duration between injury and surgery, and duration of follow-up was recorded. At final follow-up, the arc of motion at the interphalangeal joint (IPJ), metacarpophalangeal joint (MCPJ), palmar and radial abduction and retropulsion were measured for the reconstructed thumb and contralateral normal thumb. Results: All patients were male, with a mean age of 34.3 (range, 19-46) years. The mean duration between the injury and surgery was 15.9 (7-27) months, and the mean post-operative follow-up period was 16.8 (12-25) months. All patients recovered good thumb function. The mean arc of motion of the affected and contralateral thumb were IPJ flexion: 52 degrees/80 degrees; IPJ extension: 21 degrees/14 degrees; MCPJ flexion: 30 degrees/33 degrees; MCPJ extension:24 degrees/31 degrees, radial abduction: 70 0 /74 0 ; palmar abduction: 68 degrees/75 degrees and retropulsion: 4.8cm/5.0cm. Conclusion: Rerouting the PL to EPL tendon transfer through the second extensor compartment in radial nerve palsy can restore good thumb function especially retropulsion.