Outcomes of Opponensplasty with Transfer of the Palmaris Longus Tendon to the Rerouted Extensor Pollicis Brevis Tendon for Severe Carpal Tunnel Syndrome

<b>Background:</b> Camitz opponensplasty is a widely used reconstruction procedure for severe carpal tunnel syndrome. However, it has several drawbacks, including poor pronation during thumb opposition and a tendency for flexion at the thumb metacarpophalangeal (MP) joint. We developed a novel procedure to overcome these issues while preserving its advantages. <b>Methods:</b> Our procedure involves mini open carpal tunnel release (KnifeLight) and the transfer of the palmaris longus (PL) tendon to the rerouted extensor pollicis brevis (EPB) tendon using the distal part of the PL tendon as a pulley. We assessed sensory and motor function recovery up to 12 weeks postoperatively, and changes in subjective symptoms, satisfaction with surgery and presence of pulley loosening after 1 year. <b>Results:</b> In 47 hands, palmar abduction of the thumb improved from an average of 32° preoperatively to 45° at 4 weeks postoperatively, and tip pinching between the thumb and index finger recovered in all patients by 8 weeks postoperatively. Furthermore, within 4-8 weeks postoperatively, all patients showed improvement in pinching and grasping, enhancing hand function in activities of daily living (ADL). Self-evaluation of surgery in patients followed for more than 1 year was generally favorable. None of the patients who were directly evaluated showed any deviation of the EPB tendon at the pulley. <b>Conclusions:</b> Our technique is a potential alternative to the Camitz procedure as it retains the advantages of the Camitz procedure while overcoming its drawbacks. <b>Level of Evidence:</b> Level IV (Therapeutic).