The Super Supinator! Reliably Restoring Active Hand Opening in C5/6 Tetraplegia Using the Supinator Nerve to Posterior Interosseous Nerve Transfer

Abstract

Objective/Hypothesis: Achieving satisfactory hand opening as a part of surgical reanimation for the upper limb post cervical spinal cord injury (SCI) has been an elusive goal. This study presents outcomes in 11 consecutive patients (17 limbs) who underwent supinator nerve to posterior interosseous nerve (PIN) transfers for the restoration of finger and thumb extension. Materials and Methods: Eleven patients (17 limbs) with a mean age of 25.6 years and a C5 to C7 motor complete SCI underwent supinator nerve to PIN transfers between 5 and 52 months post injury at a single center. Prior to surgery, all patients had preserved biceps and supinator function, but absent digital extension. All patients received follow-up hand therapy and underwent a final evaluation at a mean age of 19.3 months (range, 14-26) post surgery. Clinical outcome measures included manual muscle testing and measurement of first web space opening. Canadian Occupation Performance Measure (COPM) and patient satisfaction scores were recorded. Results: All 17 transfers resulted in active, voluntary finger and thumb extension. The mean Medical Research Council Grade for power in extensor digitorum communis was 3.9 and for extensor pollicis longus was 3.7. The mean first web space opening was 99.7 mm. As a consequence, patients were able to open their hand to place it around or release an object and to extend their hand in greeting. Further benefits included counteracting spasticity in the finger flexors and reducing the radial deviation of the wrist through the reanimation of extensor carpi ulnaris. At final review, all patients had functional supination even with the elbow extended. Conclusions: The supinator to PIN transfer provides a promising option for restoring finger extension in people with C5/6/7 cervical SCI and has high rates of technical success along with high patient satisfaction rate. It can be performed in combination with other tendon or nerve transfers to maximize functional reconstruction of the upper limb in tetraplegia.