Nerve and Free Gracilis Muscle Transfers for Thumb and Finger Extension Reconstruction in Long-standing Tetraplegia

Abstract

With spinal cord injuries, muscles below the level of the lesion remain innervated despite the absence of volitional control. This persistent innervation protects against denervation atrophy and may allow for nerve transfers to treat long-standing lesions within the spinal cord. We tested the hypothesis that in chronic spinal cord lesions, muscles remained viable for reinnervation. To test this hypothesis, we operated on 7 patients with tetraplegia to reconstruct thumb and finger extension after a mean interval of 5 years since injury. During surgery, if electrical stimulation of the posterior interosseous nerve (PIN) produced muscle contraction, the nerve to the supinator (NS) was transferred to the PIN. If no contractions were demonstrated, the muscles of the extensor compartment of the forearm were replaced via a free gracilis transfer with innervation supplied by the NS. After an average of 26 months, M3 recovery of thumb and finger extension was observed in the 3 upper limbs from the 2 youngest patients who underwent a nerve transfer. None of the free gracilis-treated patients achieved scores above M2. In our youngest patients aged 27 and 34 years, who were operated on 6 years after spinal cord injury, transfer of the NS to the PIN partially restored hand span. Therapeutic V.