Brachioradialis tendon transfer for a thumb and finger extension disorder owing to distal-type cervical spondylotic amyotrophy: a case report

To reconstruct finger extension in distal-type cervical spondylotic amyotrophy, wrist flexor tendons are commonly selected as the donor tendons. However, distal-type cervical spondylotic amyotrophy predominantly affects the C8 myotome, and therefore the wrist flexor muscles may also be impaired. The brachioradialis is mainly innervated by the C6 and is therefore less likely to be affected, it represents a favorable option as a donor tendon. However, there are few reports describing the use of the brachioradialis as a donor tendon. A 72-year-old man presented with limited active extension of his left ring and small fingers and thumb. Posterior cervical decompression was performed for cervical spondylotic amyotrophy (C8 segment involvement); however, at 12 months postoperatively, thumb and finger extension remained impaired. Instead of a wrist flexor transfer, we performed a brachioradialis tendon transfer to the extensor pollicis longus and extensor digitorum communis tendons. At 2 - year postoperative final follow-up, the extension lags of the 4^th and 5^th metacarpophalangeal joints and thumb had improved. His Disabilities of the Arm, Shoulder, and Hand score improved from 30 to 11.6 postoperatively. In finger and thumb extensor paralysis owing to distal cervical spondylotic amyotrophy, the brachioradialis muscle is typically spared and can be considered a donor for tendon transfer. This procedure, combined with extensive release of the fascial attachments, effectively improved dysfunction of finger and thumb extension without resulting in significant functional loss.