Significance of elbow extension in reconstruction of prehension with reinnervated free-muscle transfer following complete brachial plexus avulsion.

Thirty-one patients with complete avulsion of the brachial plexus underwent reconstruction of elbow extension by intercostal nerve transfer following reconstruction of prehension with either a single or double free-muscle transfer. Long-term results of elbow extension were evaluated in 24 patients. Reinnervation of the triceps muscle took longer than that of the transferred muscle on serial electromyographic examinations, and the eventual strength of the triceps muscle was weak. None attained M5 grade, 2 achieved M4 grade, 4 achieved M3 grade, 8 achieved M2 grade, 5 achieved M1 grade, and another 5 achieved M0 grade. However, despite the weak recovery, 14 patients were able to obtain useful functional recovery of the triceps muscle, enabling it to stabilize the elbow joint against the transferred muscle, which acted as simultaneous elbow flexor and wrist or finger extensor. Elbow stability is imperative in order to obtain voluntary finger function following free-muscle transfer. Should the triceps muscle fail to recover following intercostal nerves neurotization, transferring the reinnervated infraspinatus to the triceps is an optional procedure to provide stabilization of the elbow.