Elbow flexion strength and contractile activity after partial ulnar nerve or intercostal nerve transfers for brachial plexus injuries

We compared the outcomes of 23 partial ulnar nerve and 15 intercostal nerve transfers for elbow flexion reconstruction in patients with C56 or C567 brachial plexus injuries using manual muscle power, dynamometric measurements of elbow flexion strength and electromyography. The range of elbow flexion and muscle strength recovery to Grade 3 or 4 were comparable between the two groups. The patients with C567 injuries had significantly stronger eccentric contraction after the partial ulnar nerve transfer than after the intercostal nerve transfer (p < 0.05). Electromyography of individual muscles demonstrated that the patients with partial ulnar nerve transfers were unable to voluntarily isolate biceps contraction and recruited forearm flexors and extensors. The patients after partial ulnar nerve transfer had significantly more activity of the forearm muscles during concentric elbow flexion than after intercostal nerve transfers (p < 0.05). We conclude that partial ulnar nerve transfers were superior to intercostal nerve transfers when assessed quantitatively with the dynamometer to evaluate elbow flexion, although simultaneous recruitment of forearm muscles may have contributed to the increased elbow flexion strength in the patients with the partial ulnar nerve transfer.

Level of evidence: III