The Anatomy of Nerve Transfers Used in Tetraplegic Hand Reconstruction

To evaluate the anatomy of nerve transfers used to reconstruct wrist extension, hand opening, and hand closing in tetraplegic patients. Nerve transfers were completed on 18 paired cadaveric upper limbs. The overlap of donor and recipient nerves was measured, as well as the distance to the target muscle. Axons were counted in each nerve and branch, with the axon percentage calculated by dividing the donor nerve count by that of the recipient. Transfers with overlap of the donor and recipient nerve were from the radial nerve branch to extensor carpi radialis brevis to anterior interosseous nerve (AIN) and from the branch(es) to supinator to posterior interosseous nerve. The extensor carpi radialis brevis to AIN had the shortest distance to the target, with the branch to brachialis to AIN being the longest. The nerve transfers for wrist extension had the highest axon percentage. Of the transfers for hand closing, the brachialis to AIN had the highest axon percentage, and the branch to brachioradialis to AIN had the lowest. The anatomical features of nerve transfers used in tetraplegic hand reconstruction are variable. Differences may help explain clinical outcomes. This study demonstrates which nerve transfers may be anatomically favorable for restoring hand function in tetraplegic patients.