Functional deficit after transfer of the pronator teres for acquired radial nerve palsy.

PURPOSE: A suitable muscle motor in reconstruction after acquired never injury should have adequate strength to perform the desired task, be aligned in the direction of pull, have synergistic action, and not result in unacceptable functional loss. In radial nerve palsy, the pronator teres is the most common motor donor used to restore wrist extension. Although the pronator teres remains aligned to provide pronation, the force deficit of the transfer is not known.

METHODS

We used 6 cadavers and 6 patients to determine the loss of pronation strength both experimentally and clinically.

RESULTS

Cadaveric testing showed a loss of pronation produced with similar load after transfer of the pronator. Clinical testing showed statistically significant loss of pronation ranging from 24% to 44%, depending on the method of testing. This deficit may be an important consideration in some clinical situations when transfers are used while waiting for radial nerve function to return.

CONCLUSIONS

In the cadaveric biomechanic testing, we simulated the pronator teres-to-extensor carpi radialis brevis tendon transfer and showed a decreased range of motion and force developed after transfer. The clinical arm of the study confirmed our biomechanic findings by showing the loss of pronation function. This loss may be an important factor when planning reconstruction for radial nerve injuries.

TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.