Absence of the Pronator Quadratus Muscle Precluding Distal Nerve Transfer

The branch of the anterior interosseous nerve to the pronator quadratus (PQ) is increasingly used as a donor nerve for end-to-end and reverse end-to-side nerve transfers. The anatomy of the PQ (and its nerve branch) is generally considered reliable in the absence of prior trauma. In this report, we describe a patient with an absent PQ despite intact clinical examination of other muscles supplied by the anterior interosseous nerve. The absence of the PQ precluded the use of its nerve as a donor nerve for transfer.