Vascularized Anterior Interosseous Nerve Transfer: A Novel Concept to Treat Ulnar Nerve Injury

Ulnar nerve injuries, particularly above the elbow level, are complex, with limited treatment options that often result in compromised functional outcomes. Despite variable outcome data, the anterior interosseous nerve (AIN) to ulnar motor nerve transfer is a well-known and frequently used treatment option aimed at enhancing nerve recovery and providing superior outcomes compared with nerve grafting and conventional nerve repair while carrying low morbidity.¹ AIN nerve transfer can be performed as either an end-to-end or supercharged end-to-side (SETS) transfer.² Concurrently, when considering nerve reconstruction using autologous nerve grafts, vascularized nerve grafts (VNGs), which integrate an inherent vascular supply/pedicle, have been shown to provide superior outcomes compared with non-VNGs.³ Although both the AIN to ulnar motor nerve transfer and the concept of VNGs are well known, the combination of these 2 approaches has not been reported in the context of ulnar nerve reconstruction, to our knowledge. In this article, we propose the use of a vascularized AIN (vAIN) nerve transfer with the pronator quadratus (PQ) vascular pedicle and its potential application as a VNG for other nerve reconstructions.

The PQ has been described as a free flap, most commonly as a free functional muscle transfer, with the anterior interosseous vessels representing a consistent, reliable major vascular pedicle to the PQ.⁴ We aimed to use this vascular pedicle to improve the traditional AIN to ulnar motor nerve SETS transfer, with the goal of improving nerve regeneration and the quality of axonal transfer. The AIN transfer is performed along with its corresponding vascularized pedicle. The key step of the nerve transfer is careful dissection of the AIN while preserving the neighboring vascular bundle. The vascular pedicle is identified alongside the AIN, with both the nerve and vascular pedicle being dissected to the mid-portion of the PQ where the AIN begins branching. The pedicle is clipped at the same level as the AIN, and the entire anterior interosseous neurovascular bundle is subsequently dissected proximally. The nerve transfer is then performed as either an end-to-end or SETS transfer to the motor fascicles of the ulnar nerve at the level of the distal forearm. During and following the completion of the nerve transfer, preservation of the vascular supply is confirmed clinically by visible pulsation and nerve bleeding (Fig. 1). (See Video [online], which demonstrates preserved vascular supply to the AIN via the divided vascular pedicle to the PQ.)

Fig. 1.

A photograph of the transected vAIN before nerve transfer.

Video 1. This video demonstrates preserved vascular supply to anterior interosseous nerve via divided vascular pedicle to pronator quadratus.

Download video file ^{(14.2MB, mp4)}

The vAIN to ulnar motor nerve transfer is proposed as a technically feasible, low-morbidity modification of a well-established nerve transfer for the treatment of ulnar nerve injuries. Given the reliable vascular supply and anatomical consistency, the vAIN may also be used as a free VNG, representing a reconstructive option for remote nerve injuries. Although the theoretical basis for this approach is supported by the principles of vascularized nerve grafting, its potential impact on nerve regeneration and functional outcomes has yet to be determined. Further studies are warranted to evaluate clinical outcomes and define its role relative to conventional nonvascularized techniques.

DISCLOSURE

The authors have no financial interest to declare in relation to the content of this article.