The Use of Ultrasonography to Identify the Intersection of the Dorsomedial Cutaneous Nerve of the Hallux and the Extensor Hallucis Longus Tendon: A Cadaveric Study

Abstract

Terminal branches of the superficial fibular nerve are at risk of iatrogenic damage during foot surgery, including hallux valgus rigidus correction, bunionectomy, cheilectomy, and extensor hallucis longus tendon transfer. One terminal branch, the dorsomedial cutaneous nerve of the hallux, is particularly at risk of injury at its intersection with the extensor hallucis longus tendon. Iatrogenic injuries of the dorsomedial cutaneous nerve of the hallux can result in sensory loss, neuroma formation, and/or debilitating causalgia. Therefore, preoperative identification of the nerve is of great clinical importance. The present study used ultrasonography to identify the intersection between the dorsomedial cutaneous nerve of the hallux and the extensor hallucis longus tendon in cadavers. On ultrasound identification of the intersection, dissection was performed to assess the accuracy of the ultrasound screening. The method successfully pinpointed the nerve in 21 of 28 feet (75%). The sensitivity, positive likelihood ratio, and positive and negative predictive values of ultrasound identification of the junction of the dorsomedial cutaneous nerve and the extensor hallucis longus tendon were 75%, 75%, 100%, and 0%, respectively. We have described an ultrasound protocol that allows for the preoperative identification of the dorsomedial cutaneous nerve of the hallux as it crosses the extensor hallucis longus tendon. The technique could potentially be used to prevent the debilitating iatrogenic injuries known to occur in association with many common foot surgeries.

The potentially dangerous zone of the dorsomedial cutaneous nerve in minimally invasive surgery for hallux valgus: a cadaveric study

“…Furthermore, identifying the sentinel vein in MIS can be challenging [ 29 ]. Other methods, such as ultrasound, have also been reported for identifying the DMCN, but they are not as simple and convenient in MIS [ 30 ]. Based on our study and previous research on the DMCN at the level of the MTPJ, we can effectively protect the DMCN in MIS for HV, thereby preventing post-surgical numbness.…”

A Review of Extensor Hallucis Longus Variants Featuring a Novel Extensor Primi Internodii Hallucis Muscle Merging With Extensor Hallucis Brevis

“…Although most variants exist medial to the normal EHL tendon, in certain cases, such as the EPIH described in the present study, an accessory tendon might exist lateral to the normal EHL tendon (29). It is important to note that ultrasonography could be used to identify both the EHL tendon and the dorsomedial cutaneous nerve of the hallux as it crosses the EHL tendon (43). Therefore, preoperative ultrasonography could aid in identifying EHL variants and the anatomic relationships between EHL variants and the nearby nerves to avert iatrogenic injuries.…”