Mapping the intersection point of the dorsomedial cutaneous nerve of the hallux and the extensor hallucis longus tendon to prevent iatrogenic injury during foot operative procedures
Authors: Miller Kyle D , Swearingen Jordan V , Burns Daniel T , Zdilla Matthew J. , Lambert H. Wayne 
Published: November 2023

Introduction

The dorsomedial cutaneous nerve (DMCN) of the hallux is a terminal branch of the superficial fibular (peroneal) nerve which supplies the skin of the medial aspect of the great toe. This cutaneous nerve branch is particularly vulnerable to iatrogenic injury during operative procedures involving the joints of the hallux, including hallux valgus correction, hallux ridigus correction, bunionectomy, and cheilectomy. Moreover, the DMCN of the hallux can be damaged during extensor hallucis longus (EHL) tendon transfer procedures due to the fact this nerve travels superficial to EHL tendon while traveling obliquely in the dorsum of the foot from a proximal lateral location to a distal medial position.

Methods

This prospective study involved cadaveric dissection of 20 legs to identify the location of where the dorsomedial cutaneous nerve (DMCN) of the hallux intersects the medial border of the extensor hallucis longus (EHL) tendon. Upon identification, further dissection was performed to follow the entire course of the superficial fibular nerve and the EHL tendon as well as their branching patterns. After marking the intersection point with a fine needle probe, digital photographs of the medial and dorsal aspects of each foot were taken of each foot. A ruler with length demarcations, specific to the millimeter, was held flush with the foot during photography. Digital photographs were then analyzed using the ruler markings as reference for measurement calibrations.

Results

The intersection of where the DMCN of the hallux superficially crosses the medial border of the extensor hallucis longus (EHL) tendon was measured from a variety ways, including the angle of its intersection (154.7 ± 11.1 degrees) and its position relative to the distal‐most dorsal surface of the hallux (14.1 ± 1.2 cm). Additional measurements derived from this prospective study will be presented.

Conclusions

This prospective study identified the location at which dorsomedial cutaneous nerve (DMCN) of the hallux intersects the medial border of the extensor hallucis longus (EHL) tendon and mapped this intersection point in relation the other landmarks of the foot. The goal of this study is to derive confidence intervals for surgeons to identify the location of this cutaneous nerve to help prevent its iatrogenic damage during surgeries on the joints of the big toe or during extensor hallucis longus tendon transfer surgeries. If these measurements are used in conjunction with current techniques, such as ultrasound or the fourth toe flexion maneuver, the rate of successful mapping of the DMCN of the hallux may be further enhanced. Currently, additional dissections are being performed to increase the N‐value of the study.

Support or Funding Information

The research of Kyle D. Miller and Jordan V. Swearingen was supported by the West Virginia University Initiation to Research Opportunities (INTRO) Program.