An Anatomical Study of Nerves at Risk During Minimally Invasive Hallux Valgus Surgery

Summary

Minimally invasive surgical (MIS) procedures rely on anatomical references to localize structures not directly visible to the surgeon. This manuscript describes a combined method of plane-by-plane dissection and sectional anatomy of fresh-frozen specimens to locate the structures at risk during MIS procedures.

Abstract

The growing popularity of minimally invasive surgical (MIS) procedures makes it necessary that new anatomical references arise, to aid in tridimensional orientation and localization of structures that are not directly visible to the surgeon. This is especially critical for structures at risk like nerves or blood vessels. Optimization of the handling of cadaveric material and the combination of multiple techniques compensate for the limited availability of adequate specimens. The described protocol combines anatomical plane-by-plane dissection and sectional anatomy of fresh-frozen specimens to help localize relevant structures, such as nerves, arteries, veins and to correctly position the portals during MIS procedures. Depiction of these structures in anatomy textbooks can differ from what is encountered in the surgical field; and for this reason, new anatomical studies with a surgical orientation are needed. However, this is a complex, time-consuming technique requiring specific training. The anatomical references described with the so-called 'clock method' provide the surgeon with an easy and reproducible system to locate the path of the nerves at risk in Hallux Valgus MIS procedures. This model can be extrapolated to many other minimally invasive surgical procedures.

Introduction

Hallux valgus is a common pathology affecting the first toe, in which the proximal phalanx is deviated laterally while the first metatarsal is deviated medially¹. Percutaneous or minimally-invasive surgical (MIS) techniques for hallux valgus were amongst the first described in this discipline, and numerous studies report their benefits but also their risks². Hallux Valgus MIS correction involves osteotomies performed through small incisions using specific surgical instruments. Given that open dissections are not performed, the risk of damage to neurovascular structures is higher than when these are identified during open....

Protocol

This study was approved by the institutional Ethical Committee (Comissió de Bioètica, UB). The dissection procedures were carried out by an experienced anatomist, specifically trained in plane-by-plane dissection technique. This is an essential prerequisite to ensure a successful outcome of the experiment.

1. Preparation

1. Select the specimens to be included in the study. Use below-the-knee cadaveric fresh-frozen human feet.
   1. Exclude the following: any kind of deformities in the leg, ankle or foot (as this could affect the course of the nerves and ultimately affect the results of the study), ulcers, scars or e....

Results

Using the clock method, the dorsomedial and dorsolateral nerves were consistently found between 10 and 2 o'clock (Figure 1). The dorsomedial nerve was found at an average of 26.2° medial to the medial border of the EHL, which corresponds to a zone between 12 and 2 o'clock in a right foot, and between 10 and 12 o'clock in a left foot. The dorsolateral nerve was 32.3° lateral to the medial border of the EHL in average, which corresponds to a zone between 12 and.......

Discussion

The basis of the method used in this study is a combination of sectional anatomy and anatomical plane-by-plane dissection, as it has been practiced historically⁷. This requires not only anatomical knowledge but also specific training for what is a time-demanding technique that greatly relies on the skills of the dissector. Consequently, some anatomical images provided in anatomical textbooks or scientific papers, especially in the field of orthopedic surgery, lack accuracy and are not instructive .......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Adson Non-Toothed dissection forceps	Bontempi	BD-31
Adson Toothed dissection forceps	Bontempi	BD-30
Surgical scalpel handle nº 4	Swann-Morton	4
Surgical scalpel blades nº 24	Swann-Morton	24	Ad libitum
Iris scissors- curved	Bontempi	FG-2
Periostotome P-24	Bontempi	718-24G
Intramuscular 23G sterile needles	Totclinic	23	Ad libitum
Goniometer
Latex gloves			Ad libitum
Gauze pads			Ad libitum
Non-Sterile surgical drape
Saw	EXAKT Advanced Technologies GmbH	EXAKT 312 Pathology Saw