Summary

An anchor insertion position 5 mm from the articular surface and 10 mm proximal to the FOT, at an angle of 45° to the fibular axis and parallel to the fibular articular surface can provide a safe and effective method of repair.

Abstract

Background

Arthroscopic lateral ankle ligament repair (ALLR) is a widely surgical treatment for chronic ankle instability. Nevertheless, there is a paucity of reports on the safe and optimal anchor insertion position and direction. The purpose of this study was to investigate the optimal anchor insertion position and direction in ALLR using CT images.

Methods

The study included 29 ankles from 28 patients who underwent ALLR between 2018 and 2022, all of whom had postoperative CT scans. The study cohort consisted of 11 males and 17 females, with a mean age of 38.6 years (range 16-66 years). The surgical procedure was performed using a 30° arthroscope through the medial midline portal or the anteromedial portal. A single anchor was inserted through the accessory anterolateral portal in a parallel orientation to the fibular articular surface and at a 45° angle to the peroneal axis for repair. Postoperative CT axial images were used to measure the distance of the anchor insertion point from the fibular articular surface and the angle between the direction of anchor insertion and the joint surface. Sagittal images were used to measure the distance of the anchor insertion point from the fibular obscure tubercle (FOT) and the angle between the fibula axis and the direction of anchor insertion were measured.

Results

In the axial images, the mean distance of the anchor insertion point from the fibular articular surface was found to be 5.3 ± 1.6 mm, with an angle between the articular surface and the direction of anchor insertion of 13.3 ± 7.4°. In the sagittal images, the mean distance from the FOT to the anchor insertion point was found to be 8.9 ± 2.4 mm, with an angle between the fibular axis and the direction of anchor insertion of 48.6 ± 6.6°.

Discussion

Previous studies have reported that the center of the fibula attachment of the anterior talofibular ligament (ATFL) is located 4.3 mm from the inferior end of the fibular articular surface, with the ATFL width being approximately 10 mm. It has also been recommended to insert the anchor at an angle of less than 45° to the fibular axis and parallel to the lateral gutter plane. This study suggested that an anchor insertion position 5 mm from the articular surface and 10 mm proximal to the FOT, at a 45° angle to the fibular axis and parallel to the fibular articular surface, may represent a safe and effective method for repair, in close proximity to the anatomic attachment of the ATFL.