Summary

The Brostrom-Gould procedure appears to restore ATFL and CFL lengths during gait, however, dynamic functional testing reveals that in some cases kinematic differences between repaired and contralateral ankles may persist.

Abstract

Introduction

The lateral ankle ligament complex is the most frequently injured structure in athletes. Lateral ankle inversion sprains can cause laxity or tears in the anterior talofibular ligament (ATFL) and/or calcaneofibular ligament (CFL). As a result, up to 40% of patients with lateral ankle sprains suffer from chronic ankle instability (CAI). For those who fail conservative treatment, surgical intervention via Brostrom-Gould repair is an option that may potentially improve CAI. The purpose of this study was to determine the effectiveness of Brostrom-Gould repair in restoring functional stability of the ankle joint. It was hypothesized that after Brostrom-Gould repair, there would be no side-to-side differences in fibula-calcaneus rotations, fibula-talus rotations, and maximum lengths of the ATFL and CFL during the stance phase of gait.

Methods

The Bostrom-Gould procedure was performed to repair the ATFL and CFL on eight participants (1 M and 7 F; 23±7 years) with unilateral chronic ankle instability. Three to twenty-four months after surgery, three-dimensional ankle kinematics in the standing position and during the single-support phase of gait were determined using a validated volumetric model-based tracking process that matched subject-specific bone models, derived from CT, to biplane radiographs that were collected at 100 images per second. Coordinate systems were defined in the tibia, fibula, talus, and calcaneus of the right ankle of each patient and mirror imaged onto corresponding left ankle bones. Bone kinematics were determined for one static trial and four dynamic walking trials (from heel strike through toe-off) for both ankles of each participant. Side-to-side differences in mean kinematic curves (adduction, dorsiflexion, internal rotation) were indicated when the side-to-side differences were beyond ±1 standard deviation of the mean curve for each ankle. The origin and insertion sites for the ATFL and CFL were identified on each subject-specific bone model and used to determine ligament lengths during the dynamic walking trials. Paired t-tests were used to identify differences in maximum ligament lengths between repaired and contralateral ankles.

Results

In the static standing position, no significant differences were found between the repaired and contralateral ankles in terms of fibula-talus orientation (all p > .39) or fibula-calcaneus orientation (all p > .12). Side-to-side differences in fibula-talus and fibula-calcaneus kinematics were identified during the single-support phase of gait for two of eight subjects. During gait, the maximum lengths of the repaired and contralateral ATFL (14.3±2.5mm and 14.1±2.0mm, respectively (p=.74)) and CFL (24.3±2.8mm and 24.8±1.8mm, respectively (p=.27)) were not significantly different.

Discussion

In the standing position, the Brostrom-Gould procedure appeared to restore fibula-talus and fibula-calcaneus orientation. However in 2 of 8 patients, significant side-to-side differences in dynamic ankle kinematics were observed. This suggests that imaging during dynamic, functional movements may reveal differences in dynamic stability that are not apparent in static radiographs. The maximum ligament length results indicate that the Brostrom-Gould procedure restores maximal ATFL and CFL lengths during walking. A limitation of the current study is that only the relatively low-demand task of walking was studied; future studies will be necessary to investigate ankle stability during more demanding athletic activities.