Summary

Relationship between lateral ankle laxity and generalized joint laxity in young patients with healthy ankles

Abstract

Background

Lateral ankle sprain (LAS) is one of the most common musculoskeletal injuries in the general population as well as in athletes. Previous studies have reported a number of risk factors for LAS and chronic lateral ankle instability (CLAI). However, there is a lack of evidence regarding the influence of GJL on the occurrence of LAS or CLAI. The purpose of this study was to evaluate the relationship between lateral ankle laxity and GJL in subjects with healthy ankles by using stress ultrasonography (US).

Methods

Healthy volunteers > 18 years old were prospectively recruited from March 2020. Exclusion criteria included a diagnosis of CLAI, a history of recurrent ankle sprains, a primary LAS within 12 months at the time of recruitment, prior surgical intervention to the foot and ankle, osteoarthritis of the ankle, inflammatory arthritis, and Ehlers-Danlos or Marfan syndrome. The GJL was assessed using the Beighton score, and was defined as scores of >4. US images of the ankle were obtained to measure anterior talofibular ligament (ATFL) length as a linear distance from the origin to the insertion of ATFL. The ATFL length was measured in two positions; the nonstress position and the stress position according to the modified procedure by Lee et al. The ATFL ratio (stress ÷ nonstress ATFL) was calculated as an indicator of lateral ankle laxity. US evaluation was performed by a certified orthopaedic surgeon who was blinded to patient’s Beighton score. Statistical analyses were performed to evaluate the relationship between the ATFL ratio and GJL. Student t test or Mann-Whitney U test was conducted to compare continuous data. The chi-square test or Fisher exact test was used to compare categorial data. The threshold of significance was set at p < 0.05.

Results

A total of 333 ankles of 198 subjects were finally included in this study. There were 169 ankles of 96 males and 164 ankles of 88 females. The mean age was 24.5 ± 2.7 years (range, 20-33 years). Sixty-nine ankles (20.7%) were from subjects with GJL. There was a significant difference in the prevalence of GJL between male and female ankles (10.7% vs. 31.1%, p < 0.001). The ATFL ratio in male ankles was 1.07 ± 0.04 (95% CI, 1.07-1.08) while that in female ankles was 1.09 ± 0.04 (95% CI, 1.08-1.10). There was a significant difference in the ATFL ratio between male and female ankles (p = 0.001). In comparison of the ATFL ratio between ankles with and without GJL, there was a significant difference in male ankles (1.11 ± 0.06 vs. 1.07 ± 0.03, p = 0.02) while there was no significant difference in female ankles (1.10 ± 0.05 vs. 1.09 ± 0.04, p = 0.24).

Conclusions

The ATFL ratio was affected by the presence of GJL in young men but not in young women. The present study suggests that the clinical significance of GJL on lateral ankle laxity may differ by sex.