The Ratio of Stress to Nonstress Anterior Talofibular Ligament Length on Ultrasonography: Normative Values

Abstract

Background: Stress ultrasonography (US) has been shown to be a valid procedure for evaluating chronic anterior talofibular ligament (ATFL) injury. The ratio of stress/nonstress ATFL length (ATFL ratio) as measured on US is clinically useful; however, there are no published normative data concerning this ratio. Purpose: To report a normative value of the ATFL ratio on US and evaluate the relationships between sex, generalized joint laxity (GJL), and the grade of anterior drawer test (ADT). Study Design: Cross-sectional study; Level of evidence, 3. Methods: The ATFL lengths were prospectively measured in the stress and nonstress positions (manual maximal anterior drawer position) for participants with noninjured ankles from March 2020 to March 2021. GJL was defined as a Beighton score ≥4. A manual ADT was also performed. The ATFL ratio was calculated, and the relationships between sex, GJL, and ADT grade were evaluated. Results: A total of 333 ankles in 184 participants (mean age, 24.5 ± 2.7 years; range, 20-33 years) were eligible for the analysis. GJL was found in 69 ankles (20.7%). The mean ATFL ratio was 1.08 ± 0.04 (95% CI, 1.08-1.09; range, 1.01-1.24), and there was a significant difference between male (1.07 ± 0.04; 95% CI, 1.07-1.08; range, 1.02-1.23) and female (1.09 ± 0.04; 95% CI, 1.08-1.10; range, 1.01-1.24) ankles ( P = .001). In male ankles, the ATFL ratio was significantly greater in participants with GJL (1.11 ± 0.06 vs 1.07 ± 0.03; P = .02) or a higher grade of ADT (grade 2 vs grade 1: 1.11 ± 0.06 vs 1.07 ± 0.03, P = .002). These findings were not observed in female ankles. Conclusion: The normative value of the ATFL ratio on stress US was 1.07 ± 0.04 in men and 1.09 ± 0.04 in women. The ATFL ratio was affected by the presence of GJL in men but not in women. These findings will be useful for future studies seeking to establish the cutoff value of the ATFL ratio for diagnosing chronic lateral ankle stability on stress US.

Association between the Beighton Score and Stress Ultrasonographic Findings of the Anterior Talofibular Ligament in Healthy Young Women: A Cross-Sectional Study

“…The assessment of the BS and manual anterior drawer test (ADT) were performed by a senior orthopedic surgeon prior to the US examination. US pictures of the ankle were obtained in the nonstress position (resting position) and the stress position (manual maximal internal rotation), as reported by Yokoe et al [ 13 ]. When bilateral ankles did not meet the exclusion criteria, the dominant ankle was evaluated and included in the study.…”

“…US pictures were obtained with an ALOKA ARIETTA 850 US apparatus (HITACHI, Tokyo, Japan) using a linear probe (L64 probe, 18–5 MHz). The stress US procedure was reported previously [ 13 ]. US pictures were taken in two positions: the resting position (nonstress ATFL) and the manual maximal internal rotation position (stress ATFL) ( Figure 2 ).…”

“…In the shoulder joint, Whitehead et al reported a poor correlation between the BS and specific measures of shoulder joint laxity [ 11 ]. In addition, compared with other joints, there is a lack of studies investigating the effect of GJL on the incidence of ankle injuries, including ankle sprains and CLAI [ 12 , 13 ].…”

“…Song et al evaluated the effect of GJL on the US findings of ATFL, reporting that the ATFL lengths on US in both stress and nonstress positions were significantly longer in the high-BS group (≥5) than in the low-BS group (<5) ( p < 0.001) [ 12 ]. In contrast, Yokoe et al reported that the influence of GJL on lateral ankle laxity may differ by sex based on their evaluation of the ATFL ratio (ratio of stress to nonstress ATFL length) on stress US [ 13 ]. They also found that the normal value of the ATFL ratio was significantly greater in healthy ankles of the female subjects than in male subjects (1.09 ± 0.04 vs. ± 1.07 ± 0.04, p = 0.001).…”

“…They also found that the normal value of the ATFL ratio was significantly greater in healthy ankles of the female subjects than in male subjects (1.09 ± 0.04 vs. ± 1.07 ± 0.04, p = 0.001). Given that young women tend to have greater laxity of the ankle joint and a higher BS than young men [ 2 , 13 ], the influence of GJL on lateral ankle laxity may not be significant in young women. Therefore, a higher cut-off value of the BS may be rational when comparing US findings of the ATFL between high- and low-BS groups of young women in order to clarify the influence of GJL on native lateral ankle laxity.…”