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

• Published in: Orthopaedic journal of sports medicine Vol. 9; no. 11; p. 23259671211056305
• Main Authors: Yokoe, Takuji, Tajima, Takuya, Kawagoe, Shuichi, Yamaguchi, Nami, Morita, Yudai, Chosa, Etsuo
• Format: Journal Article
• Language: English
• Published: Los Angeles, CA SAGE Publications 01.11.2021; Sage Publications Ltd
• Subjects: Orthopedics; Sports medicine; Ultrasonic imaging; United States > US; anterior talofibular ligament; stress ultrasonography; generalized joint laxity; normative values; chronic lateral ankle instability; sex
• ISSN: 2325-9671; 2325-9671
• DOI: 10.1177/23259671211056305

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.