Screening of Undiagnosed Increased Lateral Ankle Laxity Using Stress Ultrasonography

Background: Some patients with lateral ankle sprain (LAS) will experience chronic lateral ankle instability (CLAI). However, not all of those with residual increased lateral ankle laxity (ILAL) become symptomatic. There is a lack of evidence regarding the prevalence of undiagnosed ILAL in the general population.

Purpose: To evaluate the prevalence of undiagnosed ILAL with the use of stress ultrasonography (US) and to investigate the percentage of ankle sprain copers (ASCs) with ILAL.

Study design: Cross-sectional study; Level of evidence, 3.

Methods: The anterior talofibular ligament (ATFL) lengths in college students without diagnosis of CLAI were measured consecutively in stress and nonstress positions. The ATFL ratio was calculated as an indicator of lateral ankle laxity according to a previously reported method. The manual anterior drawer test was also performed. The Cumberland Ankle Instability Tool (CAIT) and Ankle Instability Instrument (AII) were used to assess subjective impairments related to CLAI. The correlation between the ATFL ratio and CAIT score was evaluated.

Results: A total of 207 ankles from 106 participants (mean age, 23.9 ± 2.2 years; male/female, 64/42) were included. Overall, 38 participants (35.8%; 50 ankles [24.2%]) were classified as having undiagnosed ILAL. Of the ankles with no history of LAS, 8% showed ILAL. Overall, 53 participants (50%) had a history of LAS and were all classified as ASCs. Of the 82 ankles from these ASCs, 40 (48.8%) were regarded as having undiagnosed ILAL. There was no correlation between the ATFL ratio and CAIT scores (r = -0.09, P = .414).

Conclusion: The prevalence of undiagnosed ILAL by stress US screening was approximately one-third in young adults. In this study, 48.8% of the ankles from ASCs showed ILAL.