Differences in Lateral Ankle Laxity Measured via Stress Ultrasonography in Individuals With Chronic Ankle Instability, Ankle Sprain Copers, and Healthy Individuals

STUDY DESIGN: Cross-sectional. OBJECTIVE: To use stress ultrasonography to measure the change in anterior talofibular ligament length during the simulated anterior drawer and ankle inversion stress tests. BACKGROUND: In approximately 30% of individuals, ankle sprains may eventually develop into chronic ankle instability (CAI) with recurrent symptoms. Individuals with CAI and those who have a history of ankle sprain (greater than 1 year prior) without chronic instability (copers) may or may not have mechanical laxity. METHODS: Sixty subjects (n = 60 ankles) were divided into 3 groups: (1) control subjects without ankle injury history (n = 20; mean +/- SD age, 24.8 +/- 4.8 years; height, 173.7 +/- 9.4 cm; mass, 77.2 +/- 19.5 kg), ankle sprain copers (n = 20; mean +/- SD age, 22.3 +/- 2.9 years; height, 172.8 +/- 11.3 cm; mass, 72.4 +/- 14.3 kg), and subjects with CAI (n = 20; mean +/- SD age, 23.5 +/- 4.2 years; height, 174.6 +/- 9.6 cm; mass, 74.8 +/- 17.3 kg). Ligament length change with the anterior drawer test and end range ankle inversion were calculated from ultrasound images. The Foot and Ankle Ability Measure was used to quantify self-reported function on activities of daily living and sports. RESULTS: The anterior drawer test resulted in length changes that were greater (F-2.57 = 6.2, P = .004) in the CAI (mean +/- SD length change, 15.6% +/- 15.1%; P = .006) and the coper groups (14.0% +/- 15.9%, P = .016) compared to the control group (1.3% +/- 10.7%); however, the length changes for the CAI and coper groups were not different (P = .93). Ankle inversion similarly resulted in greater ligament-length change (F-2.57 = 6.5, P = .003) in the CAI (25.3% +/- 15.5%, P = .003) and coper groups (20.2% +/- 19.6%, P = .039) compared to the control group (7.4% +/- 12.9%), with no difference in length change between the coper and CAI groups (P = .59). The CAI group had a lower score on the Foot and Ankle Ability Measure activities of daily living subscale (87.4% +/- 13.4%) and sports subscale (74.2% +/- 17.8%) compared to the control group (98.8% +/- 2.9% and 98.9% +/- 3.1%, respectively; P <.0001) and caper group (99.4% +/- 1.8% and 94.6% +/- 8.8%, respectively; P <.0001). CONCLUSION: Stress ultrasonography identified greater length changes of the anterior talofibular ligament ligament in both the coper and CAI groups compared to the control group. Only subjects with CAI had reductions in self-reported function. J Orthop Sports Phys Ther 2012;42(7):593-600, Epub 23 March 2012. doi:10.2519/jospt.2012.3923