Increased ligament thickness in previously sprained ankles as measured by musculoskeletal ultrasound

Lateral ankle sprains are among the most common injuries in sport, with the anterior talofibular ligament (ATFL) most susceptible to damage. Although we understand that after a sprain, scar tissue forms within the ligament, little is known about the morphologic changes in a ligament after injury.

To examine whether morphologic differences exist in the thickness of the ATFL in healthy, coper, and unstable-ankle groups.

Cross-sectional study.

Laboratory.

A total of 80 National Collegiate Athletic Association Division I collegiate athletes (43 women, 37 men, age = 18.2 ± 1.1 years, height = 175.8 ± 11.1 cm, body mass = 75.0 ± 16.9 kg) participated in this study. They were categorized into the healthy, coper, or unstable group by history of ankle sprains and score on the Cumberland Ankle Instability Tool.

A musculoskeletal sonographic image of the ATFL was obtained from each ankle. Thickness of the ATFL was measured at the midpoint of the ligament between the attachments on the lateral malleolus and talus.

A group-by-limb interaction was evident (P = .038). The ATFLs of the injured limb for the coper group (2.20 ± 0.47 mm) and the injured limb for the unstable group (2.28 ± 0.53 mm) were thicker than the ATFL of the "injured" limb of the healthy group (1.95 ± 0.29 mm) at P = .015 and P = .015, respectively. No differences were seen in the uninjured limbs among groups.

Because ATFL thicknesses of the healthy group's uninjured ankles were similar, we contend that lasting morphologic changes occurred in those with a previous injury to the ankle. Similar differences were seen between the injured limbs of the coper and unstable groups, so there must be another explanation for the sensations of instability and the reinjuries in the unstable group.