The correlation between clinical and ultrasound evaluation of anterior talofibular ligament and calcaneofibular ligament tears in athletes

BACKGROUND: The objectives of this study were to find correlation between the clinical and ultrasound grading in anterior talofibular ligament and calcaneofibular ligament tear, and to determine the sensitivity and specificity of the two stability tests among the athletes. Subsequently, we would like to propose a new grading criterion for an ultrasound examination.

METHODS: Two blinded assessors examined thirty-five patients with a history of recent lateral ankle sprain. The first assessor performed physical examination on the injured ankle by using the anterior drawer test and talar tilt test, and the second assessor performed dynamic and static ultrasound assessment for anterior talofibular ligament and calcaneofibular ligament. The clinical laxity grading and sonographic extent of ligamentous injury was graded into a three-point scale.

RESULTS: There was a moderate positive correlation between clinical test and ultrasound grading of anterior talofibular ligament and calcaneofibular ligament with Spearman's correlation coefficient values of 0.58 and 0.66 respectively. Clinical grading of anterior drawer test had 59.1% sensitivity (95% CI: 0.36-0.79) while ultrasound grading had 100.0% specificity (95% CI: 0.75-1.00), with positive likelihood ratio of 0.77 and negative likelihood ratio of 0.44 in detecting a complete (grade 3) anterior talofibular ligament tear (P<0.05). Meanwhile, the clinical grading of talar tilt test had 54.5% sensitivity (95% CI: 0.23-0.83) and ultrasound grading had 100.0% specificity (95% CI: 0.85-1.00), with positive likelihood ratio of 1.0 and negative likelihood ratio of 0.45 in detecting a complete grade 3 calcaneofibular ligament tear (P<0.05).

CONCLUSIONS: The dynamic ultrasound is recommended to determine the actual degree of disruption of the ligament especially when clinical grading under-grades the degree of tear. Grade 2 tears can vary from 10% tear to 90% tear causing the clinical correlation to become less strong. We recommend a new classification for ultrasound grading of grade 2 tears, which could result in a stronger correlation between clinical and ultrasound grading.