Prevalence and Injury Patterns of CFL Injury in Chronic Lateral Ankle Instability: An Observational Cross-Sectional Study Using Ultrasound

The purpose of this paper is to assess the prevalence and injury patterns of the calcaneofibular ligament (CFL) in chronic lateral ankle instability (CAI) patients using ultrasound imaging. This retrospective study included 938 ankle ultrasound images from January 2016 to May 2018. The patients' demographic data and the injury pattern classified by the injury location and the remnant quality were recorded and correlated using t tests, Fisher's exact tests, and post hoc tests accordingly. Of the 938 CAI patients, CFL injury was found in 408/938 (44%). Among the 408 anterior talofibular ligament (ATFL) and CFL complex injury patients, 71/408 (17%) presented with a completely absorbed ATFL, whereas 13/71 (18%) presented with an absorbed CFL. The total CFL absorption proportion in all patients was relatively low (30/938 = 3%). Post hoc tests indicated a negative association between thickened ATFLs and complex injuries. In addition, a positive association existed between absorbed ATFLs and complex injuries as well as absorbed ATFLs and absorbed CFLs. Thus, the results indicated that total tearing and absorption injury patterns of the CFL in CAI are not common. Even when the ATFL is absorbed, only approximately one-fifth (13/71 = 18%) of CFLs require reconstruction, suggesting that it is unnecessary to routinely repair or reconstruct CFLs in all lateral ligament surgeries.