Chronic ankle instability has no correlation with the number of ruptured ligaments in severe anterolateral sprain: a systematic review and meta-analysis

Purpose Despite being a significant public health problem, ankle sprains’ prognostic factors are largely unknown. This review aimed to systematically analyze the literature on acute ankle sprains to compare the prognosis of a combined anterior talofibular (ATFL) and calcaneofibular (CFL) ligaments rupture with an isolated ATFL rupture in terms of progression to chronic ankle instability and other clinical outcomes. Methods The databases for Pubmed, CENTRAL and Web of Science were searched. Clinical studies reporting the prognostic effect of combined ATFL-CFL rupture versus an isolated ATFL rupture in conservatively treated ankle sprains, with a minimum follow-up of 12 months, were eligible for inclusion. Only studies with a reliable diagnostic method for anterolateral ankle ligaments evaluation, namely ultrasonography, magnetic resonance imaging, arthrography or stress tenography, were included. The relative risk (RR), along with the 95% confidence interval (CI), was used to quantitatively analyze the main outcomes. Results Nine papers were selected for inclusion, of which five were suitable for quantitative analysis. None of them found a statistically significant correlation between ligament injury severity and progression to chronic instability. Concerning other clinical outcomes, three studies found a statistically significant correlation between a combined ligament injury and a worse clinical prognosis. From the quantitative analysis, the relative risk (RR) of chronic ankle instability in a single versus a combined ligament rupture showed no significant difference. Conclusion A significant statistical correlation between a combined ATFL-CFL rupture and chronic ankle instability, compared to an isolated ATFL rupture, was not found. There is, however, fair evidence showing a worse clinical outcome score in the combined ruptures, as well as a decreased return to full sports activities. The use of reliable and accessible diagnostic methods to determine the number of ruptured ligaments might have a role in managing severe ankle sprains. Level of evidence Level III.