Efficiency of knee ultrasound for diagnosing anterior cruciate ligament and posterior cruciate ligament injuries: a systematic review and meta-analysis

Objective: To evaluate the diagnostic performance of knee ultrasound for anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) injuries. Materials and methods: PubMed and EMBASE databases were searched for diagnostic accuracy studies that used ultrasound for diagnosing ACL and PCL injuries. Bivariate and hierarchical summary receiver operating characteristic modeling was used to evaluate diagnostic performance. Subgroup analysis was performed by assessing studies conducted using the ultrasound technique (functional ultrasound versus conventional ultrasound) for diagnosing ACL injury. We performed meta-regression analyses for a potential source of heterogeneity. Results: Eleven (938 ultrasound/878 patients) and six articles (281 ultrasound/237 patients) were included for ACL and PCL injuries respectively. The summary sensitivity, summary specificity, and area under the hierarchical summary receiver operating characteristic for ACL and PCL injuries were 0.88 (95% confidence interval [CI], 0.81–0.93) and 0.99 (95% CI, 0.49–1.00), 0.96 (95% CI, 0.91–0.98) and 0.99 (95% CI, 0.73–1.00), and 0.97 (95% CI, 0.96–0.98) and 1.00 (95% CI, 0.99–1.00) respectively. In subgroup analysis, there was no significant difference between sensitivity (p = 0.63) and specificity (p = 0.72) of functional and conventional ultrasound. Among the various potential covariates, patient enrollment, patient position, and ultrasound performer were associated with heterogeneity in terms of sensitivity, and proportion of the ACL injury was associated with heterogeneity in terms of specificity. Conclusion: Knee ultrasound demonstrates high diagnostic performance for ACL and PCL injuries, particularly when performed by experienced musculoskeletal radiologists. Future prospective studies to compare the cost- and time-effectiveness between ultrasound and magnetic resonance imaging and to determine the optimal ultrasound parameters are warranted.