The use of ultrasonography as an effective screening tool for chronic posterior cruciate ligament injuries

Abstract

Purpose We aimed to explore the applicability and validity of ultrasonography for diagnosing chronic posterior cruciate ligament (PCL) injuries. Methods PCL thickness was measured at 2 cm proximal to the tibia insertion site. Using the same ultrasonography image, the angle tangent to the PCL from the tibia insertion site was also measured. These data were analyzed by plotting the receiver operating curve (ROC), and the sensitivity and specificity were calculated according to the optimal cut-off point. Ultrasonography data from the PCLinjured knee were compared with those from the contralateral uninjured knee of the same patient. Results Twelve men and six women, with a mean age of 28.8 ± 14.0 years, were included in this study. The mean time from injury to medical examination was 10.0 ± 6.7 months. The mean thickness of the PCL was 8.1 ± 1.9 mm on the affected side and 5.8 ± 1.2 mm on the uninjured side, with the affected side being significantly thicker. ROC analysis revealed that the optimal cut-off value for the thickness of chronic PCL injuries was 6.5 mm (sensitivity 83.3%, specificity 77.8%, area under the curve [AUC] = 0.87). The optimal cut-off value for the angle was 20° (sensitivity 88.9%, specificity 94.4%, AUC = 0.96). Conclusion Ultrasonography is useful as a screening tool for chronic PCL injuries. The optimal cut-off point was 6.5 mm for thickness and 20° for angle. Level of evidence IV.