Ultrasonographic examination of the normal and injured posterior cruciate ligament

Purpose. The purpose of the study was to determine the echogenicity and thickness of both the normal and injured posterior cruciate ligament (PCL). Methods. Eight patients with anterior cruciate ligament injury received ultrasonographic evaluation during arthroscopic examination. With the aid of the comet-tail artifact produced by the metal hook during arthroscopic examination, the normal PCL was located on sonograms. Thereafter, 11 patients with PCL injury were examined. In all subjects, the PCL thickness was measured at 2.0 cm proximal from posterior end of the distal PCL inserting onto the tibia. Results. The normal PCL was located just posterior to the posterior tibial intercondylar area. It was hypoechoic and was thickened proximally and tapered distally. The mean thickness of the injured PCL was 0.71 ± 0.12 cm, which was significantly (p < 0.05) greater than that of the normal ligament (0.52 ± 0.08 cm). Different appearances could be observed, including ligamental rupture and avulsion fracture of the tibial insertion of the PCL. Conclusions. The normal PCL appears on longitudinal sonograms as a hypoechoic fan-shape structure. Sonographic examination can identify different types of PCL lesions.