Intra-articular pathology associated with isolated posterior cruciate ligament injury on MRI.

OBJECTIVE: Unlike with anterior cruciate ligament injury, little is known about the prevalence of intra-articular pathology associated with isolated posterior cruciate ligament (PCL) injury in the knee. The objectives of this study were to characterize and identify the frequency of meniscal tears and osteochondral injuries in these patients, and to see if management might be affected.

MATERIALS AND METHODS: Altogether, 48 knee MRI exams with isolated PCL tears were evaluated for the presence of: grade and location of PCL tear, meniscal tear, articular chondral lesion, bone bruise, and fracture. Comparisons between PCL tear grade and location, as well as mechanism of injury when known, with the presence of various intra-articular pathologies, were made using the chi-square or Fisher's exact test as appropriate.

RESULTS: In all, 69 % of isolated PCL tears occur in the midsubstance, 27 % proximally. Meniscal tears were seen in 25 % of knees, involving all segments of both menisci, except for the anterior horn medial meniscus. Altogether, 23 % had focal cartilage lesions, usually affecting the central third medial femoral condyle and medial trochlea, while 12.5 % of knees had fractures, and 48 % demonstrated bone bruises, usually involving the central to anterior tibiofemoral joint. The presence of a fracture (p = 0.0123) and proximal location of PCL tear (p = 0.0016) were both associated with the hyperextension mechanism of injury. There were no statistically significant associations between PCL tear grade and presence of intra-articular abnormality.

CONCLUSION: Potentially treatable meniscal tears and osteochondral injuries are relatively prevalent, and demonstrable on MRI in patients with isolated acute PCL injury of the knee.