MR-IMAGING OF THE POSTERIOR CRUCIATE LIGAMENT - NORMAL, ABNORMAL, ANDASSOCIATED INJURY PATTERNS

The posterior cruciate ligament (PCL) of the knee has received little attention in the radiology literature, but its importance in knee stab ility has come under close scrutiny in recent years, Unrepaired injury of the PCL can lead to chronic instability and early joint degenerati on. Three major mechanisms of trauma that in involves the PCL are post erior displacement of the tibia in a flexed knee, hyperextension, and rotation combined with an adduction or abduction force, The spectrum o f PCL injuries includes partial tear or intrasubstance injury, complet e ligamentous rupture, and avulsion of the PCL insertion site on the p osterior tibia, Associated injuries include injury of other ligaments, meniscal tear, bone injury, and joint effusion, PCL rupture is easily identified with magnetic resonance (MR) imaging by using simple signa l intensity and structural characteristics. Because clinical and arthr oscopic assessment of the PCL can be difficult, MR imaging can be valu able for evaluating the acutely injured knee when operative repair of the PCL is being considered.