The posterior cruciate ligament (PCL) is a powerful ligament extending from the top-rear surface of the tibia to the bottom-front surface of the femur. The ligament prevents the knee joint from posterior instability. Update Date: 07/16/2007A.D.A.M. Editorial Team: Greg Juhn, M.T.P.W., David R. Eltz, Kelli A. Stacy. Previously reviewed by Kevin B. Freedman, MD, MSCE, Sports Medicine, Orthopaedic Specialists, Bryn Mawr, PA. Review provided by VeriMed Healthcare Network (5/31/2006).