Reconstruction of the posterior cruciate ligament of the knee: anatomic, isometric, and tensioning considerations

Isolated injuries to the posterior cruciate ligament (PCL) are only now being recognized for their severity and their potential repercussions upon function of the knee. As more long term follow up studies of patients with untreated isolated PCL injuries are reported, the sequelae of this injury are being described. The previously held belief that isolated PCL injuries are relatively innocuous and require only conservative treatment is now being questioned. The posterior cruciate ligament is a complex anatomical structure that does not appear to demonstrate the isometric characteristics of its counterpart in the knee, the anterior cruciate ligament. Rather, it consists predominately of a nonisometric anterior bundle that resists posterior displacement of the tibia throughout the majority of knee range of motion. Changes in fiber-bundle length during knee motion appear to be most affected by changes in the femoral attachment site of the PCL graft. When reconstruction of the PCL is being considered, the anterior femoral location should be selected, the graft should be tensioned at ninety degrees of knee flexion, and a anterior tibial force should be applied prior to final graft fixation.