There are two major ligaments in the knee joint: the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL). By far, the ACL is injured or damaged more often than the PCL. Not as much is known about what happens when the PCL is torn.
A recent study in Germany tracked 181 patients with PCL tears who did not have surgery to repair the injury. They found that damage to the joint cartilage after a PCL tear is common. In fact, more than half of all patients with a PCL tear develop cartilage damage and arthritis after that.
After a PCL tear, there is a change in where the knee joint comes together during movement. A weak PCL causes more pressure on the inside edge of the knee. Higher loads and greater force act on the cartilage. The cartilage gets worn down and damaged.