Inside each knee, there are two very strong ligaments providing stability to the joint. They are:
- Anterior cruciate ligament (ACL)
- Posterior cruciate ligament (PCL)
Tears of these ligaments can occur following significant trauma to the joint, often sustained during participation in sporting activities. However, this is not always the case and tears to the cruciate ligaments can occur after any kind of injury. The ACL is much more commonly damaged than the PCL.