Tearing your ACL (Anterior Cruciate Ligament) can be a traumatic episode or a slow degeneration over time. Either way, there are only two reasonable choices: get an ACL repair surgery or just do Physical Therapy rehab exercises to try to stabilize the injured knee. It’s difficult to have a completely stabilized knee with a full ACL tear, because of what the ACL does within the knee joint.
The ACL is one of four major ligaments in the knee joint. The other three are the MCL (Medial Collateral Ligament), the LCL (Lateral Collateral Ligament), and the PCL (Posterior Collateral Ligament). The ACL is a strong ligament that prevents anterior translation of the tibia on the femur. In other words, when you squat or bend your knee in a closed-chain position (foot on the ground), the ACL prevents or limits the lower leg from moving forward.