Twenty years ago a ruptured or torn anterior cruciate ligament was stitched back together. This is called a primary repair. The patient was immobilized in a cast or brace. Weight-bearing wasn't allowed for four weeks after surgery. After that, the patient followed a long rehab program.
There have been many changes in treatment since that time. For one thing the torn ligament is no longer just repaired. Now it is reconstructed using a tendon graft from another part of the knee. Open incisions have been replaced with arthroscopic surgery using tiny and sometimes only one incision.
These new methods mean there is less scarring, less trauma to the joint, and less damage to the surrounding soft tissues. As a result the patient is able to put weight on the leg immediately. Range of motion and strengthening are started right away too. The patient is allowed to move along in the exercise program as fast as he or she can tolerate.
Twenty years ago getting back on the playing field after an ACL repair wasn't always possible. Rehab and recovery often took a full year. Over time activities that involved pivoting, cutting, or sidestepping could be resumed after 9 months or so. Today with the accelerated rehab program, top athletes can return to full sports six months later.