It takes many patients up to a year or more to return to a normal walking pattern after ACL repair. Researchers aren't sure why there's such a slow return. It could be patients change the way they walk early on to avoid pain. Then the pattern is hard to break.
There may be slight changes in how the knee functions as a result of the surgery. Most ACL repairs are done with donor tendon from either the patellar tendon or the hamstring tendon. Problems with the donor site can make a difference.
A recent study from Australia found slight changes in knee motion based on the type of ACL graft used. With the hamstring tendon graft the knee had less knee extension when walking. Patients with patellar tendon grafts had less knee flexion.
Check with your doctor and physical therapist for their assessments. Watching you walk, measuring your motion, and checking the internal movements of the joint may help them
pinpoint the problem and a solution.