If you have not had your surgeon re-evaluate your knee, now would be a good time for a follow-up visit. There may be a simple explanation for the pain you are experiencing. Or perhaps your rehab program needs tweaking a bit.
The surgeon will examine your knee structures, motion, and strength. The graft site will be included in the exam, too. Some of the possible causes of chronic knee pain after ACL reconstruction depend on the type of graft you had.
Anterior knee pain does occur in patients with bone-patellar tendon-bone grafts taken from the front of the knee. Any kind of pressure (e.g., kneeling) along that area can cause pain. Scar tissue and adhesions pulling on the soft tissue structures can occur with either kind of graft.
Studies show that ACL reconstruction can stabilize the joint. But it doesn't always restore normal joint kinematics (motion). Even small changes in the angle, tilt, or rotation of the patella (knee cap) can result in how the patella moves against the femur.
Altered tracking motion of the patella up and down over the femur can lead to a shift in cartilage contact. Pain might be the first indication that something isn't line up straight or moving correctly. Now is the time to identify the problem and change it if possible before degenerative joint changes occur.