The knee joint is stabilized by four strong ligaments. The anterior cruciate ligament (ACL) passes diagonally in the middle of the knee, ensuring that the thigh and shin bone do not slide out of alignment during movement. ACL injury is one of the most common sports injuries of the knee joint and is generally repaired with ACL reconstruction surgery, where the torn ligament is replaced with a graft tendon. While this process is a very common and highly successful procedure, some may fail to achieve stability.
Failed ACL Reconstruction
Anterior cruciate ligament reconstruction failure may be due to the following problems:
Technical: This is the most common cause of failure and may involve incorrect drilling of a tunnel through the tibial or femoral bone for the attachment of the graft. This may cause increased stress on the graft or rubbing (impingement) of the graft on the surrounding edges of the bone. Other technical problems may include improper harvesting of the graft from the donor site, graft tensioning or inadequate graft fixation.
Biologic: This may be due to infection or graft rejection. Infection can be treated with irrigation and removal of damaged tissue of the joint as well as intravenous antibiotics.
Traumatic: This may occur due to early return to full activity, aggressive rehabilitation, trauma or non-compliance with activity restriction during the post-operative period.
Associated ligament laxity: Laxity of the other ligaments that support the knee has to be addressed either before or during the anterior cruciate ligament reconstruction to prevent undue stress on the reconstruction, and resultant failure.
Arthrofibrosis: Decreased post-operative range of motion of the knee called arthrofibrosis due to prolonged postoperative immobilization may be a cause for failed reconstruction.
A revision ACL reconstruction is considered after determining the exact cause for the initial failure. Repeat surgery is performed to improve graft stability and address other comorbidities such as infection and arthrofibrosis. Various alternative techniques, fixatives, and grafts are carefully considered for the revision reconstruction to correct failures of the primary surgery.