Reasons for ACL Revision Surgery
An ACL reconstruction is one of the most common surgical procedures in orthopaedic surgey. Although only 10% of grafts fail, this is still a large number of cases. There can be many reasons for an ACL reconstruction failure.
The most common reason for an ACL graft to fail is due to technical issues with the original surgery. An ACL reconstruction is very technical and it is well recognized that surgeons who perform more of these procedures have improved outcomes. However, the majority of ACL reconstructions performed in the United States are performed by surgeons who perform ten (10) or less each year. For that reason, misplaced graft reconstruction tunnels are still a very common cause of an ACL reconstruction failure. This can be due to placement being too posterior on the tibia, which results in a central graft that does not control rotation, or too anterior placement on the femur, which can result in the graft stretching out as knee flexion returns.
The second most common cause of ACL reconstruction failure is due to untreated secondary instabilities. This could include a posterolateral corner injury, a meniscal root detachment, or a lack of the posterior horn of the medial meniscus. It is well recognized that a deficiency of these areas, and other areas to include an unrecognized PCL injury, medial knee injury, alignment issues in patients who have arthritis and other issues, are also common causes of ACL reconstruction failures. For this reason, the work-up for an ACL revision surgery must include evaluation of the secondary restraints of the knee and the integrity of the posterior horn of the medial meniscus.
Traumatic reinjuries also can occur, but in general are not felt to be the most common cause of ACL graft failure. In this circumstance, an athlete sustains a reinjury to their knee with the ACL graft being torn. While less common, athletes in this circumstance may have improved overall outcomes with an ACL revision surgery
Another important issue to evaluate for ACL reconstruction graft failures from ACL knee surgery is biologic issues. Literature has reported that patients who are less than 25 years of age have a much higher risk of ACL graft failure with an allograft reconstruction. In addition, a small number of patients may have their own grafts not completely heal and tear over time. Reasons for early allograft failure could include an immune response and lack of graft incorporation, a too early return back to high level activities prior to graft incorporation or issues with the graft itself to include unrecognized tearing within the graft or use of irradiation to sterilize the graft (which has been shown to increase the risk of graft failure).