Evaluating Outcomes of ACL Reconstruction

    An injury to the anterior cruciate ligament (ACL) is not without consequences: Research has shown there is about a 50% chance of developing osteoarthritis of the knee by 25 years after the injury.

    ACL reconstruction does not seem to alter this trajectory, and what’s more, surgeons have not been able to reliably predict who will and who won’t develop osteoarthritis.

    But that may be changing, according to Brian R. Wolf, MD, an orthopaedic surgeon from the University of Iowa in Iowa City, thanks to data from the Multicenter Orthopaedic Outcome Network, or MOON Group.

    Dr. Wolf participates in the MOON Group, and he said the group’s goal is to develop a prospective cohort of data on ACL reconstruction patients that will allow the clinicians involved to analyze risk factors for success, failure, and progression to osteoarthritis. So far, the group has data on about 3,200 ACL reconstructions.

    In a presentation for The Athlete’s Knee, a recent 1-day meeting co-sponsored by the International Congress for Joint Reconstruction and the Mid-America Orthopaedic Association, Dr. Wolf shared data from the vast MOON Group database showing predictors of poor outcomes at 6 years following ACL reconstruction. He focused on the Marx Activity Score and the KOOS subscale for knee-related quality of life.

    Data from the Marx Activity Score show that activity levels decrease at 2 years after ACL reconstruction, and then decrease further at 6 years. Predictors of poor outcomes include:

    • Revision ACL reconstruction
    • Grade 3-4 cartilage lesions on the medial femoral condyle
    • Smoker
    • Female

    According to the KOOS quality of life subscale, patients who undergo an ACL reconstruction have dramatically improved function at 2 years, which is maintained from 2 to 6 years. Dr. Wolf noted, however, that this improvement doesn’t mean the patients return to normal function. Predictors of poor outcomes include:

    • Revision ACL reconstruction
    • Allograft used for the primary reconstruction
    • Tear of the medial or lateral meniscus
    • Grade 3-4 cartilage injuries
    • Smoker
    • Higher BMI
    • Lower level of education

    Dr. Wolf said the KOOS results mirror the results he and his MOON Group colleagues have seen with the International Knee Documentation Committee (IDKC) score.

    The risk of additional surgery after the primary ACL reconstruction is 19% at 6 years, Dr. Wolf said, with use of allograft and younger age predicting this outcome.

    In addition, the risk of reinjuring the same ACL is 4.4%, and the risk of injuring the contralateral ACL is 3.5%. Patients with an allograft are at 5 times greater risk for reinjury than those who receive a bone-patellar tendon-bone autograft, as are younger, more active patients.

    Meniscus tears often occur with ACL tears, and when the meniscus is repaired at the same time as the ACL reconstruction, there is a 14% failure rate at 6 years, Dr. Wolf said. The reason this occurs is unclear.

    A meniscus tear that does not need to be repaired or debrided and is left in situ at the time of the ACL fares much better: 98% of lateral and 94% of medial tears do not require surgery later. Predictors of surgery include younger age and tears of 10 mm or more.

    The risk for infection after ACL reconstruction is low, Dr. Wolf said, at 0.8%, with diabetes and the use of a graft other than bone-patellar tendon-bone predicting a greater risk of infection.

    Finally, Dr. Wolf addressed the issue of cost and value. He recently published research showing that ACL reconstruction added 5.3 quality-adjusted life years at 6 years following surgery. That’s more than many other orthopaedic surgeries, including rotator cuff repair and total hip and total knee arthroplasty.

    Research has also shown that ACL reconstruction is more cost-effective when compared with rehabilitation alone.

    Click the image above to watch Dr. Wolf’s presentation.