Study looks at why second ACL surgeries often fail

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Sports medicine specialists at Washington University School of Medicine in St. Louis are leading a national study analyzing why a second surgery to reconstruct a tear in the knee’s anterior cruciate ligament (ACL) carries a high risk of bad outcomes.

Rick Wright, MD (left), professor of orthopaedic surgery and co-chief of Washington University’s Sports Medicine Service, and Corey Gill, MD, instructor in orthopedic surgery, with a model of a knee joint/Robert Boston

More than 200,000 ACL reconstruction surgeries are performed each year in the United States, and 1 percent to 8 percent fail for some reason. Most of those patients then opt to have their knee ligament reconstructed a second time, but the failure rate on those subsequent surgeries is almost 14 percent.

The Washington University group has received a $2.6 million grant from the National Institute of Arthritis and Musculoskeletal and Skin Diseases and is leading dozens of surgeons across the nation in one of the largest orthopedic, multicenter studies ever conducted. The MARS study (Mutlicenter ACL Revision Study) is comparing surgical techniques and analyzing outcomes for patients undergoing ACL surgery to learn why a subsequent reconstruction is more likely to fail than an initial ACL repair.

“If I reconstruct the ACL in your knee, and you go back to sports, and three years later you pivot on a basketball court and tear it again, that subsequent surgery often does not have results equal to the original surgery,” says Rick W. Wright, MD, the MARS study’s principal investigator. “In a previous study, we found that the strongest predictor for a bad outcome after ACL surgery was whether that surgery was the initial reconstruction or a subsequent procedure.”

Wright, professor of orthopaedic surgery, co-chief of Washington University’s Sports Medicine Service and an orthopedic surgeon at Barnes-Jewish Hospital, has helped recruit 87 surgeons from 52 centers to participate in the MARS study. All are sports medicine specialists who are members of the American Orthopaedic Society for Sports Medicine. Surgeons involved in the study include both academic physicians and those in private practice.

During ACL reconstruction, surgeons sometimes replace the torn knee ligament with a ligament transplanted from a cadaver. In other cases, the surgeon will move a piece of the hamstring muscle or the patellar tendon and attach it in place of the torn ligament.

Wright and his colleagues are recruiting patients for the MARS study who have a second tear of the ACL. They plan to enroll 1,000 patients at the various centers around the country and follow them for at least two years to identify predictors of problems after surgery.

Surgeons will note the condition of the knee and how the original surgery was performed to see whether that predicts problems with a subsequent operation. They also will make note of the surgical technique initially used and whether the ACL graft used in the initial reconstruction came from a cadaver, from the hamstring muscle or from the patellar tendon.

Surgeons also will compare rehabilitation techniques and whether particular approaches are related to better, or worse, outcomes. Patients also will be surveyed about their knee function, the general state of their health and their quality of life before and after a second ACL surgery.

Those participating in the MARS study must be older than 12, but there is no upper age limit.

“By definition, most of the people in the study will be active,” Wright says. “ Most are athletes who want to continue to compete, but the study also is open to those who just need knee surgery so they can get back to work.”

The ACL plays a crucial role in our ability to cut, jump, twist and change directions. Even in people who don’t compete in sports, ACL tears are related to having a knee give out, and when that happens, says Wright, it can damage the knee’s meniscus, the rubbery disc that cushions the knee and keeps it steady. If the knee gives out it also can tear cartilage in the joint, contribute to arthritis and increase the risk that an individual will someday require total knee replacement surgery.

This study is supported by the National Institute of Arthritis and Musculoskeletal and Skin Diseases of the National Institutes of Health.

Washington University School of Medicine’s 2,100 employed and volunteer faculty physicians also are the medical staff of Barnes-Jewish and St. Louis Children’s hospitals. The School of Medicine is one of the leading medical research, teaching and patient care institutions in the nation, currently ranked fourth in the nation by U.S. News & World Report. Through its affiliations with Barnes-Jewish and St. Louis Children’s hospitals, the School of Medicine is linked to BJC HealthCare.