Study Identifies Steep Learning Curve for Surgeons Who Perform ACL Reconstructions

Patients who have their anterior cruciate ligament (ACL) reconstructed by surgeons who have performed less than 60 surgeries are roughly four to five times more likely to undergo a subsequent ACL reconstruction, according to a study by researchers at Hospital for Special Surgery. The study also showed that participating in a subspecialty orthopedic fellowship-training program did not improve the learning curve of young surgeons performing ACL reconstructions. The research was presented at the annual meeting of the American Academy of Orthopaedic Surgeons, held Feb 7-11.

“Conventional wisdom is that a trained surgeon should have excellent results once they have completed their training, but there is a learning curve to ACL surgery and what we have found is that in the early career volume or learning curve, surgeons’ outcomes are not as good as later outcomes for ACL reconstruction,” said Robert Marx, M.D., an orthopedic surgeon in the Sports Medicine and Shoulder Service at Hospital for Special Surgery (HSS) in New York City, who was a coauthor of the study. “Maybe we need to rethink how we train our surgeons in light of this.”

Stephen Lyman, Ph.D., director of Epidemiology and Biostatistics at HSS who presented the study, agrees. “We may not be training our sports medicine specialists well enough to perform this complex procedure if the learning curve is still this steep after finishing their fellowship,” he said.

The ACL is one of the most commonly injured ligaments of the knee, with approximately 100,000 ACL reconstructions performed each year in the United States. For years, doctors have known that outcomes in surgery are related to volume. For example, the more ACL reconstructions a surgeon performs, the more proficient they become with fewer patients having to undergo a re-operation. But until this study, doctors hadn’t investigated what the learning curve actually looked like. “The question was, on the upswing, how long does it take for you to become proficient?” said Dr. Marx. In addition, in recent years, an increasing number of doctors have pursued subspecialty sports medicine fellowship training programs after their orthopedic surgery training, and little is known about how these programs impact the learning curve of ACL reconstruction.

To fill these two knowledge gaps, HSS investigators turned to a database from the New York State Department of Health that includes information on all hospital admissions and ambulatory surgical procedures within the state of the New York. They identified all ACL reconstructions performed between 1997 and 2006 by surgeons who performed their first ACL reconstruction in 1997 or later. They then examined medical records to determine which patients had subsequent ACL surgery. The investigators controlled for case-mix factors, such as age, sex, insurance type, comorbidities and concomitant surgery.

The researchers identified 12,778 ACL reconstructions performed by 320 surgeons during the study period. They then compared the likelihood that a patient would have a subsequent ACL reconstruction if they had the procedure after the surgeon had performed 150 cases versus if the patient fell in the first 10 cases of a surgeon’s career, between 11 and 60 cases, between 61 and 120, or between 121 and 150. “For several non-orthopedic surgical procedures 10 cases are considered necessary to obtain clinical competence,” said Dr. Lyman.