Study Finds a Large Number of Young ACL Surgery Patients Need Second Knee Surgery at Later Date

New York, NY—May 1, 2015

Orthopedic surgeons are seeing an epidemic of anterior cruciate ligament injuries among young athletes, and a large number of patients who have surgery to reconstruct a torn ACL undergo a second knee operation later on, according to a study by researchers at Hospital for Special Surgery (HSS).

"This is the first study to evaluate, on a population level, the percentage of patients under age 21 who had subsequent ACL or non-ACL knee surgery following a primary anterior cruciate ligament reconstruction," said Emily Dodwell, MD, MPH, lead investigator and a pediatric orthopedic surgeon at Hospital for Special Surgery.

Compiling statistics from a New York State database, researchers found that eight percent of patients with a primary ACL reconstruction had another ACL surgery, and 14 percent had non-ACL knee surgery at a later date. 

Dr. Dodwell presented the study at the annual meeting of the Pediatric Orthopaedic Society of North America, which took place April 29 to May 2 in Georgia. The research was also presented at the annual meeting of the American Academy of Orthopaedic Surgeons last month.

Researchers identified patients under age 21 who had surgery for a torn ACL  between 1997 and 2010 using the Statewide Planning and Research Cooperative System (SPARCS) database for New York State. Patients were tracked for a subsequent ACL reconstruction or knee surgery for another injury, such as a torn meniscus, at a later date.

Investigators identified 23,912 primary pediatric ACL reconstructions in New York State. Out of those patients, 1,955 patients (8.2 percent) had a subsequent ACL reconstruction, and 3,341 patients (14 percent) had subsequent non-ACL knee surgery.

The median time lapse between the first and second ACL surgery was 1.6 years. The median time lapse between the first ACL reconstruction and surgery for another knee injury was 1.4 years.  The median length of follow-up for all patients was 6.7 years. 

Factors associated with needing a second ACL surgery included younger age at time of the first  ACL repair; being male; white race; private insurance; higher hospital ACL volume; and higher surgeon ACL volume. Factors associated with a second knee surgery for a non-ACL injury were younger age; being female; white race; private insurance; and higher hospital ACL volume.

Researchers noted that the study may underestimate the actual number of repeat ACL tears, as the database only included patients who underwent surgery, and did not include those who chose not to have additional surgery.

"The increasing rate of ACL injuries is concerning, although not surprising given greater participation in sports," Dr. Dodwell said. The study noted that children are starting sports at a younger age, playing for longer durations with greater intensity, and often concentrating on a single sport year round, resulting in overuse and acute injuries.

"For young people who have primary surgery to reconstruct a torn ACL, it is troubling that they have relatively high rates of subsequent ACL reconstruction or surgery for another knee injury.  Further research is needed to determine factors associated with subsequent injury and surgery so we can implement strategies to keep our youth safe while engaging in sports," Dr. Dodwell said.

To that end, Hospital for Special Surgery recently received a 2.76 million dollar grant from a private foundation to establish a program aimed at preventing ACL injuries in young athletes.

The HSS Sports Medicine Injury Prevention Program, a five-year endeavor, will begin by reviewing best practices based on the latest research. The hospital will then launch a comprehensive campaign to raise awareness, informing and educating the public and professionals on injury prevention.

The initial focus will be on preventing ACL tears, one of the most common knee injuries among young athletes. Those who participate in cutting and pivoting sports such basketball, soccer, football, skiing and lacrosse are most prone to an ACL injury.


About Hospital for Special Surgery
Hospital for Special Surgery (HSS) is the world’s largest academic medical center focused on musculoskeletal health. HSS is nationally ranked No. 1 in orthopedics and No. 2 in rheumatology by U.S. News & World Report (2016-2017), and is the first hospital in New York State to receive Magnet Recognition for Excellence in Nursing Service from the American Nurses Credentialing Center four consecutive times. HSS has one of the lowest infection rates in the country. HSS is an affiliate of Weill Cornell Medical College and as such all Hospital for Special Surgery medical staff are faculty of Weill Cornell. The hospital's research division is internationally recognized as a leader in the investigation of musculoskeletal and autoimmune diseases. Hospital for Special Surgery is located in New York City and online at


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