News Release

New study may identify risk factors for ACL re-injury

Peer-Reviewed Publication

American Orthopaedic Society for Sports Medicine

SEATTLE, WA – Re-tearing a repaired knee Anterior Cruciate Ligament (ACL) happens all too frequently, however a recent study being presented today at the American Orthopaedic Society for Sports Medicine's (AOSSM) Annual Meeting suggests that identification and patient education regarding modifiable risk factors may minimize the chance of a future ACL tear.

"Our research suggests that a few risk factors such as, age, activity level and type of graft utilized may point to the possibility of re-injury," said lead author, Christopher C. Kaeding, MD of the Ohio State University. "However, with better education about adjustments that can be made, based on these risk factors, patients may be able to minimize re-tears."

Kaeding and his team analyzed data from 2,695 patients through the MOON ACL injury database from 2002-2008. All patients had a primary ACL reconstruction with no history of contralateral knee surgery. Graft type, age, Mark score, sport played after surgery, sex, smoking status, meniscal tear status and Body Mass Index (BMI) were identified as criteria for inclusion into the study.

In the results, 116/2695 (4.3%) had a graft re-tear on the same side of the body and 97/2695 (3.6%) had a re-tear on the opposite side. The odds of re-tearing the same ACL, decreased by nine percent for each year of increased age. The odds of re-tear on the opposite ACL, decreased by four percent for every year of increased age.

"The study highlights that younger age, higher activity levels at time of injury and what type of graft used (allograft) may increase risk of same side ACL injury within two years. With individuals having higher activity levels and lower age re-tears on the opposite leg were more prominent," said Kaeding. "Physicians and physical therapists need to better educate our patients about continued neuro-muscular training even after the immediate rehabilitation process has ended to help prevent future tears."


The American Orthopaedic Society for Sports Medicine (AOSSM) is a world leader in sports medicine education, research, communication and fellowship, and includes national and international orthopaedic sports medicine leaders. The Society works closely with many other sports medicine specialists, including athletic trainers, physical therapists, family physicians, and others to improve the identification, prevention, treatment, and rehabilitation of sports injuries. AOSSM is also a founding partner of the STOP Sports Injuries campaign to prevent overuse and traumatic injuries in kids. For more information on AOSSM or the STOP Sports Injuries campaign, visit or

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