Bryan T. Kelly, MD, MBA President and Chief Executive Officer | Hospital for Special Surgery
Bryan T. Kelly, MD, MBA President and Chief Executive Officer | Hospital for Special Surgery
A recent preclinical study conducted by researchers at the Hospital for Special Surgery (HSS) suggests that earlier anterior cruciate ligament (ACL) reconstruction may reduce the risk of developing knee osteoarthritis. The findings were presented at the American Academy of Orthopaedic Surgeons 2025 Annual Meeting.
The study focused on immune cell activity following a knee injury, such as an ACL tear or rupture. After such injuries, immune cells move to lymph nodes and interact with other cells to regulate inflammatory responses in the joint. While this activity is crucial for healing, prolonged inflammation can lead to osteoarthritis.
“Orthopedic surgeons actively debate the optimal timing of ACL reconstruction after an ACL injury,” said Dr. Scott Rodeo, senior study author and Vice Chair of Orthopaedic Research at HSS. “The original thought for delaying surgery was to let inflammation resolve since operating on a highly inflamed knee can lead to postoperative stiffness, but how long to wait has been unclear.”
In their research, Dr. Rodeo and his team examined different timings for ACL reconstruction using preclinical models. Sixteen models underwent immediate surgery post-rupture, another sixteen had surgery one week after injury, while sixteen did not undergo surgery at all. Four weeks later, advanced techniques were used to measure immune cell counts in spleen and iliac lymph nodes draining from the knee.
Results showed increased immune cell populations in both surgical groups compared to those without surgery. However, delayed surgery resulted in significantly higher immune cell counts than immediate surgery.
Additionally, cartilage changes linked with osteoarthritis were more severe in models with delayed surgery compared to those with immediate intervention.
“Overall, our preclinical study suggests that immediate ACL reconstruction may lower the risk of developing knee arthritis," Dr. Rodeo noted. "These results inform ongoing human studies at HSS where we are evaluating the optimal timing of surgery and other factors affecting immune cells and inflammatory responses in ligament healing."
The study involved several authors including Thomas M. Li, MD; Julia Retzky, MD; Camila Carballo, PhD; Theresa T. Lu, MD; among others.
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