A preclinical study from New York City-based Hospital for Special Surgery found that earlier anterior cruciate ligament reconstruction can lead to lower immune cell activity, less inflammation and fewer joint changes associated with knee osteoarthritis.
After a knee injury, immune cells go to lymph nodes to support and regulate inflammatory responses in the joint, according to a March 12 news release. But prolonged immune cell activity can promote osteoarthritis.
Researchers used preclinical models of ACL reconstruction to assess outcomes in surgery timing. Sixteen models had immediate reconstruction after ACL rupture, 16 underwent surgery a week after injury, and 16 had no surgery. After a month, researchers identified and measured the number of immune cells present in the spleen and iliac lymph nodes that drain from the knee.
Investigators saw an increase in several immune cell populations in the two surgical groups compared to the group that didn’t have surgery. Immune cell counts were also significantly higher in the models with immediate surgery compared to delayed surgery.
“Overall, our preclinical study suggests that immediate ACL reconstruction may lower the risk of developing knee arthritis, tying in with existing studies showing that chronic, unresolved inflammation leads to progressive arthritis after knee injury,” Scott Rodeo, MD, said in the release. “These results inform ongoing human studies at HSS in which we are evaluating the optimal timing of surgery and other factors that affect the role of immune cells and inflammatory responses in ligament healing. In these studies, we are evaluating changes in immune cells and inflammation in lymph nodes using magnetic resonance imaging, joint fluids and blood.”
