A recent preclinical investigation by researchers at a leading orthopedic institute has revealed that prompt anterior cruciate ligament (ACL) reconstruction following an injury can significantly reduce immune cell activity, inflammation, and joint changes linked to knee osteoarthritis. The findings were presented at the American Academy of Orthopaedic Surgeons 2025 Annual Meeting, highlighting the importance of timely surgical intervention for optimal recovery.

The study explored the impact of different surgical timing strategies on immune response and cartilage health. Researchers discovered that immediate surgery led to less severe inflammatory responses and reduced signs of cartilage destruction compared to delayed procedures. These results challenge previous assumptions about waiting for inflammation to subside before operating and suggest that early intervention could be beneficial for preventing long-term joint damage.

Timely Surgical Intervention: A Path to Reduced Inflammation

Early surgical intervention appears to play a crucial role in managing post-injury immune responses. When an ACL tear occurs, immune cells migrate to lymph nodes, where they trigger inflammatory reactions in the joint. While this process is essential for healing, prolonged inflammation can contribute to the development of osteoarthritis. Immediate reconstruction seems to mitigate these risks by reducing immune cell activity and minimizing inflammation.

In the study, models that underwent immediate ACL reconstruction exhibited lower levels of immune cell activation compared to those with delayed surgery. This difference was particularly evident in the spleen and iliac lymph nodes, which drain from the knee. The researchers noted a significant increase in immune cell populations in both surgical groups relative to non-surgical controls, but the counts were notably higher in the delayed group. This suggests that postponing surgery may exacerbate immune responses and prolong inflammation, potentially leading to more severe joint changes over time.

Impact on Cartilage Health and Long-Term Joint Function

Beyond immune system effects, the timing of ACL reconstruction also influences cartilage integrity. Models that received immediate surgery showed less extensive cartilage destruction, indicating better preservation of joint function. Delayed surgical intervention, on the other hand, resulted in more pronounced cartilage damage, raising concerns about the long-term health of the knee joint.

Dr. Rodeo, senior author of the study, emphasized that chronic, unresolved inflammation is a key factor in the progression of arthritis after knee injuries. By intervening early, surgeons may be able to prevent this cycle of inflammation and cartilage degradation. The research team is now expanding their studies to include human subjects, using advanced imaging techniques like MRI and analyzing joint fluids and blood samples to further understand the role of immune cells and inflammation in ligament healing. These ongoing investigations aim to refine surgical protocols and improve patient outcomes, ensuring that future treatments are as effective as possible.