Study Summary

90 patients undergoing primary arthroscopic anterior cruciate ligament (ACL) reconstruction were randomized to receive early hyaluronic acid (HA) injection on postoperative day 2, delayed hyaluronic acid injection at 2 months, or placebo saline injections at both time points. One patient in the delayed hyaluronic acid group was excluded due to postoperative donor-site infection, and two patients were lost to follow-up, resulting in 87 patients completing the study. The primary outcome of interest was the proportion of patients achieving a Lysholm score greater than 83, indicating good-to-excellent knee function. Secondary outcomes included pain intensity (VAS), knee range of motion, International Knee Documentation Committee (IKDC) score, Tegner activity score, health-related quality of life (EQ-5D-5L and EQ-VAS), and inflammatory markers. Outcomes were assessed at baseline, monthly up to 6 months, and at 12 months postoperatively. Overall, the results of the study revealed that early hyaluronic acid injection led to superior pain relief, faster functional recovery, and improved quality of life during the first 1–2 months after surgery. However, these benefits were not sustained at 6 or 12 months.