High-Versus Low-BMI Differences in Therapeutic Response to Intra-Articular Hyaluronic Acid in Knee Osteoarthritis

Abstract

Background: Knee osteoarthritis is a leading cause of chronic pain and functional limitation, and intra-articular hyaluronic acid is widely used for symptom control; however, therapeutic response may vary by patient characteristics such as body mass index. Objective: To evaluate whether BMI modifies pain outcomes following intra-articular hyaluronic acid injection in patients with knee osteoarthritis. Methods: A cross-sectional observational study was conducted at Touhy Spine and Joint Health Center, Lahore, from April to September 2025. Adults aged 40–80 years with knee osteoarthritis were recruited and categorized into low-BMI (non-obese) and high-BMI (obese) groups. Pain was assessed using the WOMAC pain subscale at baseline and after injection, and pain improvement was compared between groups using independent t-tests with effect size estimation. Results: Among 126 participants, obese patients had higher baseline WOMAC pain scores and demonstrated smaller pain reductions after injection compared with non-obese patients. Mean WOMAC pain improvement was greater in the low-BMI group, and percentage pain improvement was also significantly higher, indicating a diminished therapeutic response among obese patients. Conclusion: BMI significantly influenced symptomatic response to intra-articular hyaluronic acid in knee osteoarthritis, with non-obese patients achieving greater pain relief than obese patients, supporting BMI-informed counseling and individualized treatment planning