Effects of Hyaluronate Sodium on Pain and Physical Functioning in Osteoarthritis of the Knee

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Abstract
Background Intra-articular hyaluronate sodium is a relatively new therapy for the treatment of osteoarthritis of the knee. This randomized, double-blind clinical trial was conducted at a large primary care medical center to determine the impact of hyaluronate sodium vs conventional therapy on measures of pain, stiffness, and disability at rest and following functionally relevant walking and stepping activities. Methods A total of 120 patients (mean age, 67 years) with unilateral grades 1 to 3 medial compartment knee osteoarthritis were randomized to 1 of 4 treatment groups: group 1, 2 mL of hyaluronate sodium at a concentration of 10 mg/mL and placebo (100 mg of lactose); group 2, nonsteroidal anti-inflammatory drugs (NSAIDs) (75 mg of diclofenac and 200 µg of misoprostol) and hyaluronate sodium; group 3, NSAIDs and placebo (2 mL of isotonic sodium chloride solution [saline]); and group 4, placebo (lactose and saline). Intra-articular hyaluronate sodium or saline (2 mL) was administered once weekly over 3 weeks while NSAIDs or lactose were administered twice daily over 12 weeks. Main Outcome Measures (1) Western Ontario McMaster Universities Index (WOMAC) global measure of pain, stiffness, and disability; (2) visual analog scale (VAS) scores for pain at rest and following functional walking and stepping activities (self-paced walking and stepping); and (3) functional performance (exercise time, heart rate, and predicted maximum oxygen uptake) at baseline and weeks 4 and 12. Results At week 4, significant improvement in WOMAC scores for pain and disability and VAS score for resting pain was observed in groups 1 to 3 compared with baseline measures. Groups 1 and 2 showed significantly lower self-paced stepping pain, while no change was observed in group 4. At week 12, groups 1 to 3 showed significantly greater improvement in WOMAC pain subscale score and VAS score for resting pain; however, these differences did not vary from week 4. Following self-paced walking and stepping, groups 1 and 2 reported significantly less activity pain, while group 1 showed significantly faster self-paced walking and stepping test results. Groups 1 to 3 improved self-paced walking and stepping time at week 12 compared with baseline measures, while predicted maximum oxygen uptake was significantly higher in the hyaluronate sodium groups 1 and 2 at weeks 4 and 12 compared with baseline measures. Conclusions For resting pain relief, hyaluronate sodium seems to be as effective as NSAIDs. Further, for pain with physical activity and functional performance, hyaluronate sodium may be superior to placebo alone or NSAIDs alone.