Knee osteoarthritis: Should your patient opt for hyaluronic acid injection?

Our meta-analysis was not consistent with a previous meta-analysis of hyaluronic acid treatment with regard to pain relief and reduction of disability. This study¹⁵ revealed that hyaluronic acid has a therapeutic effect on osteoarthritis of the knee, specifically decreasing pain and disability. The analysis included 20 studies, but differed from ours in that it failed to control for between-group heterogeneity and used an original formula to derive mean differences in efficacy scores between hyaluronic acid and placebo. Each study in our meta-analysis used an identical method for reporting outcome scores. Our study also synthesized the original data values as reported in each original study.

In addition, our results have to be interpreted with attention to a large effect of saline injection, which were much greater than the expected effect of placebo. Calculated effect sizes demonstrated similar effects for both treatment and placebo groups, with no clustering that was different between groups ( FIGURE 2 ). Treatment and placebo groups showed equal response when evaluated for greatest effect.

Refocusing research

The effects of hyaluronic acid injection appear to be transient and offer only slight improvement for older patients with mild to advanced osteoarthritis. Attention should be given to other groups, including younger patients and patients with mild degenerative changes. These studies should attempt to better stratify patient groups to identify those who are most likely to benefit from intervention. In addition, there must be better reporting of treatment protocols and results will allow clinicians to make rational decisions regarding treatments.

Cost and side effects

Consider the degree of benefit and costs when making treatment decisions. The average treatment cost was approximately $900 in 2003.²¹ Obviously one issue is whether a patient’s insurance provider will pay for the treatment.

Side effects are uncommon, and complications with hyaluronic acid injections have been relatively mild.

A few cases of hyaluronic acid allergy have been reported,²² including sweating, paleness, feelings of pressure in the chest and stomach, skin turning blue, or a decrease in blood pressure.²²

Acknowledgments

The authors would like to thank Esra Akdeniz from the Statistical Consulting Center at the Pennsylvania State University for assistance with the methods for performing statistical meta-analysis.

CORRESPONDENCE
Jennifer M. Medina, 146 Recreation Building, University Park, PA 16802. E-mail: jmm322@psu.edu