A new meta-analysis of 29 randomized studies involving more than 4,500 patients with knee osteoarthritis (OA) found that intra-articular hyaluronic acid (HA) injections provided significant improvement in pain and function compared to saline injections.

The study, "US-Approved Intra-Articular Hyaluronic Acid Injections are Safe and Effective in Patients with Knee Osteoarthritis: Systematic Review and Meta-Analysis of Randomized, Saline-Controlled Trials," was published online this month in Clinical Medicine Insights: Arthritis and Musculoskeletal Disorders and included results from randomized peer-reviewed studies of six HA injection brands, with identical follow up between the treatment and control groups. The results are in contrast to the Rutjes et al (2012) paper that included data from many HA products which are not FDA approved and not available in the U.S.

"The findings of the meta-analysis are important but not unexpected. The safety data in the meta-analysis comes from studies that only used FDA-approved HAs. The data set is consistent with what I and many other physicians have clinically observed for many years – HAs have been found to be safe, can help relieve knee pain from osteoarthritis, and are appropriate treatment for people with mild to moderate forms of the disease," said Mark A. Snyder, MD, an orthopedic surgeon from the TriHealth Orthopedic and Spine Institute in Cincinnati, Ohio.

While neither HA or saline injections resulted in serious adverse events, researchers found very large treatment effects between four and 26 weeks for knee pain and function compared to pre- values, with standardized mean difference (SMD) values ranging from 1.07 to 1.37 (p<0.001). These changes represent approximately 50 percent improvement in pain and function from baseline with viscosupplementation. Additionally, improvements in knee pain and function with viscosupplementation were statistically superior compared to saline injections (p<0.001) for both. These findings differ with the analysis conducted this year by a U.S.-based orthopaedic physician society which also included products that were not FDA approved.

"Studies such as this are critical in helping physicians and patients make informed decisions," said Dr. Snyder. "Currently, there are limited treatment options available to healthy people with mild to moderate OA. Access to HA treatments is a great option for those who are seeking help in staying active. "

The review and meta-analysis were conducted by Larry Miller, PhD (Miller Scientific Consulting) and Jon Block, PhD (The Jon Block Group). The authors acknowledge that the study's findings have limitations. Their analysis did not include many subjects with end-stage knee OA or specify efficacy among the different types of HAs. The authors also noted that efficacy outcomes were inconsistent across studies and that there was evidence of publication bias in OA knee pain outcomes. There were no statistically significant differences between HA and saline controls for any safety outcome.

Osteoarthritis is a progressive disease that affects 27 million Americans. The most common joint to be affected by OA is the knee. Advancing age, previous joint trauma and misalignment, and genetic predisposition are all risk factors for having the disease, while obesity contributes to its progression. There is no cure, and treatment options are focused on the management of and maintaining function. Commonly prescribed non-surgical treatments for patients with symptomatic knee OA include weight loss, exercise, non-steroidal anti-inflammatory drugs (NSAIDs), corticosteroid injections, and HAs. Chronic use of NSAIDs and corticosteroids carries safety risks, especially for elderly patients and any patient with conditions such as heart disease or diabetes. Total replacement surgery is also considered an option when other treatment pathways are not successful.

Provided by Hyaluronic Acid Viscosupplementation Coalition