Sodium hyaluronate is a sterile, highly purified mixture that is chemically similar to the natural hyaluronan normally found in the joints. It acts as a lubricant and shock absorber, inhibiting pain mechanisms and priming the joint to make its own fluid. In the study of 602 patients, injections of sodium hyaluronate (Hyalgan®) reduced chronic pain by nearly 50% in patients with shoulder arthritis.

All of the patients in the study had previously tried nonsurgical clinical interventions, including physical therapy, at least one steroid injection, and oral pain medications. At the beginning of the trial, patients received shoulder x-rays to confirm the diagnosis of osteoarthritis (OA), and magnetic resonance imaging (MRI) to diagnose soft tissue and bony pathology or tears in the rotator cuff.

During the 6-month study, patients received either five injections of sodium hyaluronate, three injections of the drug followed by two saline injections, or five saline injections. Subjects were asked to record their level of pain on a scale of 1 to 100 (with 100 being the highest). All three groups began with an average baseline score of 65. Patients with OA who received five injections of sodium hyaluronate had significant improvements compared to patients who received placebo (P = .0124). Patients who received three injections also improved significantly compared to the control group (P = .0363). Patients who received saline alone also saw a decrease in pain to around 43 due to the placebo effect and possibly the therapeutic benefit of irrigating the joint, the researchers suggest.

The results were comparable to the 1998 study that led the US Food and Drug Administration (FDA) to approve Hyalgan for the treatment of knee pain. The FDA is currently reviewing the results in shoulder pain, says lead researcher Theodore Blaine, MD, assistant professor of orthopaedic surgery at Columbia University Medical Center and an attending surgeon at New York-Presbyterian Hospital. "The results of the trial were very encouraging, and we hope [they] will lead to this drug's approval as an effective therapy for thousands of suffering patients," Dr. Blaine says.

New treatment for shoulder pain?

"We have used sodium hyaluronate a little for shoulder pain and have seen exactly the same results that we see in the knee," says Kevin Stone, MD, an orthopaedic surgeon at the Stone Clinic in San Francisco, California. "About 30% of [people] seem to be super-responders, and a single injection or a series of injections stimulates more lubrication and less stiffness and pain, but we can't tell in advance who will be a super-responder and who will not," he tells CIAOMed.

Also, unlike COX-2 inhibitors and traditional NSAIDs, which have been linked to gastrointestinal problems, heart attack, and stroke, there are no side effects to this therapy, according to Dr. Stone. Therefore, he says, "there is no reason not to try it. There is no downside; we think joint lubrication is extremely helpful in diminishing symptoms of arthritis in patients."

Reference

1. Blaine TA, Skyhar MJ, Collins PC, et al. Double-blind, randomized trial of IA sodium hyaluronate (Hyalgan) for chronic shoulder pain. Presented at: 73rd Annual Meeting of the American Academy of Orthopaedic Surgeons; March 22–26, 2006; Chicago, Ill. Abstract 426.