Fifteen years ago, the Food and Drug Administration (FDA) approved the use of an injection of hyaluronic acid for knee arthritis. It has been used ever since for the effective relief of arthritis pain in some carefully selected patients.
Now surgeons are turning their attention to the possible use of this same injection for ankle arthritis. Although it has not yet been approved for this type of use by the FDA, studies are starting to trickle in. So far, it looks like the procedure is well tolerated by patients with very few side effects or complications. But the question arises: does it work any better than a placebo injection with saline?
Surgeons from the Newton-Wellesley Hospital in Massachusetts set up a study to find out. They injected one group of patients with ankle arthritis using the hyaluronic acid. A second (control) group received the placebo injection of saline solution.
Hyaluronic acid is a substance naturally found in the body in small quantities. It seems to have a role in the multiplication of normal, healthy cartilage cells. Used as an injection into the joint, it is designed to rebuild the protective joint cartilage.
Patients were carefully selected for this study with limited inclusion criteria. Adults 18 years or older who had been formally diagnosed with ankle arthritis were included. They had to be willing to stop taking all pain meds during the study. Anyone who was pregnant, diabetic, or had circulation problems was not allowed to participate. Other exclusion criteria included the use of anticoagulant medication (prevents blood clotting) and the presence of sciatica, skin rash, plantar fasciitis, or ankle sprains.
Although the treatment with hyaluronic acid for joint osteoarthritis is usually three to five injections, patients in this study were only given a single injection (of either solution). Six and again 12 weeks after the injection, they were re-evaluated. Pain, motion, and function were the main before and after measures used to assess results.
They found that patients in both groups got much better by the end of 12 weeks. But there wasn't a significant difference between the groups to suggest one treatment was superior to the other. The equal results did show that at least for one injection, hyaluronic acid isn't any better than a placebo treatment.
The fact that everyone improved by the end of the study could demonstrate the natural process of healing, the effect of just inserting a needle through the skin, or it could have some other unknown meaning. The power of the placebo effect (patients expect to get better so they do) must be taken into consideration.
The authors did discuss why hyaluronic acid injections seem to work so well for some patients with knee osteoarthritis but these patients with ankle arthritis didn't get the same improvements. It's possible that because most ankle arthritis is the result of trauma (and knee arthritis is not), there is a difference in the response to hyaluronic acid. Ankle cartilage is also a lot stiffer, denser, and less elastic compared with knee cartilage. Maybe that makes a difference.
Further studies are needed with a series of injections to see if one just isn't enough to have an effect. The authors also suggest trying different hyaluronic products commercially available. It's possible that some formulations of the product work better than others. Different dosages need to be evaluated as well.
Until there is enough evidence that hyaluronic acid is an effective treatment for ankle arthritis, it is unlikely that insurance companies will reimburse for its use. With the high cost of this product, the authors recommend further study to find new types of nonsurgical treatment for ankle osteoarthritis that are cost effective and economical.
Reference: Henry DeGroot III, MD, et al. Intra-Articular Injection of Hyaluronic Acid is Not Superior to Saline Solution Injection for Ankle Arthritis. In The Journal of Bone and Joint Surgery. January 2012. Vol. 94A. No. 1. Pp. 2-8.