Do intra-articular hyaluronate injections help knee OA?

Effective management of pain from OA of the knee can be frustrating, for patient and clinician alike. When NSAID’s and physical therapy prove ineffective, we often turn to intra-articular injections of steroids. If they don’t work, intra-articular hyaluronic acid is sometimes considered. But just how effective is hyaluronic acid?

A recent study in the Annals of Rheumatic Disease looked at this question by randomizing over 300 knee OA patients to receive either hyaluronic acid or saline injections, every six months for two years. Their results should raise some caveats as well as some eyebrows when we’re assessing our patients with knee OA. Some key findings:

  • While hyaluronic acid did provide 20% better pain relief than placebo, it took two years to see this difference. So, hyaluronic acid injections require patience from our patients.
  • The rate of pain reduction when patients were treated with placebo injections was 66%. This high response rate probably reflects both a typical placebo response seen in many clinical studies along with an anti-inflammatory response elicited by the needle entering the joint space.
  • Repeated injections were used to obtain the favorable responses – five injections grouped together every six months, or a total of 20 injections over two years.

It is worth noting that a 2006 NEJM study showed oral glucosamine/chondroitin sulfate to be 25% more effective than an oral placebo (79 vs. 54%). Please be aware, though, that glucosamine and chondroitin sulfate are not FDA-approved for use in OA.  Head-to-head comparisons of intra-articular steroids and hyaluronic acid generally show no significant difference in efficacy, though the hyaluronic acid is much more expensive.

So, what is the practicing physician to do? There are no easy solutions to offer our OA patients. A range of therapies are available which are modestly more effective than placebo. Fostering appropriate expectations for what is possible is an important component of treatment. And, as is true in treating many chronic conditions, an empathetic ear and a sympathetic voice can augment the effectiveness of our humble therapeutic arsenal.

Treatment options for OA of the knee can be generally grouped into three categories.

  1. More cost-effective – acetaminophen, NSAIDs, physical therapy, weight loss where applicable, possibly low-dose narcotics, possibly steroid injections.
  2. Less cost-effective – hyaluronic acid injections, topical NSAIDs, topical capsaicin.
  3. The final step, when all else fails – hip replacement.

Richard Fleming, MD

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