Oiling an Arthritic Joint? Part 2
by Jose Fernando Syquia, MD, FPOASo how can it happen that there is statistically significant improvement with viscosupplementation but no clinically important improvement? De Moraes, et . al., in the 2014 issue of Acta Ortopedica Brasileira (Outcomes in Orthopedics and Traumatology: Translating Research into Practice) realized that translating research-focused evidence into practice may be challenging and misleading. The idea of a “minimally significant clinical difference” (or “minimum clinically important improvement”, as the AAOS put it) came about due to the finding that frequently identified statistical differences did not reflect clinical differences. An example that they gave in their report was on the use of platelet-rich plasma (PRP). Meta-analysis of patients who underwent application of PRP for certain orthopaedic problems reported a statistical reduction of pain (when compared with those who did not receive PRP) of up to -1.41. The question they posed was whether it was justifiable to give PRP if the maximum difference in pain score was just 1.41, considering that studies showed that differences above 3 points were those that resulted in relevant clinical differences. In short, the AAOS felt that statistical significance did not equate to clinical significance.
In 2014, the Osteoarthritis Research Society International (OARSI) reported that the benefit of viscosupplementation is uncertain for osteoarthritis of the knee due to the inconsistent conclusions of large studies.
On the other hand, Evanview, et.al., in a 2014 meta-analysis published in Clinical Orthopaedics and Related Research (Viscosupplementation for the Treatment of Osteoarthritis of the Knee) supported the use of hyaluronic acid injection for knee osteoarthritis. They reported that viscosupplementation offered benefits when compared to placebo in terms of function, pain, and patient global assessment, most notable at the 5 to 13-week post-injection period. According to Bannuru, et. al, in their article published in Osteoarthritis and Cartilage, the effects of hyaluronic acid injection are usually noted by 4 weeks, peak at 8 weeks, and can still be felt by 24 weeks.
A 2016 article from the American Medical Society for Sports Medicine published in the British Journal of Sports Medicine (AMSSM Scientific Statement Concerning Viscosupplementation Injections for Knee Osteoarthritis) recommended the use of viscosupplementation for patients above 60 years old with mild to moderate knee osteoarthritis. Their study showed that patients who received hyaluronic acid injection to their knees had a 15% chance of responding to treatment when compared to intra-articular steroid injection and an 11% chance of responding to treatment when compared to intra-articular placebo.
So, how do I advise my patients who ask about viscosupplementation – or, as they colloquially would say it, putting oil into their joint? First, I would tell them that the results, based on scientific literature, are inconclusive at best. I would then explain to them that the procedure is a bit expensive and they would have to decide whether it would be worth the cost. Finally, I tell them that although I have had the opportunity to inject a number of patients and see them improve, I have also operated on many patients who have had several injections that did not work for them.