Do Injections Ease Arthritis Knee Pain?

Osteoarthritis (OA) is a disabling disease that leads to severe morbidity and reduces physical activity in many Americans, contributing to other health problems like obesity, type-2 diabetes and cardiac disease. OA is one of the leading causes of disability in adults in the United States (Centers for Disease and Prevention 2009), and knee arthritis is ranked within the top 10 non-communicable diseases for reducing quality of life. The lifetime risk of suffering symptomatic knee OA is about 4 in every 9 people by age 70. Approximately 1 in 11 Americans is diagnosed with current symptomatic knee OA by age 60.

There is general consensus among health care providers that the initial treatment of knee OA should include weight loss and leg strengthening exercises. These two factors should be done with all patients with knee OA no matter what other treatments are used. However, using injections of medicine for treating knee arthritis is more controversial. These treatments include intra-articular steroids (IAS), hyaluronic acid (HA) injection and platelet-rich plasma injections.

Recently, colleagues and I evaluated if patients injected with HA reached a set recovery point in treatment. The OMERACT-OARSI criteria was developed in 2003 in order to standardize the assessment of which individuals in clinical trials for knee OA demonstrate a significant clinical response when comparing one treatment versus another treatment. When doing the study, we believed it was important to look at the potential for a person to meet pre-set goals of success than arbitrary goals determined post-treatment. We performed an analysis of the scientific literature for HA injections compared to IAS injections and placebo (no medicine) injections (IAP).  

Our results demonstrated evidence of small improvement but beneficial effect for the group of patients treated with HA injections compared to those treated with IAS or IAP injections with regard to pain and function. Even more important, we found that HA injection led to a 15 percent and 11 percent greater chance of achieving OMERACT-OARSI responder status than did IAS and IAP, respectively. IAS is often used for knee OA but like others, we found no added clinical benefit for IAS injection versus placebo injection. 

Our findings have prompted the American Medical Society for Sports Medicine to recommend viscosupplementation injections for knee osteoarthritis in those patients above the age of 60 based on high-quality evidence demonstrating benefits using the OMERACT-OARSI Responder Rating. The effectiveness of this treatment is not clear though for those under 60 years of age, but it seems likely it would be beneficial for people under 60 with knee OA.

Platelet-rich plasma (PRP) injections deserve mention for treatment of knee OA. PRP injections into the knee joint are a newer treatment in Sports Medicine and it has been shown to have both positive effects and in studies to have no effect on injury recovery. I have written on PRP in other blogs. Recently, a review of PRP for knee OA has shown an increase benefit when compared to HA injections. This is very promising treatment-wise. Currently, one of the problems is PRP is not covered by insurance for knee OA. From personal experience, I have found PRP more effective at treating OA than HA injections and HA injections more successful than IAS.

All in all though, HA injections are helpful and they should be considered as a part of the treatment of mild to moderate knee OA. PRP either with HA or alone may increase successful pain relief of knee OA, but would be an out of pocket expense from $500-$2000 per treatment. IAS should be reserved for synovitis associated with knee OA. And the number one thing to remember is that the most effective and safest treatment for knee OA is weight loss and strengthening exercises.