First, remember that OA of a joint involves wearing-away of the cartilage that lines the bones. This cartilage acts as both a shock absorber between the bones, and helps to create fluid in the joint that allows the bones to glide on one another. Pain, stiffness, swelling and decreased range of motion are all symptoms associated with wearing away of the cartilage in a joint.
Several treatment techniques in the form of injections are being administered and tested to address the symptoms of OA. Cortisone injections are one such option. Cortisone is a type of “corticosteroid” – a man-made drug that is similar to cortisol, a natural hormone made by your body’s adrenal glands. The cortisone works to decrease inflammation in the joint that can cause redness, warmth, swelling, and pain. However, while cortisone can often ease the symptoms of inflammation, it does not reduce or alter the erosion of cartilage in the joint. Therefore, its effects can often be short-lived; the average benefit usually lasts 6-12 weeks. Moreover, because corticosteroids also reduce the activity of the immune system by affecting the function of white blood cells, frequent injections can actually cause damage to the cells in the knees that contribute to cartilage production.
Another alternative is “hyaluronic acid” (HA). The fluid in your joints is already composed of hyaluronic acid. However, with OA, this fluid thins and becomes less concentrated, thus providing a lesser amount of shock absorption, lubrication and protection of the joint. Some studies have found that injection of HA (also referred to as “viscosupplementation”) can provide reduction in pain symptoms and an increase in function. When compared to cortisone injections, the HA seems to take longer to have an effect, but also lasts longer (up to 1 year).
More recent research has focused on platelet rich plasma (PRP) injections. Platelets are a component of blood, and are known to assist in the repair of body tissue. PRP is produced by taking a sample of a patient’s blood and putting it through a centrifuge to increase the concentration of platelets. This is then combined with a remaining sample of blood and injected back into the knee. OrthoEvidence, an online source for evidence-based summaries of orthopaedic research, provided a synopsis of five randomized control trials and one systematic review on the efficacy of PRP treatment in knee OA. The studies reported on clinical and functional outcomes at various time points between 1 and 6 months following PRP injection. The results show some beneficial effects in reducing stiffness and pain compared to saline injections (control), but a lower effect than the use of hyaluronic acid. Overall, more studies are required with more consistent results before PRP can relied upon as an effective treatment method for OA of the knee.
Your ability to access any of these treatment options can depend on where you live and your local health care providers’ knowledge and ability to access these methods.
Sources for this article: MyOrthoEvidence.com, ACE ID #4882; myclevelandclinic.org; Can Fam Phys 2004, 50:249; Webmd.com