Osteoarthritis is the most common form of arthritis affecting more than 30 million Americans. It is a disease of articular hyaline cartilage which covers the ends of long bones. The purpose of hyaline cartilage is to cushion and absorb the impact of both direct stresses and shearing forces applied to the joint.
Osteoarthritis affects primarily weight-bearing joints such as the hip, knee, low back, and neck. However, it can also involve the shoulder, ankle, base of the thumb, and base of the big toe.
Despite the focus of attention in rheumatology on newer therapies for diseases such as rheumatoid arthritis, there has been relatively little done to deal with osteoarthritis. This is unfortunate since osteoarthritis (OA) is a significant cause of pain, reduced mobility, reduced productivity, and diminished quality of life.
Between symptomatic therapies consisting of rest, physical therapy, analgesics, non-steroidal anti-inflammatory drugs (NSAIDS), injections of glucocorticoids ("cortisone") and viscosupplements, there is a void until the patient requires joint replacement.
I will discuss some of the "avant-garde" therapies that are being evaluated for treatment of OA.
The first treatment is the use of stem cells. Stem cells are blank slate cells, cells that can be coaxed to differentiate into any type of tissue cell. The focus of attention has been on the use of adult mesenchymal stem cells. Studies have demonstrated that when these cells are introduced into OA joints, that they are incorporated into the articular cartilage of the affected joint. While most investigations have been demonstrated in animal models, there have been small studies and multiple anecdotal reports indicating similar results in humans.
The second type of treatment that has been studied is the use of anti-cytokine drugs. Some feel that OA is a systemic disease that requires systemic therapies.
Cytokines, which are protein messengers, play a pivotal role in the generation and propagation of inflammation. One cytokine that may have a role in the chronic inflammation seen in OA is interleukin-1. Attempts to block the effects of this cytokine have been studied with mixed results. When given systemically it didn't perform much better than placebo. When given as an injection in a joint, there have been mixed results.
Another material that has been studied is botulinum toxin (Botox). It appears to have beneficial effects in regards to pain and inflammation. It has been used in OA of the knee as well as of plantar fasciitis.
Other therapies that have been studied include platelet-rich plasma (PRP), insulin-like growth factor, and bone morphogenic protein. Results are controversial.
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