Although Botox is most commonly associated as being a cosmetic treatment used to diminish the appearance of facial wrinkles, it has been FDA approved as a treatment for a number of other health problems, including eye disorders and certain neurological conditions. In addition to being studied as a treatment for diabetic nerve pain, headaches and overactive bladder, researchers are currently looking at Botox as a treatment for reducing severe pain related to osteoarthritis of the knee.
How Botox Works
Botox is injected directly into the knee joint to relieve pain. The same bacterium that causes botulism weakens or paralyzes the muscle at the injection site, although it has no effect on the adjacent muscles, which continue to maintain strength and normal physical function. Botulinum toxin binds to the motor nerve endings of muscles, blocking the release of acetylcholine, the chemical that causes muscles to contract.
For patients suffering osteoarthritis of the knee, Botox injections to the knee work by targeting pain nerves within the knee joint. The injections may also reduce nerve-related inflammation of the muscles surrounding the knee. Rheumatologists at the Mayo Clinic point out that while it is still unclear how effective this treatment might be, a growing body of research indicates encouraging results.
Doctors use a special ultrasound device to guide a small needle that injects Botox into the arthritic knee joint cavity, which is filled with synovial fluid. Botulinum toxin can be administered without anesthesia; therefore, a person may feel some minor discomfort as the Botox is injected. Treatment takes only a few minutes, but it may improve the quality of life for people who suffer severe pain of arthritis in the knees. One drawback is that the injections are expensive and are not covered by most health insurance plans. While the cost of Botox treatments can vary depending on factors such as the clinic location, qualifications of the physician and number of injections given, as of August 25, 2009, a vial of Botox cost more than $1,000.
According to researchers at the University of Minnesota at Minneapolis, Botox injections as a local pain treatment for osteoarthritis affecting the knee could eventually replace oral medications, which have been known to cause serious systemic side effects in some people. Marlen L. Mahowald, M.D., a professor of medicine at the University of Minnesota at Minneapolis and lead investigator in the study is optimistic that Botox treatment could even delay the need for knee surgery in certain patients. After just three months, participants in the 2007 clinical trial reported significantly less pain, improved range of motion and better knee function following Botox treatment.
In the past, some patients reported muscle weakness when injected with Botox to treat cervical dystonia, a condition in which a person suffers muscle stiffness and spasms of the neck. However, none of these same side effects were reported when Botox was used as a treatment to alleviate the pain and inflammation associated with arthritis. Mahowald, who is also the Rheumatology section chief at the Minneapolis VA Medical Center, points out that one reason why no adverse reactions have been reported might be that such a small dose is used.
Despite the positive benefits of Botox treatments for refractory joint pain, more research is needed to determine the efficacy and safety of the drug when injected into painful joints. Yet the results of earlier preliminary studies presented at the 2006 American College of Rheumatology Annual Scientific Meeting in Washington, D.C., identify the potential of Botox injections as a method of pain relief for those who suffer chronic knee joint pain. Botox may be another viable option for the treatment of arthritis, especially for those who are not candidates for total knee replacement surgery.