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Arthritis Special Report

Botox and Knee Osteoarthritis

Do Botox injections offer a satisfactory non-surgical alternative for patients suffering with painful knee osteoarthritis? Trials are underway, so stay tuned …

No longer the secret potion of women and men interested in hiding facial wrinkles between the eyebrows, around the eyes, on the forehead, and around the lips, injections of Botox are now thought to be useful for more than 50 medical conditions, including excessive sweating, constipation, headache, clubfoot, and even hiccups. We may be able to add severe knee pain from osteoarthritis to the list if the results from a small preliminary study -- in which patients had a 50% or greater improvement in knee pain with Botox injections -- can be replicated.

Botox, derived from Clostridium botulinum, the bacterium that causes botulism, acts by binding to the nerve endings of muscles, blocking the release of the chemical that causes muscles to contract. When Botox is injected into a specific muscle, that muscle becomes paralyzed or weakened, but surrounding muscles are unaffected, allowing for normal function. The long-term effects of repeated Botox injections are unknown. When it comes to osteoarthritis, it’s thought that Botox injections to the knee disrupt pain nerve function and Botox may reduce nerve-related inflammation in the knee.

As you age, your knees need all they help they can get. Swivel, bend, slide, glide. Swivel, bend, slide, glide: It’s what your knees do in endless repetitions every day of your life as you go about your daily activities. No fabricated machine comes close to the capabilities of this joint. However, after years of use (and abuse), the knee eventually starts to show signs of wear and tear -- and the pain of osteoarthritis or degenerative joint disease sets in, making your 3,000 or so daily steps an extremely difficult proposition.

As you read this, 50 million Americans currently suffering from knee osteoarthritis are wincing, gulping down ibuprofen, grimacing, slathering on strong-smelling liniments, limping, and wondering how they are going to make it through another day. Each year, millions of Americans hobble into the offices of orthopedic surgeons in search of relief for their non-stop knee distress. Some will need additional prescription medication for pain relief. Many will be prescribed specific muscle-strengthening exercises to perform daily to ease the load on their delicate and damaged knees. For tens of thousands, however, the extensive damage caused by osteoarthritis will be so severe that their only remaining option is a knee arthroplasty, more commonly known as a total knee replacement.

To determine the potential benefits of injecting Botox directly into the knee joint cavity, researchers embarked on a six-month study of Botox versus placebo in 37 patients with moderate to severe refractory knee pain due to osteoarthritis. The participants (36 men and one woman) received either 100 units of Botox with lidocaine (a short-acting anesthetic) or a saline placebo with lidocaine. Double-blind assessments were scheduled for baseline, one-month, three- month, and six-month time points. Study investigators measured self-reported total pain scores and a physical function score. Scores for walking pain, day pain severity, night pain severity, and an observed timed-stands test were also factored in.

At the one-month point in this study, two placebo patients had dropped out from lack of benefit. Of the 18 patients in the severe pain group (half on Botox and half on placebo), there was a significant decrease in pain and improvement in physical function for those who received the Botox injection. Those injected with the placebo experienced minimal improvement. In the moderate pain group, neither injection produced significant changes in the primary outcome measures. Interestingly, in the moderate pain group, there was a 25% reduction in daytime pain severity after the placebo injections.

Three-month measurements were completed by January 2007, and the trial is scheduled for completion in August 2007. To date, however, thanks to Botox, researchers point to clinically and statistically significant decreases in severe osteoarthritis knee pain and improvements in physical function. "If Botox injections for refractory joint pain continues to prove beneficial, it offers a very welcome solution for fragile patients,” says Maren L. Mahowald, M.D., the Rheumatology Section Chief at the Minneapolis VA Medical Center. Dr. Mahowald, a Professor of Medicine at the University of Minnesota, Minneapolis, was principal investigator in the Botox study. "Local joint treatment with Botox injections could replace oral medications that carry the risk of systemic side effects, and Botox injections may negate or delay the need for joint surgery.” Much more research will be needed to determine the most effective and safe dose of Botox for the joint injections and the most appropriate dosing intervals.

  • For more arthritis articles, please visit the Arthritis Topic Page

    Posted in Arthritis on April 30, 2007

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