Nov. 14, 2006 (Washington, D.C.) -- Botox shots may do more than get rid of
wrinkles. A new study shows Botox may decrease the pain of knee osteoarthritis
(OA) and potentially prevent or forestall the need for knee replacement
The preliminary research was presented at the 2006 annual meeting of the
American College of Rheumatology.
Injecting Botox directly into the knee joint relieved pain and improved
function among people with severe knee osteoarthritis after one month, says
researcher Maren Mahowald, MD. She is the rheumatology section chief at the
Minneapolis Veteran’s Affairs Medical Center and professor of medicine at the
University of Minnesota in Minneapolis. Mahowald now plans to evaluate the
participants after three and six months.
Botox is a purified form of botulinum toxin type A and has been used to
treat wrinkles and creases on the face. It is currently FDA-approved to treat
other conditions including excessive sweating, eye disorders, and certain
neurologic conditions. Botox is being studied for treatment of headache,
ringing in the ears, overactive bladder, diabetic nerve pain, and more.
The new study comprised 37 people with moderate and severe knee
osteoarthritis. Participants received 100 units of Botox with the anesthetic
lidocaine or a dummy injection with lidocaine directly into their knee
After one month, people with severe pain showed a 28% decrease in pain and a
25% improvement in function. By contrast, people with severe knee pain who
received a placebo did not show a significant decrease in pain.
Botox injections had almost no effect among people with moderate pain, the
But it’s still early, Mahowald points out. ”Patients often have continued
decreases in pain and improvements in function after one to two months. And I
think there will be more improvements at the three-month evaluation.”
Exactly how long the effect lasts will be determined at the six-month
evaluation, she says. “People may require one to three injections per year to
control knee pain, but these injections may obviate the need for knee
The new findings came about when researchers noticed that people with limb
weakness from a stroke or polio did not develop arthritis.
They also noticed that when people with cervical dystonia -- neck muscle
stiffness and spasms -- received shots of Botox, their pain improved before
their muscle contractions stopped, suggesting that Botox may have a soothing
effect on pain nerves.