Oct. 20, 2008 -- Roughly 300,000 knee replacement surgeries are performed each year in the U.S., and while most patients do well, some have lingering pain even when the operation is successful.
But a strategy developed at Chicago's Rush Medical Center appears to significantly reduce chronic pain following knee surgery.
Rush researchers report that patients treated with the fibromyalgia drug Lyrica immediately before surgery and for two weeks afterward had significantly less chronic pain six months later, compared with patients who were not treated with the drug.
Anesthesiologist and study lead author Asokumar Buvanendran, MD, tells WebMD that it is increasingly clear that drugs given at the time of surgery can have a long-term effect on pain.
"We showed that treating patients immediately before and after surgery was associated with long-term improvements in pain control and quality of life," he says.
Chronic Pain After Surgery
Buvanendran says it is not uncommon for patients to develop chronic pain after surgery, but the condition is poorly understood and underdiagnosed.
Studies suggest that between 1% and 10% of patients who have knee replacement surgery have lingering, long-term pain that is not associated with the arthritis or other conditions that lead to surgery.
Known as chronic neuropathic (nerve-related) pain, the condition has been difficult to treat precisely because there is no widely agreed upon physiological cause.
"Many physicians don't even recognize it and that is why patients often end up going from doctor to doctor to get help," he says.
In June 2007, Pfizer's epilepsy drug Lyrica became the first approved treatment for the chronic pain condition fibromyalgia. It is also approved for the treatment of chronic pain caused by diabetic nerve damage.
According to Pfizer, the drug works by targeting the pain-causing electrical signals in damaged nerves.
With this in mind, the Rush researchers got the idea to treat patients with the drug around the time of surgery in an effort to prevent chronic nerve-related pain later on.
Buvanendran reported the results of the first randomized trial of the strategy Sunday at the 2008 Annual Meeting of the American Society of Anesthesiologists in Orlando, Fla. The study was funded in part by Pfizer.
Lyrica vs. Placebo
The study involved 240 patients undergoing knee replacement surgery who were divided into two groups.
Half the patients were treated with 300 milligrams of Lyrica two hours before surgery and 150 milligrams of the drug twice a day for two weeks following surgery. The rest of the patients received placebo treatments given at the same time intervals.
Neither the patients nor the doctors and nurses administering the drugs knew which treatment the patients were getting. All the study participants also received standard pain medication following surgery.
Six months after surgery, there were no complaints of chronic neuropathic pain among patients treated with the fibromyalgia drug, while 5.3% of placebo-treated patients continued to have pain.
The Lyrica-treated patients also had a greater range of motion in surgically treated knees following surgery.
Buvanendran says the drug is now routinely given to patients undergoing knee replacement surgery at Rush University Medical Center.
Rush surgeon Aaron G. Rosenberg, MD, tells WebMD that the study is not the first to show that drugs given to patients around the time of surgery can improve long-term outcomes.
Rosenberg was not involved with the latest trial, but he did participate in a 2003 study which showed improved long-term outcomes among knee replacement patients treated with a Cox-2-type pain reliever immediately before and after surgery.
"We showed that patients treated for a couple of weeks with a relatively cheap anti-inflammatory had better range of motion a month after surgery," he says. "That is important because the quicker knee surgery patients get moving the better."