CHAPEL HILL - A new class of non-aspirin pain medicine now widely prescribed for arthritis symptoms may impair ligament healing associated with sprains, according to laboratory findings at the University of North Carolina at Chapel Hill.
The newer medications, cyclooxygenase-2 specific inhibitors, or COX-2 inhibitors, are the latest nonsteroidal anti-inflammatory drugs. COX-2 inhibitors are marketed as having the same effectiveness against pain and swelling of inflammation as the older NSAIDs but without the increased risk of gastrointestinal side effects, including stomach ulcers, which have been linked to NSAID use. The newer drugs are sold in the United States under the brand names Celebrex and Vioxx.
A report of the new findings appears in the November 14 issue of the American Journal of Sports Medicine.
Dr. Lawrence E. Dahners, professor of orthopedics at UNC-CH School of Medicine, said he and his UNC co-authors, Drs. Christopher L. Elder and Paul S. Weinhold, were not aware of any research highlighting the effects of COX-2 inhibitors on soft tissue injuries such as sprains. They noted that among the widest uses of nonsteroidal anti-inflammatory drugs is in the treatment of such injuries.
"And so the question came up whether it was good to prescribe COX-2 inhibitors for patients who were getting sprains," Dahners said. The Carolina orthopedist noted that previous studies in the 1980s had shown that anti-inflammatory drugs were bad for bone healing and shouldn't be given to patients with fractures. "We then did a study to examine the effects of nonsteroidals [NSAIDS] on ligament healing. To our surprise, we found they made ligaments heal better. Therefore, they were very good medications for people with sprains, sprains being ligament injuries," Dahners said. Thus, with the advent of COX-2 inhibitors, and given a dearth of research on their role in ligament healing, Dahners and his colleagues decided to investigate this issue. The study in rats involved an experimental model for an acute injury of the medial collateral ligament. In humans, the MCL runs up the inside of the knee and is the most common site of knee sprains. Postoperatively, half the animals were given the COX-2 inhibitor celecoxib for the first six days of recovery, the other half were not. About two weeks later, the injured and uninjured ligaments were tested for healing strength. Celecoxib decreased ligament healing strength by 32 percent. Dahners points out that some of the older NSAIDS block two enzymes associated with pain and inflammation: cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2). In previous studies, he found that these medications actually increased the strength of ligament healing by roughly 40 percent.
"This would indicate that if you had a soft tissue injury -- hurt your back, sprained your ankle --you probably should try to take the older anti-inflammatory drugs rather than the new ones, unless your stomach is sensitive to those medications," Dahners advised.
Still, he cautioned that the findings remain preliminary. The long-term outcome of COX-2 inhibitors on ligament healing needs further study, as does further clarification of the roles of the enzymes COX-1 and -2 on soft tissue related to muscle and bone.