Anti-inflammatory drugs commonly used to relieve pain after shoulder surgery may impair healing, new animal research suggests.

Rats that were treated with anti-inflammatory drugs had poorer healing than animals that were not given the drugs, researchers reported Friday at a meeting of the American Orthopaedic Society for Sports Medicine in Quebec City, Canada.

The findings “should give us pause” about the use of anti-inflammatory drugs in people who have rotator cuff surgery, study investigator Dr. Scott A. Rodeo of the Hospital for Special Surgery in New York told Reuters Health in an interview.

But Rodeo cautioned that more research is needed to confirm the results.

“At this point, we can’t make recommendations” about the use of anti-inflammatory drugs after rotator cuff surgery,

If the findings are confirmed, Rodeo said it may be wise to avoid giving the drugs to patients who are likely to have problems healing after shoulder surgery, including the elderly, people with the brittle-bone disease osteoporosis and people who are having repeat surgery.

Rodeo and his colleagues tested the effect on healing of drugs called nonsteroidal anti-inflammatory drugs, or NSAIDs. This class of drugs includes over-the-counter pain relievers such as ibuprofen, aspirin and naproxen, as well as the newer prescription drugs celecoxib (Celebrex) and rofecoxib (Vioxx).

NSAIDs are often used to relieve pain after surgery to repair the rotator cuff, which is made up of the muscles and tendons that hold the upper arm bone to the shoulder.

Previous research has shown that NSAIDs have a negative effect on bone formation, Rodeo said. Because healing after rotator cuff surgery involves bone formation - bone grows into the outer tendon - Rodeo and his colleagues set out to see whether NSAIDs affect healing after the shoulder surgery.

Anti-inflammatory drugs “really did have an adverse effect in this model,” Rodeo said.

Rodeo’s team found that rats treated with the NSAIDs celecoxib or indomethacin after surgery experienced poorer healing than animals that did not receive any anti-inflammatory medication.

Among the 120 rats treated with one of the drugs, five tendons failed to heal at all. None of the tendons in rats that did not receive the drugs failed to heal.

This is the first study to suggest that anti-inflammatory medications impair healing after rotator cuff surgery, Rodeo said.

But the New York researcher cautioned that the findings need to be confirmed in a study involving larger animals, such as sheep, as well as in human trials before changes are made in clinical practice.

Still, Rodeo cautioned, “there is the potential for adverse effects.”

If future studies bear out the findings, Rodeo said that there are other options for relieving pain after shoulder surgery, including narcotic pain medications. Unfortunately, narcotics can be addictive and may cause side effects, including constipation and nausea, Rodeo said.