( in the bloodstream about equivalent to...)Cigarette smoking impedes tendon-to-bone healing

"So these would have been heavy smokers," Galatz says. "But another significant aspect about this study is that we did not account for other detrimental chemicals in cigarettes. Rats were not exposed to carbon monoxide, tar or the other substances that harm people who smoke. So if anything, we may have underestimated the negative effects of cigarette smoking on rotator cuff healing."

Galatz says the study also may underestimate the harmful effects of smoking because rats tend to be better healers than humans and because they were exposed to nicotine for only a few weeks following surgery, whereas people may smoke for many years before surgery, as well as continue smoking following rotator cuff repair.

"Certainly more study is necessary to definitively prove that cigarettes affect humans the same way," she admits. "But I think we have enough evidence to state that nicotine has a negative impact on healing in tendons as well as in bone."

As to how nicotine works to interfere with healing, Galatz says it's still too early to tell.

"We would have to look much more closely to learn exactly what the mechanism is, but blood supply is a potential culprit," she says. "Nicotine and cigarette smoking inhibit the formation of new blood vessels, and basically, all healing and all repair processes are aided by the formation of new blood vessels that bring in new cells. That process is assisted by increases in blood supply that may not happen as efficiently in smokers."
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Source:Washington University School of Medicine