Cigarette smoking impairs ligament healing, researchers find

The list of reasons you shouldn’t smoke has gotten longer. Researchers at Washington University School of Medicine in St. Louis are reporting that smoking interferes with ligament healing.

Rick Wright

“Our studies also have shown a decreased macrophage response that may help explain why we see this delayed or decreased healing response,” Wright says.

Between 20 and 25 percent of the U.S. population smokes. Wright and Sandell say that although the prevalence of smoking among athletes is slightly lower, a significant percentage of recreational and even professional athletes continue to smoke. Many others use chewing tobacco, which may cause some of the same effects. But that’s not yet clear since the mice in this study were exposed to smoke rather than to nicotine only.

“There are two ways to do smoking studies in animal models,” Sandell explains. “One looks only at a single component, like nicotine. The other way is to use a method like the one we employed that includes all of the toxins found in smoke. We think exposing the mice to cigarette smoke itself is most relevant because when people smoke, they don’t get individual components. They get everything.”

Sandell and Wright say their findings point to yet another reason smokers would do well to quit.

“Many patients don’t want to hear it, but these results suggest that smoking affects anyone who needs ligament-repair surgery.” Wright says. “I counsel surgery patients to at least try to decrease smoking because, if nothing else, that will improve the healing of their surgical incisions. Quitting smoking is good health management regardless, but in patients having this kind of surgery, there are extra advantages.”

Wright and Sandell are conducting more studies. Currently they are comparing mice exposed to smoke before MCL surgery to those exposed both before and after surgery to see whether ending smoking might assist ligament healing.

“Because ligament injuries usually occur suddenly, it’s unlikely people will stop smoking until after their injury,” Sandell says. “So we want to learn whether smoking cessation near the time of surgery might help reverse the healing delays we saw in this study.”

Gill CS, Sandell LJ, El-Zawawy HB, Wright RW. Effects of cigarette smoking on early medial collateral ligament healing in a mouse model. Journal of Orthopaedic Research, vol. 24, pp. 2141-2149. Dec. 2006.

This research was supported by grants from the National Institutes of Health and by the National Football League Charities.

Washington University School of Medicine’s full-time and volunteer faculty physicians also are the medical staff of Barnes-Jewish and St. Louis Children’s hospitals. The School of Medicine is one of the leading medical research, teaching and patient care institutions in the nation, currently ranked fourth in the nation by U.S. News & World Report. Through its affiliations with Barnes-Jewish and St. Louis Children’s hospitals, the School of Medicine is linked to BJC HealthCare.