Researchers at Washington University School of Medicine in St. Louis are reporting that smoking interferes with ligament healing.
The medial collateral ligament (MCL), a ligament that supports the knee joint. Each year in the United States there are more than 20 million reported ligament injuries, and MCL injuries are the most common. They also are the most common injuries seen in competitive and recreational sports.
It’s not clear exactly how many MCL injuries occur annually because many go unreported. “A lot of MCL injuries never make it to an emergency room because patients will have a sore knee but don’t seek treatment,” says Rick W. Wright, M.D., associate professor of orthopaedic surgery and a senior investigator on the MCL study.
The researchers say athletes who smoke should keep these findings in mind before driving for a lay-up, sliding into second base or lacing up a pair of ice skates. The soft tissue healing that occurs following ligament injuries occurs in stages.
There is an immediate pooling of blood near the injury, the sort of hemorrhaging that will cause swelling right away. This initial response is followed by several days of inflammation, in which cells called macrophages flock to the injury site and secrete substances called cytokines and chemokines. Those, in turn, recruit more cells to assist in healing. That process of cellular proliferation and synthesis lasts for several days to several weeks. The final stage of healing involves remodeling of the tissue and can continue for months and even years.
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.
