Nicotine Slows Healing of Rat Shoulder Tendons
Finding has implications for rotator cuff injury repair in humans
MONDAY, Sept. 11 (HealthDay News) -- Exposure to nicotine can delay healing in rats that have undergone shoulder tendon surgery, which may have implications for humans undergoing rotator cuff injury repair, researchers report in the September issue of the Journal of Bone and Joint Surgery.
Leesa M. Galatz, M.D., of the Washington University School of Medicine in St. Louis, and colleagues compared tendon-to-bone healing in 72 rats with transected shoulder tendons reattached to the humeral head, then exposed to nicotine or saline solution for 10, 28 or 56 days.
The researchers found longer-lasting inflammation in rats administered nicotine than in those administered saline. Early cell proliferation was speedier in rats on saline than on nicotine, as was expression of type-1 collagen after 28 days.
Mechanical function improved in both groups, but maximum stress after 10 days was lower in rats on nicotine than on saline. At 28 days, maximum force was significantly lower in the nicotine group, but it was significantly higher than the saline group after 56 days, the researchers report.
"Nicotine caused a delay in tendon-to-bone healing in a rat rotator cuff animal model," the authors write. "Mechanical properties increased over time in both groups, but the properties in the nicotine group lagged behind those in the saline solution group."