Effect of Running on Inclined Treadmill on the Occurrence of Knee Joint Osteoarthritis in the Male and Female Wistar Rats

Abstract

Background: Runners and team players frequently use motorized treadmill to impose exercise stress. On the other hand, some studies showed that running may lead to knee osteoarthritis (OA). The current study aimed at comparing the effects of running on inclined treadmill on the occurrence of knee joint OA between male and female rats with the same age and body weight. Methods: Forty adult male and female Wistar rats were randomly and equally divided into two male and female control and two male and female runner groups. A similar running exercise was performed in both male and female rats for six weeks on a treadmill with 18°inclination. On the day 43, animals were euthanized and the whole rat knee joints were evaluated microscopically and macroscopically. Results: The gross evaluation of knee articular surface in four male and all female runner rats were irregular. Mankin's findings were higher in the female runners than the male runners. In female runners, the synovial layer showed a mild sinovitis. The average of cartilage thickness and chondrocyte number were significantly lower in female runner group than the female controls. Conclusions:The obtained results showed no sinovitis and moderate sinovitis in male and female runners, respectively. There was mild OA both in male and female runners. The current study confirmed that the development of knee OA may be related to the gender differences.