Histomorphometrical Changes on the Knee Joints of Male and Female Rats After Moderate Exercise Program

Introduction: Osteoarthritis (OA) is one of the most common joint diseases that is accompanied with cartilage loss and finally leads to joint destruction. The most common joint that is affected in OA is the knee joint. Knee joint OA may lead to significant illness.  Methods: The effect of excessive running load on the development of knee OA was investigated in rats. This study aimed to evaluate the same moderate running program on the knee cartilage thickness and its lesions in Wistar rats (both sexes with the same age and body weight). Thirty two male and female Wistar rats with no significant difference in their body weight were randomly divided into four equal groups with the same conditions. Eight of each sex was selected as control groups while running exercises were performed in remained 16 male and female rats for 6 weeks on a motor-driven treadmill for 60 minutes each day, 5 days per week. On day 43, all animals were killed and their knee joints were prepared for histomorphometrical study. The histopathological measures, including cartilage lesion thickness, cartilage thickness, maximum degeneration width, minimum degeneration width, degeneration height, cartilage lesion thickness to cartilage thickness ratio and also area of the degenerative parts were evaluated.  Results: The severity of OA lesions was graded on a scale adopted from OARSI (Osteoarthritis Research Society International) histopathology instructions. Cartilage lesion thickness and degenerative area of the lesions in the female exercise group were significantly more than those in the male exercise group. Other assessment parameters in the female running exercise group differed from those in male exercise group, too (P>0.05).  Conclusion: Histopathological findings revealed mild and moderate OA in the male and female running rats, respectively.