title: The effects of joint immobilization on articular cartilage of the knee in previously exercised rats.
abstract: Studies have determined the effects of joint immobilization on the articular cartilage of sedentary animals, but we are not aware of any studies reporting the effects of joint immobilization in previously trained animals. The objective of the present study was to determine whether exercise could prevent degeneration of the articular cartilage that accompanies joint immobilization. We used light microscopy to study the thickness, cell density, nuclear size, and collagen density of articular cartilage of the femoral condyle of Wistar rats subjected to aerobic physical activity on an adapted treadmill five times per week. Four groups of Wistar rats were used: a control group (C), an immobilized group (I), an exercised group (E), and an exercised and then immobilized group (EI). The right knee joints from rats in groups I and EI were immobilized at 90 °C of flexion using a plastic cast for 8 weeks. Cartilage thickness decreased significantly in group I (mean, 120.14 ± 15.6 μm, P < 0.05), but not in group EI (mean, 174 ± 2.25), and increased significantly in group E (mean, 289.49 ± 9.15) compared with group C (mean, 239.20 ± 6.25). The same results were obtained for cell density, nuclear size, and collagen density (in all cases, P < 0.05). We concluded that exercise can prevent degenerative changes in femoral articular cartilage caused by immobilization of the knee joint.
authors.affiliation: Department of Morphology and Genetics, Federal University of São Paulo, São Paulo, Brazil.
authors.forename: Diogo Correa
authors.initials: DC
authors.lastname: Maldonado
authors.forename: Marcelo Cavenaghi Pereira da
authors.initials: MC
authors.lastname: Silva
authors.forename: Semaan El-Razi
authors.initials: Sel-R
authors.lastname: Neto
authors.forename: Mônica Rodrigues
authors.initials: MR
authors.lastname: de Souza
authors.forename: Romeu Rodrigues
authors.initials: RR
authors.lastname: de Souza
mesh_terms: D000818:Animals; D001284:Atrophy / Q000517:prevention & control; D002358:Cartilage, Articular / Q000473:pathology / Q000502:physiology*; D003094:Collagen / Q000032:analysis; D007103:Immobilization / Q000009:adverse effects*; D007592:Joint Diseases / Q000503:physiopathology / Q000517:prevention & control; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D010805:Physical Conditioning, Animal; D051381:Rats; D017208:Rats, Wistar
chemical_list: D003094:Collagen