[Joint immobilization increases reactive oxygen species: an experimental study].
OBJECTIVE
It has been shown that reactive oxygen species (ROS) contribute to the onset and progression of osteoarthritis. We investigated cartilage destruction and oxidative stress parameters in the blood and synovial fluid of knee joints of rabbits exposed to varying periods of immobilization.


METHODS
Twenty-eight mature New Zealand albino male rabbits were divided into four groups equal in number. In three groups, the knees were immobilized with a rigid cast for 3, 6 and 9 weeks, respectively. The cartilaginous tissue of the femoral condyles and tibial plateau were analyzed with respect to total count, total volume, and numerical density of chondrocytes using stereohistological methods. Antioxidant activities of superoxide dismutase (SOD), catalase (CAT), and glutathion peroxidase (GSH-Px), and oxidative stress parameters including nitric oxide (NO) and malondialdehyde (MDA) levels were measured in the plasma and synovial fluid.


RESULTS
Compared to the control group, total count and total volume of chondrocytes in the femoral condyle and tibial plateau showed significant decreases, while numerical density showed a significant increase at 3 weeks of immobilization. Subsequent immobilization periods resulted in significant decreases in all these parameters, being most remarkable compared to the control group at the end of nine weeks (p<0.001). In plasma and knee joint synovial fluid, all antioxidant enzyme activities (SOD, CAT, and GSH-Px) and oxidative stress parameters (NO and MDA) showed consistent increases compared to the control group throughout the immobilization period (p<0.001).


CONCLUSIONS
Increased levels of ROS in the blood and synovial fluid might result in cartilage destruction and ROS may be one of the potential factors involved in the etiopathogenesis of osteoarthritis. Prolonged joint immobilization should be avoided in the treatment of orthopedic diseases.
Erdem
Mehmet
M
Department of Orthopedics and Traumatology, Medicine Faculty of Gaziosmanpaşa University, Tokat, Turkey. mehmeterdem71@hotmail.com
Güneş
Taner
T
Sen
Cengiz
C
Bostan
Bora
B
Aslan
Hüseyin
H
Ozyurt
Hüseyin
H
Köseoğlu
Reşit Doğan
RD
D000818:Animals; D002374:Catalase / Q000378:metabolism; D016166:Free Radical Scavengers / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000378:metabolism; D007103:Immobilization / Q000379:methods*; D007596:Joints / Q000502:physiology*; D008297:Male; D008315:Malondialdehyde / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D011817:Rabbits; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000378:metabolism; D013582:Synovial Fluid / Q000378:metabolism
D016166:Free Radical Scavengers; D017382:Reactive Oxygen Species; D009569:Nitric Oxide; D008315:Malondialdehyde; D002374:Catalase; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase