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Objective:Illuminate the injury to knee articular cartilage of rabbits under different stress and the distribution of cartilage cells which be dameged; study in biological response of living rabbits under different types of articular cartilage stress and the effect of maintenance in the biomechanical properties of cartilage by stress stimulationMethods:Experiment I:In vitro experiments, test the connection between effect of different stress load and distribution of deformation of articular cartilage, selected rabbits by random, taked the whole paragraph intact femur on both sides of the knee anatomy to remove soft tissue, exposed the full knee cartilage of distal femur and protectd the cartilage in PBS solution, prepared femur with denture powder, which maked it easy to fixed. Prepared testing machine, femur were placed on testing machine to keep the pressure plane straight against the cartilage, load specimens in each group in turn. Set load parameter to 15,30,50Mpa/s,0.3Hz, a total of 2min. computer recorded the head pressure displacement and pressure automatically. After loading, taked full-thickness cartilage, in accordance with rules of indentation, cut cartilage into the square, and put it into high glucose DMEM solution which changed daily.3 days later, pressured tissues was dyed with the FDA/Hoechst,observed the survival ratio, mortality ratio of chondrocyte and distribution of dead cells.Experiment II:in vivo rabbit knee in vivo contact stress under different load change experiment. Rabbits were randomly divided into experimental group distraction decompression, weight-bearing pressure test group and control group. The control group received no treatment; drawing decompression experimental group 25% respectively from the body weight of rabbits decompression and 50% of the load weight load autologous decompression,30°angle between the drawing stress to do pendulum movement 60 times/min,20min/time,2 times a day, each time after decompression traction lift. Weight-bearing pressure in rabbits in experimental group were given 25% of the body weight from knee and 50% vertical compression loads from the vertical compression load of the body weight of knee,20min/time,2 times a day, lift the weight after each compression. Animals in each group, respectively, decompression or load test line 2,4 and 6 weeks after the death of two animals, anatomical knee joint, taking full-thickness cartilage of distal femur, and the HE staining to observe the morphology of chondrocytes in each group Changes and the distribution of damaged cells.Results:Experiment I:Load were significantly higher than mortality in control group mortality rate (5.64+0.72%), fewer dead cells in control group, the basic distribution of the cartilage surface. Loaded group, as shown above, with the loading pressure, cell mortality was higher, and the microscope, Dead cells are widely distributed in the cartilage layers.Experiment II:in vivo rabbit knee,test the change of the knee articular cartilage of living rabbits under different stress. Rabbits were divided into different experimental group randomly,such as stretch and decompression group, weight-bearing pressure test group and blank group. The blank group received no treatment; in stretch and decompression test group,25% from the body weight of rabbits decompression and 50% of the load weight load autologous decompression respectively to do pendulum movement at 30 angle 60 times/min,20min/time, twice a day, each time after decompression traction lift. Weight-bearing pressure in rabbits in experimental group were given 25% of the body weight from knee and 50% vertical compression loads from the vertical compression load of the body weight of knee,20min/time,2 times a day, lift the weight after each compression. Animals in each group, respectively, decompression or load test line 2,4 and 6 weeks after the death of two animals, anatomical knee joint, taking full-thickness cartilage of distal femur, and the HE staining to observe the morphology of chondrocytes in each group Changes and the distribution of damaged cells.Conclusion:1. FDA/Hoechst dying method can distinguish between living cells and dead cells well.2. As the stress increased, the more cartilage damaged, the higher the rate of died cell was obtained.3. As the intra-articular pressure increased, the more cartilage damaged, the more died cell get.
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