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BACKGROUND: Exercise is an effective method for preventing and treating osteoporosis, but it is unclear whether its effect on postmenopausal osteoporosis is related to changes in bone autophagy levels. OBJECTIVE: To observe the effects of exercise via cellular autophagy on the morphology and mechanical properties of bone tissue in ovariectomized rats, and to explore the mechanism of exercise on bone mass in ovariectomized rats from the perspective of autophagy. METHODS: A rat model of postmenopausal osteoporosis was established, and a 24-week moderate-intensity exercise was used for intervention. After the experiment, serum estradiol levels were measured by ELISA, and bone mineral density and bone microstructure of the cortical and trabecular bone were detected by micro-CT. The biomechanical indicators of the tibia were tested by a three-point bending test. Autophagosomes were observed by transmission electron microscopy. The expression of LC3 and ATG7 proteins was analyzed by western blot. RESULTS AND CONCLUSION: The serum estradiol level in the ovariectomized group was significantly lower than that of the sham-operation group and ovariectomized+exercise group (P < 0.01). The body mass of rats in each group increased, and the order was the ovariectomized group > the ovariectomized+exercise group > the sham-operation group > the sham-operation+exercise group. The bone mineral density and bone mass of rats in all groups significantly increased (P < 0.01), but the increase in the ovariectomized group was significantly lower than that of the other groups, and the increase in the ovariectomized+exercise group was significantly higher than that of the ovariectomized group. Compared with the sham-operation group, the bone mineral density of the tibial cancellous bone in the sham-operation+exercise group was significantly increased (P < 0.01), while the bone mineral density in the ovariectomized and ovariectomized+exercise groups was significantly decreased (P < 0.01). Compared with the ovariectomized+exercise group, the ovariectomized group showed significantly lower bone volume fraction, number of trabeculae, and bone mineral density of cancellous bone (P < 0.05), extremely significantly lower trabecular thickness (P < 0.01), and significantly higher mean trabecular pattern factor, trabecular separation, and structural model index (P < 0.01). Compared with the ovariectomized group, the LC3-II/LC3-I ratio and the relative expression of ATG7 protein significantly increased in the ovariectomized+exercise group (P < 0.05). Compared with the sham-operation and ovariectomized groups, the number of autophagosomes increased in the sham-operation+exercise and ovariectomized+exercise groups, respectively. To conclude, moderate-intensity treadmill exercise can improve the bone microstructure and biomechanical properties of the tibial cancellous bone and increase bone mass in ovariectomized rats by increasing serum estradiol levels and bone autophagy levels. [ABSTRACT FROM AUTHOR]

BACKGROUND: The main reason for the failure after total hip arthroplasty is aseptic loosening of the prosthesis. The traditional acetabular cup fixation method is still controversial in maintaining the initial stability of the acetabular cup. It is a new method that can be considered to further improve the fixation method of the acetabular cup to increase its stability. OBJECTIVE: To analyze the feasibility and superiority of locking screw assisted acetabular cup fixation. METHODS: The digital model of acetabular cup and screws were reconstructed and assembled by software Solidworks. The Von-Mises and shear stress of the acetabular cup and screw by three methods, including acetabular cup, acetabular cup with ordinary cancellous bone screw, and acetabular cup with locked cancellous bone screw, were compared. RESULTS AND CONCLUSION: (1) The finite element model of the established acetabular cup and screw had excellent geometric similarity and could be used for finite element analysis. (2) The acetabular cups with locking screws received less Von-Mises and shear stress than other methods. (3) The locking screws could bear higher stress than ordinary screws and effectively dispersed the shear stress of acetabular cups. (4) It is concluded that the combination of locking screws to fix the acetabular cup can effectively prevent the instability of the acetabular cup and the loosening of the prosthesis; it can better provide stability for the acetabular cup and the mechanical environment that the bone tissue grow in the later stage. The acetabular cups with locking screws have obvious advantages than other ordinary screw, which has the limited bearing capacity and low anti-acetabular cup shear force. [ABSTRACT FROM AUTHOR]