[Changes of biomechanical properties in goats at different times after ovariectomy]

This paper presents the changes of biomechanical properties in goats at different times after ovariectomy. 14 goats were randomly divided into three groups. These goats were ovariectomized and sacrificed at 180 days (n = 4), 360 days (n = 5) and 540 days (n = 5) after the operation. The right femur, tibia and metatarsus were taken out. The structure mechanical properties of femora were measured with the three-point bending method and those of metatarsus were measured with the compressing method. The material mechanical properties of flexure, compress and tensile strength in the compact bone specimens of femora and tibiae taken from broken ends were also measured. The results showed that the one-year group, compared with the half-year group, had all the bone geometric parameters decreased, but not statistically significant (P > 0.05); the elastic modulus of three-point bending of femora decreased by 23.27% and the others had no significant difference (P > 0.05); all the material parameters of flexurel, compress and tensile strength in compact bone specimens decreased, but only the ultimate strength of tibiae of flexure, compress and tensile strength decreased obviously (P < 0.05). The one and a half year group, compared with the one year group, had the bone density of femora and tibiae decreased, but not statistically significant (P > 0.05). All the bone geometric parameters of tibiae and the thickness of bone of femora increased (P < 0.05). The break load of three-point bending of femora increased (P < 0.05). Probably, it was related to the increase of the body weight in the one and a half year group. The elastic modulus and the ultimate strength decreased, but not statistically significant (P > 0.05). When compact bone specimens were used, the ultimate strength and elastic modulus of femora and tibiae in compress and the elastic module of tibiae in flexure decreased obviously (P < 0.05); and the others had no significant changes (P > 0.05). This study indicated that the degree of osteoporosis in ovariectomized goats increased at half a year, one year, and one and a half year postoperation, and hence suggested that the ovariectomized goat be a pretty useful big animal model of osteoporosis.