EFFECT OF MECHANICAL STIMULI ON REMODELING AND MINERAL DENSITY OF THE SPINE

Abstract

The aim: The aim of our study was to determine effect of whole body vibration on the bone tissue remodeling, determine the correlation between bone mineral density, markers of bone metabolism and level of vibration stimulus. Materials and methods: Four experimental groups Wistar rats were exposed to vertical whole body vibration during 28 days. Blood intake and QCT-scanning of the lumbar spine was performed on the 28th and 56th day of study. Results: The largest loss of trabecular bone was observed in experimental groups III (0.51g) and IV (1.15g), which was decreasing to 12% (p<0.05) and 14% (p<0.05), respectively, in comparison with the control group. After 56th day of the experiment, bone loss dynamics was the following: in the 1st group ≤ 10% (p <0.05), in the 2nd ≤ 12% (p <0.05), in the 3rd ≤ 17 % (p <0.05), and 4th ≤ 22% (p <0.05) compared with the control group. Changes in the level of hydroxyproline in the first experimental group were not statistically significant (p>0.05), in the second group – increased by 19.3% compared with the control rates, in the third – by 65.3%, and in the fourth – the level doubled (p<0.05). Increase of free hydroxyproline indicates violations in the balance between destruction and compensatory acceleration of collagen biosynthesis, which gradually decreases up to the 56th day. It has been determined that with the increase in vibration frequency, elevation of osteocalcin level in rats’ blood is observed. Conclusions: Acceleration 0.51g increases the rate of bone metabolism, causes collagen metabolism disorders, loss of bone mineral mass, which further leads to osteoporosis.