抄録
Epidemiological studies have suggested that because of their frequent exposure to mechanical vibration, bus and truck drivers are especially susceptible to disc disorders. It has been reported that drivers of such vehicles are subjected to low-frequency vibration up to 6 Hz. The intervertebral disc regulates the viscoelastic properties of spinal segments. The intradiscal pressure will play an important role in the mechanical response of a spinal segment to vibrations. While previous studies have made direct in vivo measurements of intradiscal pressure under static conditions, no data has been reported on intradiscal pressure response to vibration loading under either in vivo or ex vivo conditions. The present study is to measure the intradiscal pressure response to cyclic loading in a physiological saline solution simulating in vivo conditions. The effect of mean load, amplitude and frequency of cyclic loading on the intradiscal pressure response was examined using calf lumbar spinal segments. The experiment employed mean loads of 20, 60, and 100 N with amplitudes of 10, 15, and 20 N and compared the low-frequency effects of 0.05, 0.5 and 5 Hz. The mean load was applied for one hour before the cyclic loading test, in order to consider the equilibrium intradiscal pressure. Therefore, it was confirmed that the relationships of load versus displacement, and load versus intradiscal pressure were affected by the mean load and the frequency of cyclic loading.
