Mechanical Response of Intervertebral Disc Under Cyclic Compression

The intervertebral disc (IVD) was vulnerable to injury or early degenerative lesions. Although much research has been addressed to investigate the mechanical properties of discs, such as compression, tension and bending, there was little research on the mechanical behavior of IVD under cyclic compression. The purpose of this study was to investigate the mechanical response of discs under physiological loads, and to study the effects of pressure peak and rate on the mechanical behavior of IVDs. The results showed that loading displacement of sheep lumbar discs decreases with the increase of the number of cycles and there is the both stage of transient reduction and asymptotic stability, but the unloading displacement only slowly decreased. The height of the discs decreases continuously under load. Loading and unloading displacements of discs increase with the increase of pressure peak, but decrease with the increase of pressure rate. Compressive stiffness increases with the increase of pressure peak or rate.