ABSTRACT
Objective To develop a shear force-induced intervertebral disc degeneration (IDD) in vivo animal model, and investigate the relationship between shear stress and IDD. Methods A total of 20 Japanese white rabbits were randomly divided into two groups. In loading group (n=10), shear force of 50 N was applied on the disc of L4/5 for 4 weeks by a custom-made external shear force loading device. In control group (n=10), the animals underwent a sham operation with the external loading device situated, but their discs remained unloaded. After 4 weeks, all the intervertebral discs of L4/5 were executed for the pathologic examination. Results The postoperative radiographic examination showed a perfect position of the loading device, and the operation process and implanted loading device had no effect on daily activities and diet of the experiment animals. The pathological examination showed an irregular arrangement of annulus fibrosus and a significant decrease of normal nucleus pulposus cells in loading group. Conclusions The new custom made device greatly reduced the wounds on animal vertebra and provided a reliable shear force. The development of in vivo animal model indicates that IDD can be induced by shear force, which is of significance to further study the relationship between loading and IDD.