The Study Of The Relevance Between Subchondral Bone And Endplate Cartilage In The Process Of The Rabbit Intervertebral Disc Degeneration

【Objectives】To research the relevance between subchondral bone and endplate cartilage in the process of endplate cartilage degeneration by establishing the animal models of rabbit intervertebral disc degeneration, in order to discuss the causes and pathogenesis of endplate cartilage degeneration.【Methods】30 clean New Zealand white rabbits of 6-8 months were randomly divided into experimental and control groups,each 15.The experimental group was ablated the rabbit thoracic 10-lumbar vertebrae 4 spinous process and part of the facet joints and excisioned supraspinous and caused ligament to establish the thoracolumbar degenerative disc model,the control group did not damage the spinal stability.In the 12,16,20 weeks after operation,all animal model's spines was photographed by X-ray,and endplate cartilage and bone carried out the HE staining of pathological observation,and scanning electron microscope observed the ultrastructural changes of endplate cartilage and subchondral bone,as well as observed the subchondral bone of matrix metalloproteinase-1(MMP-1)and insulin-like growth factor-1(IGF-1) immunohistochemistry expression.【Result】X-ray showed that with the time extended the intervertebral discs gradually degenerated,endplate cartilage calcified and thinningz and subchondral bone sclerosis and density increased.HE staining demonstrated with time extended endplate cartilage and subchondral bone cells decreased, collagen damaged.Scanning electron microscopy showed that the experimental group endplate cartilage degenerated,typeⅡcollagen damageed,proteoglycan seriously lost,and subchondral bone destruction and bone remodeling coexist, and a large number of trabecular bones were disorders,typeⅠcollagen fibers of bone matrix appeared fissures,and at the same time parts of emerged reorganization to form a more compact structure.All were more obviously with the time extended and was direct correlation with the degree of disc degeneration.And degeneration of the experimental group was more obviously than the control group.Immunohistochemical staining,MMP-1 and IGF-1 in the subchondral bone of the experimental group expressed more than the control group.With the extension of observational time,staining intensity gradually increased both.Statistics between the experimental group and the control group were significance,the comparison among the teams also had statistical significance(P＜0.05).【Conclusion】The endplate cartilage degeneration and intervertebral disc degeneration was found closely relation by using the successful operation that damaged the spinal stability to induce the endplate cartilage degeneration in animal models.Subchondral bone in the process of endplate cartilage degeneration constantly expressed MMP-1 and IGF-1 and it's structural damage caused sclerosis and reconstruction,which made the endplate cartilage on the structure and function of a destructive effect. This suggested that the endplate cartilage degeneration and the subchondral bone sclerosis had the closely relationship in the process of disc degeneration.The sclerosis of subchondral bone promoted the endplate cartilage degeneration.