Histological observation of intervertebral disk degeneration caused by bilateral zygapophysial joints destruction / 中国矫形外科杂志

ABSTRACT

[Objective]To study whether intervertebral disk degeneration can be induced by destroying bilateral zygapophysial joints of New-Zealand rabbit.[Method]Thirty male New-Zealand rabbits were randomly divided into operation group on the bone and operation group on the soft tissue.In operation group on the bone,L4 and L5 inferior articular processes were en bloc excised,L5 and L6 superior articular processes were retained.In the operation group on the soft-tissue,Only L3 to L7 paravertebral muscles were stripped.In operation group on the bone,L4、5 and L5、6 intervertebral disks acted as experimental group;L3、4 and L6、7 acted as self-control group.In the operation on the soft tissue,L4、5 and L5、6 acted as experimental control group.One,two,four and eight months post-operation,histological and ultrastructure organizations of intervertebral disks of New-Zealand rabbits were performed.[Result]The normal rabbit discs formed a very complex system,with an outer anulus fibrosus surrounding a central nucleus pulposus in which collagen fibers aligned parallelly and intervertebral disk cells distributed evenly.Collagen fibers derangly aligned and intervertebral disk ceils declined with time post-operation.At the end of four months post-operation,many degenerative cells were found in the study group,which features as irregular cell contours,swelling chondrosome,rough endoplasmic reticulum,and condense nucleus located in the cellular nucleus.Eight months after operation,many dead cells were found.Cytolysosomes increased,cellular nucleus became twisted,rough endoplasmic reticulums swelled,and chondrosome became vacuolization.Dead intervertebral disk cells were located in nidi which were made of multilayer degenerative collagen fibers.[Conclusion]Histological changes of intervertebral disk degeneration can be induced by destroying L4、5 and L5、6 zygapophysial joints of New-Zealand rabbit.