An Experimental Research On Adjacent Segment Degeneration After Anterior Cervical Corpectomy And Interbody Fusion

Background:Anterior cervical discectomy and interbody fusion was implemented by Smith and Robison in 1958 for cervical disc degeneration disease,and its outcome is sure.With more and more operation of this sort,experts find more and more adjacent segment degeneration(ASD) above or under the fusion levels because of accumulative stress.So an un-fusion technique was carried out to try to solve the problem.The first cervical artificial disc prototype was created and implanted by Fernstrom in 1966.Eight patients had 13 corrosion-resistant,stainless steel ball-shaped prostheses with diameters of 6 to 10 mm implanted.But the study lacked long-term follow-up,and these artificial discs later were abandoned due to problems such as subsidence of the device and segmental hypermobility.Proximity to the spinal cord,size constraints,and the functional complexity of the intervertebral disc have slowed the development of cervical arthroplasty and its implementation into clinical practice.Interest in cervical arthroplasty underwent a resurgence in the 1990s.The first Bryan cervical disc,A new type of metal-on-plastic artificial disc,was implanted in January 2000; since then,more than 6000 patients have been treated with this device.A number of new cervical devices are providing the possibility that neuronsurgeons will have multiple alternatives to cervical fusion in the near future.More and more artificial cervical devices have been used in China in recent years.Their short-term clinical outcome is encouraging,but there are insufficient evidences to show they can prevent adjacent segment degeneration for lackage of long-term follow-up.As same,there are no sufficient evidences to stop its widespread in the clinical use.The trial is to observe adjacent segment degeneration after anterior cervical corpectomy and interbody fusion on goats.With aging,biomechanical change after spinal operation and trauma,more sympotomatic disc degeneration diseases can be seen.The value and successful rate is sure,but its complications such as internal fixation failure,pseudoarthrodesis,infection show the risk of the operation.With deeper recognization of intervertebral disc disease and progress of Protocols in Molecular Biology,proper biological intervene on degenerative discs can delay or even reverse its degeneration procedure.Building a animal-model of goats for the study of genetic therapy is another objective of the topic.To mimic human cervical spine surgery more accurately,it had better make use of non human primate as models.However these animals are expensive,limited supplying and difficult to handle,many scholars use goats,sheep and swines as animal models,Goats are chosen as animal models for anterior cervical interbody fusion,because they are the most optimal ones.The biomechanics environment of goats' cervical spine and the size of their discs and vertebrae are similar to human beings.Objective:To observe the change of adjacent discs after anterior cervical interbody fusion in goats,and provide theoretic evidence for clinical treatment of further experimental study.Methods:To select 14 goats as experimental animals,observe the change of adjacent discs after anterior cervical interbody fusion,through x-ray film,MRI and by analyzing adjacent discs with immunohistochemistry and polymerase chain response(PCR).Experimental groups are divided into post-op 3 months and post-op 6 months,and respective control group is designed.Results:The result from the experiment is the degeneration between experimental groups and control groups is statistically disguishing.It's testified not only by MRI and X-ray film but also by PCR and immunohistochemistry test of disc tissue.Conclusions:1.Adjacent segment degeneration is not only related to aging but also strongly related to fusion technology.2.It constructs a degenerative animal model to further experimental study.