ABSTRACT
BACKGROUND: For patients with cervical spondylosis who fail to receive conservative treatment, cervical anterior decompression and fusion has always been the gold standard for surgical treatment. Since its use, it has been widely recognized by clinicians for its simple and convenient intraoperative operation and significant relief of pathological segmental symptoms after surgery. As time goes by, the problem of degeneration of surgery adjacent segments and loss of mobility of the replacement segments is gradually exposed. At the same time, the patient's requirements for postoperative rehabilitation and quality of life are constantly improving, and surgical technology continues to develop rapidly. This type of surgery cannot meet the clinical needs. Therefore, total cervical disc replacement surgery comes into being, which can solve the related problems caused by anterior cervical decompression and fusion, and the clinical effect is better than previous one. OBJECTIVE: To review the research status of artificial cervical intervertebral discs, to focus on its clinical effects and structure, and to prospect its improvement and development direction of artificial development direction. METHODS: A compute-based retrieval of CNKI, WanFang and PubMed databases was conducted for articles published between January 1995 and August 2019. The keywords were "non-fusion technique, artificial intervertebral disc, clinical efficacy, structure" in Chinese and English, respectively. The articles related to artificial cervical intervertebral disc were selected, and the latest experimental and clinical researches were preferred. RESULTS AND CONCLUSION: (1) Through analyzing the main artificial cervical discs on the market, the research of artificial cervical discs will focus on materials, structures, implantation devices and surgical approaches of prosthesis. The domestic cervical disc will be designed based on the anatomical features of the Chinese cervical spine. (2) It is believed that the future cervical disc replacement surgery will achieve a satisfactory clinical effect, and its postoperative complications will be significantly reduced, which can meet the requirements of Chinese people.
ABSTRACT
The mechanical properties of artificial intervertebral disc (AID) are related to long-term reliability of prosthesis. There are three testing methods involved in the mechanical performance evaluation of AID based on different tools: the testing method using mechanical simulator, specimen testing method and finite element analysis method. In this study, the testing standard, testing equipment and materials of AID were firstly introduced. Then, the present status of AID static mechanical properties test (static axial compression, static axial compression-shear), dynamic mechanical properties test (dynamic axial compression, dynamic axial compression-shear), creep and stress relaxation test, device pushout test, core pushout test, subsidence test, etc. were focused on. The experimental techniques using specimen testing method and testing results of available artificial discs were summarized. The experimental methods and research status of finite element analysis were also summarized. Finally, the research trends of AID mechanical performance evaluation were forecasted. The simulator, load, dynamic cycle, motion mode, specimen and test standard would be important research fields in the future.
ABSTRACT
ObjectiveTo study the range of movement (ROM) in adjacent vertebral segments and the changes in intervertebral disc stress after implanting artificial cervical disc. MethodA 3D finite element model for normal cervical spine was established using CT images scanned from a cadaver cervical spine. Simulation of bone graft and fusion of vertebral bodies as well as implantation of intervertebral disc prosthesis were performed between C5 and C6 . Then the ROM of adjacent functional spinal units (FSU, C4/5、C6/7) and the stress in C4/5 and C6/7 intervertabral disc were analyzed. Results（1）The model including the structures of ligaments, joint capsule and other soft tissue is built with high reality and accuracy；（2）Vertebral fusion increased movement range in adjacent FSU, and the stress in corresponding discs is significantly raised as well. The stress in nucleus pulposus and annulus fibrosus is increased about 70% at upper segment and 40% at lower segment; (3) After implantation of artificial disc, only the extension of cervicle spine is limited（P<0.05）; the stress in adjacent intervertebral disks is increased less than 10%. ConclusionsThe implanted artificial cervical disc can appropriately reduce the stress in adjacent vertebral segments, which is beneficial to improve the movement of the cervical spine.
ABSTRACT
@#Objective To observe the effects of rehabilitation exercises on limb function of patients with cervical spondylotic myelopathy (CSM) after artificial intervertebral disc replacement.Methods 42 CSM patients undergone anterior cervical decompression and Bryan disc prosthesis under microscope were randomly divided into the normal care group (n=20) and rehabilitation exercises group (n=22). All patients of two groups were assessed by JOA scale at 2nd week and 6th month after operation.Results The JOA scores of two groups at 6th month were all higher than that at 2nd week and scores of the rehabilitation exercises group were also higher than that of the normal care group ( P<0.01).Conclusion Rehabilitation exercises after artificial intervertebral disc replacement can improve spine cord function of CSM patient.