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BACKGROUND: Cervical vertebra corpectomy decompression is one of the commonly used methods of anterior cervical decompression. In recent years, under the guidance of the principle of anterior cervical surgery, scholars propose the anterior cervical vertebra corpectomy decompression with preserving the posterior wall of the corpectomied vertebral body. It retains the posterior wall of the vertebral body, not only increases the stability of the cervical spine, but also increases the area of bone graft, which is conducive to the long-term fusion. At the same time, retaining posterior wall of the vertebral body can effectively prevent bone- and implant-induced spinal cord injury.OBJECTIVE: To evaluate the biomechanical stability of anterior cervical vertebra corpectomy decompression with preserving the posterior wall of the corpectomied vertebral body procedure on sheep by the establishment of finite element model with CT data.METHODS: Cervical vertebra specimens of adult sheep were selected, and scanned to capture its CT data. The geometrical model captured by CT was then transformed into finite element model through finite element software (without surgery). In the posterior wall preserving group, C4 corpectomy decompression was conducted while preserving its posterior wall followed by titanium-meshes and AO plate fixation. On the basis of posterior wall preserving group,corpectomy decompression was operated without preserving the posterior wall in another group; titanium mesh and plate were fixed. Finite element software was used to test and analyze the changes in stress and displacement of cervical vertebra under different conditions.RESULTS AND CONCLUSION: (1) The displacement was slightly small, and immediate postoperative stability was good in the posterior wall preserving group. However, the displacement and stress were not significantly different between posterior wall preserving group and posterior wall non-preserving group. (2) To sum up, a procedure preserving posterior wall of the vertebra body gains better immediate postoperative stability compared with conventional method.
RESUMEN
BACKGROUND:As a traditional treatment for multilevel cervical myelopathy,nterior long-segmental decompression has the shortcomings of great operative trauma,high difficulty,low fusion rate,etc.,which can affect the postoperative efficacy.OBJ ECTIVE:To evaluate the clinical effects of three different anterior surgeries on multilevel cervical myelopathy.DESIGN:A comparative observation.SETTING:Department of Orthopaedics,Changzheog Hospital,the Second Military Medical University of Chinese PLA.PARTICIPANTS:Thirty-six patients with multilevel cervical myelopathy of 3 consecutive segments,who were surgically treated,were selected from the Department of Orthopaedics,Changzheng Hospital,the Second Military Medical University of Chinese PLA from June 1999 to June 2003,including 25 males and 11 females,35-62 years of age,the disease course ranged from 3 to 26 months. According to the clinical manifestations and imaging esults,they were diagnosed as multilevel cervical myelopathy,and they were not suffering from consecutive ossification of posterior longitudinal ligament and ossification of ligamenta flava. Informed contents were obtained from all the patients and their relatives.METHODS:All the patients were grafted with utologous bone. Autologous ilium or cancellous bone excluding vertebral body was filled into titan net or Cage,which were made of titan and characterized by high intensity,tolerance to decay,good biocompatibility,etc. According to the operative manner,the patients were divided into 3 groups:① two-level corpectomy with fusion group(long-segmental decompression group,n =11):There were 4 cases grafted with long-titan net,and 7 cases grafted with autologous iliac bone. Sub-total two-level corpectomy with fusion was performed. ②segmental decompression group(n =16):including 12 cases of titan net+cage graft,4 cases of autologous bone+cage graft. One-level decompression and sub-total single corpectomy with fusion were performed. ③three-level decompression group(n =9):Only discectomy without corpectomy was performed. After complete decompression,3cages were used to fill artificial bone or grafted with autologous bone.MAIN OUTCOME MEASURES:Cervical anteroposterior and lateral radiographies,flexion and extension radiograph were reexamined within 1 week and at 3,6 and 12 months postoperatively. The neurological function was assessed using the Japanese Orthopaedic Association(JOA) scoring method preoperatively and 3 months postoperatively. The total score was 17 points,the higher the score,the better the neurological function. The duration of operation,perioperative bleeding amount,length of stay,cost of hospitalization,graft fusion at 3 months postoperatively,improved JOA score at 3 months postoperatively were recorded in the three groups. The occurrence of postoperative complications was observed by means of return visit.RESULTS:All the 36 patients with multilevel cervical myelopathy were involved in the analysis of results. The mean duration of operation,mean perioperative bleeding amount and mean length of stay in the segmental-decompression group and three-level decompression group were obviously fewer or shorter than those in the long-segmental decompression group(P ＜ 0.05),and the average cost of hospitalization was obviously higher than that in the long-segmental decompression group(P ＜ 0.05). The postoperative improved JOA score and graft fusion rate were close among the groups(P ＞ 0.05).CONCLUSION:Segmental anterior cervical decompression is a recommendable technique for multilevel cervical myelopathy by comprehensively considering the fusion rate,recovery of neurological function,duration of operation,perioperative bleeding and length of stay.