BACKGROUND: The anterior thoracolumbar internal fixation devices can be divided into two main categories: the stick system such as kaneda,and the plate system such as Z-plate. Both categories have satisfactory biomechanical properties, but the devices of these types are all imported and so expensive that they exceed the affordability of domestic patients:Based on various anterior throacolumbar internal fixation devices and the spinal characteristics of the Chinese people, the author designed a new brand of anterior thoracolumbar internal fixation device for Chinese people:New Ti-plate (NTP).OBJECTIVE: Biomechanical properties of three anterior thoracolumbar internal fixation devices were compared in an attempt to provide a scientific and theoretical basis for clinical applications.DESIGN: A sampling investigation.SETTING: The Department of Orthopaedics of the Second Affiliated Hospital of Soochow University and Department of Radiology of Nantong Hongqiao Hospital.PARTICIPANTS: This study was carried out at the Biomechanical Engineering Research Institute of Shanghai University between May and August 2003. Fifteen fresh spinal samples from the healthy adults (T12-S1) were used in this study.METHODS: Fifteen spinal (T12-S1) specimens were obtained from fresh bodies to induce injuries to anterior and middle columns, which were fixed with Dunn Ⅲ, NTP and Z-plate respectively to compare the strength, rigidity, and the stability of the spine.MAIN OUTCOME MEASURES: Changes of load-straining and loaddisplacement of the three groups of specimens under the conditions of axial decompression, anteflection, post-extention, and lateral flexion.RESULTS: Fifteen fresh adult spinal specimens were involved in this study and all entered the stage of result analysis. Under the maximal load of 500 N,the average straining for Z-plate, NTP and Dunn Ⅲ was 410 uε,430 uε, 477 uε respectively. The average longitude displacement for the above three devices was 2.23 mm, 2.38 mm and 2.85 mm respectively.The thoracolumbar fracture was fixed with three anterior internal fixation devices and it was proved that Z-plate and NTP fixations were better than fixation with Dunn Ⅲ in respect of spinal strength, rigidity and stability (P ＜ 0.05), but the difference between Z-plate and NTP had no statistical significance (P ＞ 0.05).CONCLUSION: NTP and Z-plate devices are conformed to the spinal biomechanical principles and were capable of reconstructing spinal biomechanical stability effectively, and it is a preferable anterior spinal internal fixation device.

1.The sagittal and transverse diameters of 1,456 transverse foramina in 728cervical vertebrae were measured.The data are as follows:transverse diameter(mm) sagittal diameter (mm)Left Right Left RightMale(702 cases) 6.0?1.0 5.9?1.1 5.4?1.2 5.3?1.1Female(754 cases) 5.9?1.0 5.8?1.1 5.3?1.1 5.1?1.12.Among the 710 transverse foramina of 357 cervical vertebrae observed,mostof them are of the elliptical type.3.19.3% of double transverse foramen were found in 710 transverse foraminawhich were mostly encountered at the 6 th cervical vertebra.4.The mean value of the external diameter of the cervical part of the vertebralartery is 4?0.7mm.in 40 sides of specimens.5.63.1% of the vertebral artery in the 710 transverse foramina were foundmedial to its accompanying vein.6.According to the relationship between the sagittal(X_1)and transversediameter(X_2)of the transverse foramen and the diameter(Y)of the vertebralartery,a formula,(?)=1.859+0.172 X_1+0.24 X_2,of multiple regression was formulatedThus,the estimated diameter of the vertebral artery from the sagittal diameter X_1and transverse diameter X_2 of the transverse foramen could be obtained and it maybe helpful for clinical practice.7.In case of arthrosis,the vertebral artery could be compressed by the unco-vertebral joint which are found mostly at the level of the 4～5th cervicalvertebrae.

BACKGROUND: Autogenous bone has been used in cervical vertebra graft bone fusion in earliest stage and at most. However, its source is limited, simultaneously, induced many complications such as infection, hemorrhage and postoperative pain in the donor bone region. Recently, above-mentioned complications were avoided or reduced with the usage of new graft bone fusion material. OBJECTIVE: To compare clinical efficacy using MC+~R combination of autogenous bone or calcium sulfate artificial bone in antador cervical fusion.METHODS: A total of 26 patients (34 levels) with cervical spondylotic myelopathy underwent anterior cervical discectomy and cervical intervertebral fusion from January to December 2008. Anterior cervical oblique cut was 3.0-4.0 cm. The endplate were preserved after the cervical intervertebral disc and the posterior longitudinal ligament were removed. Autogenous bone group was filled with autogenous bone. Calcium sulfate artificial bone group was filled with Wdght's Osteoset artificial bone. Anchoring clip was implanted between the cervical vertebrae. Every patient had a short neck incision was assessed with X-ray, JOA grade and Odom's evaluation scale.RESULTS AND CONCLUSION: The two groups of 26 patients (34 segments)were followed up. The JOA score of postoperation was no significant difference between the two groups. According to the Odom's evaluation scale, the excellent and good rate of calcium sulfate group was higher than autogenous bone group, but there was not statistical significance (P>0.05). The fusion rate of autogenous bone group was higher than calcium sulfate group at 3 and 6 months, but the fusion rate of two groups were 100% at 12 months. Although the calcium sulfate group at 6 months, lordosis angle lost more than 0.4°than the autogenous bone group,but no significant statistically between the two groups (P>0.05). MC+ combination of autogenous bone or Calcium sulfate had the same clinical efficacy in the treatment of cervical spondylotic myelopathy, but the calcium sulfate artificial bone could be effectively avoided the complications of donor site.