ObjectiveTo investigate the effectiveness of cervical pedicle screw implantation technique under regional method.MethodsThe clinical data of 85 patients who met the selection criteria between April 2010 and May 2018 were retrospectively analyzed. There were 57 males and 28 females, aged 35-68 years, with an average of 57.6 years. Among them, there were 10 cases of ossification of posterior longitudinal ligament, 68 cases of cervical spondylosis with multilevel stenosis, 3 cases of cervical tumor, 1 case of congenital malformation, and 3 cases of cervical trauma; the lower cervical spine lesions involved C3-C7. Preoperative Frankel spinal cord injury grading: 2 cases of grade C, 51 cases of grade D, and 32 cases of grade E. Cervical pedicle screw implantation technique under regional method was performed with a total of 618 pedicle screws. Postoperative changes in neurological symptoms were observed; cervical mouth opening anteroposterior and lateral X-ray films and cervical CT examinations were performed to evaluate the pedicle screws position.ResultsThe operation time was 2.5-4.0 hours, with an average of 3.0 hours. The intraoperative blood loss was 180-550 mL, with an average of 345 mL. No intraoperative vascular or nerve injury occurred. The patients with neurological symptoms were relieved to varying degrees. There were 2 cases of superficial incision infection after operation, the wound healed after enhanced dressing change. The postoperative hospital stay was 5-14 days, with an average of 8.4 days. At discharge, Frankel neurological grading was grade D in 26 patients and grade E in 59 patients. All the patients were followed up 6-24 months, with an average of 13 months. At last follow-up, cervical X-ray films showed the good pedicle screw fixation without loosening. Cervical CT evaluated the position of pedicle screws: 523 pedicle screws (84.7%) in grade Ⅰ, 80 (12.9%) in grade Ⅱ, and 15 (2.4%) in grade Ⅲ; the accuracy rate of the screw position was 97.6%.ConclusionCervical pedicle screw implantation technique under regional method can significantly improve the success rate of screw implantation. It is easy to operate, does not destroy the bone cortex, and has stable fixation.
ObjectiveTo review the present situation of experimental study and clinical application of middle and lower cervical anterior transpedicular screw (CATPS) fixation. MethodsThe literature on the CATPS fixation was reviewed and summarized. ResultsThere is a safe area to implement the CATPS fixation and anterior decompression, and fusion can be done at the same time. It can provide a new idea for surgical treatment of complex cervical disease. Although it has so many advantages, its complex operating methods and optimal design of plate should be attended. Long-term effectiveness and specific indications still should be researched. ConclusionMiddle and lower cervical anterior transpedicular screw is an effective and safe fixation for cervical diseases. But the time for clinical use is short, the long-term effectiveness, surgical technique, and internal fixation devices are still need further study.
ObjectiveTo observe the in vivo three-dimensional (3-D) transient motion characteristics of the subaxial cervical spine in healthy adults. MethodsSeventeen healthy volunteers without cervical spine related diseases were recruited for this study, including 8 males and 9 females with a mean age of 26 years (range, 23-41 years). The vertebral segment motion of each subject was reconstructed with CT, and Rhinoceros 4.0 solid modeling software were used for 3-D reconstruction model of the subaxial cervical spine. In vivo cervical vertebral motion in flexionextension, left and right bending, left and right rotation was observed with dual fluoroscopic imaging system (DFIS). Coordinate systems were established at the vertebral center of C3-7 to obtain the intervertebral range of motion (ROM) and displacement at C3, 4, C4, 5, C5, 6, and C6, 7. The X-axis pointed to the left along the coronal plane, the Y-axis pointed to the back along the sagittal plane, and the Z-axis perpendicular to the X-Y plane pointed to the head. The ROM along X, Y, and Z axises were represented by rotation in flexion-extension (α), in left-right bending (β), and in left-right twisting (γ) respectively, and the displacement in left-right direction (x), in anterior-posterior direction (y), and in proximaldistal direction (z), respectively. ResultsIn flexion and extension, the displacement in anterior-posterior direction of C6, 7 was significantly less that of other segments (P<0.05), but the displacements in left-right direction and in proximaldistal direction showed no significant difference between segments (P>0.05); the ROM values in flexion-extension of C4, 5 and C5, 6 were significantly larger than those of C3, 4 and C6, 7 (P<0.05), and the ROM value in left-right twisting of C4, 5 was significantly larger than those of C5, 6 and C6, 7 (P<0.05), but the ROM value in left-right bending showed no significant difference between segments (P>0.05). In left and right bending, there was no significant difference in the displacement between other segments (P>0.05) except that the displacement in anterior-posterior direction of C3, 4 was significantly larger than that of C4, 5 (P<0.05), and that the displacement in proximal-distal direction of C6, 7 was significantly less than that of C3, 4 and C4, 5 (P<0.05); no significant difference was shown in the ROM value between segments (P>0.05), except that the ROM value in left-right twisting of C3, 4 was significantly larger than that of C5, 6 and C6, 7 (P<0.05). In left and right rotation, the ROM value in left-right twisting of C3, 4 was significantly larger than that of C4, 5 and C6, 7 (P<0.05), and the displacement and ROM value showed no significant differece between other segments (P>0.05). ConclusionThe intervertebral motions of the cervical spine show different characters at different levels. And the 6-degree-of-freedom data of the cervical vertebrae are obtained, these data may provide new information for the in vivo kinematics of the cervical spine.
ObjectiveTo investigate the relationship between O-EA angle and lower cervical curvature in patients with anterior atlantoaxial dislocation undergoing occipitocervical fusion, and to analyze the effect of O-EA angle on lower cervical curvature.MethodsThe clinical data of 61 patients with anterior atlantoaxial dislocation undergoing occipitocervical fusion who were admitted between April 2010 and July 2018 and met the selection criteria were retrospectively analyzed. There were 32 males and 29 females, with an age of 14-76 years (mean, 50.7 years). The fixed segment included 19 cases of C0-C2, 27 cases of C0-C3, 14 cases of C0-C4, and 1 case of C0-C5. The O-EA angle, C2-7 Cobb angle, and T1 tilt angle were measured before operation and at last follow-up. According to the O-EA angle measured at last follow-up, the patients were divided into <95° group (group A), 95°-105° group (group B), and >105° group (group C), and compared the differences of gender, age, fixed segment (short segment was at C3 and above, long segment was beyond C3), and C2-7 Cobb angle. Correlation analysis between the O-EA angle and C2-7 Cobb angle before operation and at last follow-up, as well as the changes of O-EA angle and C2-7 Cobb angle between before operation and at last follow-up were analyzed.ResultsAll 61 patients were followed up 12-24 months, with an average of 22.4 months. There was no significant difference in O-EA angle, C2-7 Cobb angle, and T1 tilt angle before operation and at last follow-up (P>0.05). According to the last follow-up O-EA angle grouping, there were 14 cases in group A, 29 cases in group B, and 18 cases in group C. There was no significant difference in age, gender composition, and fixed segment composition among the three groups (P>0.05); the differences in C2-7 Cobb angles among the three groups were significant (P<0.05), groups A, B, and C showed a gradually increasing trend. The O-EA angle was positively correlated with C2-7 Cobb angle before operation and at last follow-up (r=0.572, P=0.000; r=0.618, P=0.000); O-EA angle change at last follow-up was also positively correlated with C2-7 Cobb change (r=0.446, P=0.000).ConclusionThe O-EA angle of patients with anterior atlantoaxial dislocation is positively correlated with C2-7 Cobb angle. Too large O-EA angle should be avoided during occipitocervical fixation, otherwise it may accelerate the degeneration of the lower cervical spine.
OBJECTIVE: To investigate surgical reconstruction of stability of lower cervical spine in children suffering trauma, tuberculosis and tumor. METHODS: From January 1998 to September 2001, 8 cases of unstable lower cervical spine were treated by operations, of anterior decompression, massive iliac bone grafting, posterior fixation with spinous process tension band wiring, and fusion with heterogeneous iliac bone grafting. RESULTS: With an average following up of 1 year and 9 months (6 months to 4 years and 3 months), 3 cases recovered excellently, 4 cases recovered well and 1 case died of pulmonary infection. CONCLUSION: The above results indicate that anterior decompression, massive iliac bone grafting, posterior fixation with spinous process tension band wiring and fusion with heterogeneous iliac bone grafting can be used as one of the methods to reconstruct the stability of lower cervical spine in children.
Objective To compare the biomechanical properties of the anterior transpedicular screw-artificial vertebral body (AVB) and conventional anterior screw plate system (AP) in lower cervical spine by finite element study. Methods CT images (C1-T1) were obtained from a 38-year-old female volunteer. The models of intact C3-7 (intact group), AP fixation (AP group), and AVB fixation (AVB group) were established and analyzed by Mimics 14.0, Geomagic Studio 2013, and ANSYS 14.0 softwares. The axial force of 74 N and moment couple of 1 N·m were loaded on the upper surface and upper facet joint surfaces of C3. Under conditions of flexion, extension, lateral bending, and rotation, the Von Mises stress distribution regularity and maximum equivalent stree of AP and AVB groups were recorded, and the range of motion (ROM) was also analyzed of 3 groups. Results The intact model of lower cervical spine (C3-7) was established, consisting of 286 382 elements and 414 522 nodes, and it was successfully validated with the previously reported cadaveric experimental data of Panjabi and Kallemeyn. The stress concentrated on the connection between plate and screw in AP group, while it distributed evenly in AVB group. Between AP and AVB groups, there was significant difference in maximum equivalent stress values under conditions of 74 N axial force, flexion, extension, and rotation. AVB group had smaller ROM of fixed segments and larger ROM of adjacent segments than AP group. Compared with intact group, whole ROM of the lower cervical spine decreased about 3°, but ROM of C3, 4 and C6, 7 segments increased nearly 5° in both AP and AVB groups. Conclusion As a new reconstruction method of lower cervical spine, AVB fixation provides better stability and lower risk of failure than AP fixation.
Objective To establ ish sophisticated three-dimensional finite element model of the lower cervical spine and reconstruct lower cervical model by different fixation systems after three-column injury, and to research the stress distribution of the internal fixation reconstructed by different techniques. Methods The CT scan deta were obtained from a 27-year-old normal male volunteer. Mimics 10.01, Geomagic Studio10.0, HyperMesh10.0, and Abaqus 6.9.1 softwares were usedto obtain the intact model (C3-7), the model after three-column injury, and the models of reconstructing the lower cervical spine after three-column injury through different fixation systems, namely lateral mass screw fixation (LSF) and transarticular screw fixation (TSF). The skull load of 75 N and torsion preload of 1.0 N•m were simulated on the surface of C3. Under conditions of flexion, extension, lateral bending, and rotation, the Von Mises stress distribution regularity of internal fixation system was evaluated. Results The intact model of C3-7 was successfully establ ished, which consisted of 177 944 elements and 35 668 nodes. The results of the biomechanic study agreed well with the available cadaveric experimental data, suggesting that they were accord with normal human body parameters and could be used in the experimental research. The finite element models of the lower cervical spine reconstruction after three-column injury were establ ished. The stress concentrated on the connection between rod and screw in LSF and on the middle part of screw in TSF. The peak values of Von Mises stress in TSF were higher than those in LSF under all conditions. Conclusion For the reconstruction of lower cervical spine, TSF has higher risk of screw breakage than LSF.