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.
ObjectiveTo evaluate the effectiveness of modified recapping laminoplasty preserving the continuity of supraspinous ligament in the treatment of intraspinal benign tumors in upper cervical vertebrae and its influence on the stability of the cervical vertebrae. MethodsThe clinical data of 13 patients with intraspinal benign tumors in upper cervical vertebrae treated between January 2012 and January 2021 were retrospectively analyzed. There were 5 males and 8 females, the age ranged from 21 to 78 years, with an average of 47.3 years. The disease duration ranged from 6 to 53 months, with an average of 32.5 months. The tumors located between C1 and C2. Postoperative pathology showed 6 cases of schwannoma, 3 cases of meningioma, 1 case of gangliocytoma, 2 cases of neurofibroma, and 1 case of hemangioblastoma. During operation the continuity of the supraspinal ligament were retained, the lamina ligament complex was lifted to expose the spinal canal via the approach of the outer edge of the bilateral lamina, and the lamina was fixed after the resection of the intraspinal tumors. Before and after operation, the atlantodental interval (ADI) was measured on three-dimensional CT; the effectiveness was evaluated by Japanese Orthopaedic Association (JOA) score, the neck dysfunction index (NDI) was used to evaluate the cervical function, and the total rotation of the cervical spine was recorded. Results The operation time was 117-226 minutes (mean, 127.3 minutes); the intraoperative blood loss was 190-890 mL (mean, 227.8 mL). The tumors were completely removed in all patients. There was no vertebral artery injury, aggravation of neurological dysfunction, epidural hematoma, infection, or other related complications. Two patients occurred cerebrospinal fluid leakage after operation, which were healed through electrolyte supplement and local pressure treatment of incision. All the patients were followed up 14-37 months, with an average of 16.9 months. Imaging examination showed no recurrence of tumor, displacement of vertebral lamina, loosening and displacement of internal fixator, and secondary reduction of vertebral canal volume. At last follow-up, JOA score significantly improved when compared with preoperative scores (P<0.05). Among them, 8 cases were excellent, 3 cases were good, and 2 cases were medium, with an excellent and good rate was 84.6%. There was no significant difference in ADI, total rotation of the cervical spine, and NDI between pre- and post-operation (P>0.05). ConclusionThe treatment of intraspinal benign tumors in upper cervical vertebrae with modified recapping laminoplasty preserving the continuity of the supraspinous ligament can restore the normal anatomical structure of the spinal canal and maintain the stability of the cervical spine.
ObjectiveTo measure anatomical parameters related to cervical uncovertebral joint and provide data support for the design of uncovertebral joint fusion cage.MethodsAccording to the inclusion and exclusion criteria, raw DICOM data of cervical CT scan in 60 patients (30 males and 30 females, aged 39-60 years) were obtained, then the three-dimensional cervical spine model was reconstructed for anatomical measurement by using the Mimics19.0 software. The height of the uncinate process, the length of the uncinate process, the width of the uncinate process, and the length of the uncovertebral joint in the intervertebral foramen region were measured bilaterally from C3 to C7. The anterior and posterior distances between the uncinate processes were measured from C3 to C7. The height of the uncovertebral joint space, the central height of the intervertebral disc space, and the depth of the intervertebral disc space were also measured from C2, 3 to C6, 7. The mean, standard deviation, maximum, and minimum were calculated by using the SPSS22.0 statistical software for the design of uncovertebral joint fusion cage.ResultsThe height of the uncinate process, the length of the uncinate process, the width of the uncinate process, and the length of the uncovertebral joint in the intervertebral foramen region of C3-C7 and the height of the uncovertebral joint space of C2, 3-C6, 7 showed no significant difference between two sides (P>0.05). The height of the uncovertebral joint space also had no significant difference between females and males (P>0.05). The anterior distances between the uncinate processes of C3-C7 were significantly larger than the posterior distances between the uncinate processes (P<0.05), the uncovertebral joint presented a posterior cohesive shape. The central height of the intervertebral disc space in male group was slightly higher than that in female group, and the differences were significant (P<0.05) at C2, 3 and C5, 6; the depth of the intervertebral disc space in male group was significantly higher than that in female group (P<0.05). The central height of the intervertebral disc space was (4.94±0.49) mm (range, 3.81-5.90 mm), the depth of the intervertebral disc space was (15.78±1.23) mm (range, 12.94-18.85 mm), the anterior and posterior distances between the uncinate processes were (17.19±2.39) mm (range, 13.39-24.63 mm) and (10.84±2.12) mm (range, 7.19-16.64 mm), respectively. According to the results of the anatomical research, the height of the uncovertebral joint fusion cage was designed as 5, 6, 7, and 8 mm; the depth of the uncovertebral joint fusion cage was designed as 12, 13, 14, 15, and 16 mm; the width of the uncovertebral joint fusion cage was designed as 14-18 mm; and the two wings are designed as arc-shape with 2 and 3 mm in width.ConclusionThere are certain differences in the anatomical parameters of the uncovertebral joint between different segments. The uncovertebral joint fusion cage that designed based on the results of anatomical research is suitable for most patients.
This article reviews the progress of biomechanical studies on anterior cervical fusion and nonfusion surgery in recent years. The similarities and differences between animal and human cervical spines as well as the major three biomechanical test methods are introduced. Major progresses of biomechanical evaluation in anterior cervical fusion and nonfusion devices, hybrid surgery, coupled motion and biomechanical parameters, such as the instant center of rotation, are classified and summarized. Future development of loading method, multilevel hybrid surgery and coupling character are also discussed.
ObjectiveTo introduce and interpret ABCD classification system for subaxial cervical spine injury.
MethodsThe literature related to subaxial cervical spine injury classification system was extensively reviewed, analyzed, and summarized so as to introduce the ABCD classification system.
ResultsThe ABCD classification system for subaxial cervical spine injury consists of 3 parts. The first part of the proposed classification is an anatomical descri ption of the injury; it del ivers the information whether injury is bony, ligamentous, or a combined one. The second part is the classification of nerve function, spinal stenosis, and spinal instabil ity. The last part is optional and denotes radiological examination which is used to define injury type. Several letters have been used for simplicity to del iver the largest amount of information. And a treatment algorithm based on the proposed classification is suggested.
ConclusionThe ABCD classification system is proposed for simplification. However further evaluation of this classification is needed.
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.
A comprehensive, geometrically accurate, nonlinear C0-T1 three-dimensional finite element (FE) model was developed for the biomechanical study of human cervical spine and related disorders. The model was developed with anatomic detail from the computed tomography (CT) images of a 46-year old female healthy volunteer, and applied the finite element model processing softwares such as MIMICS13.1, Hypermesh11.0, Abaqus 6.12-1, etc., for developing, preprocessing, calculating and analysing sequentially. The stress concentration region and the range of motion (ROM) of each vertebral level under axial rotation, flexion, extension, and lateral bending under physiologic static loadings were observed and recorded. The model was proven reliable, which was validated with the range of motion in previous published literatures. The model predicted the front and side parts of the foramen magnum and contralateral pedicle and facet was the stress concentration region under physiological loads of the upper spine and the lower spine, respectively. The development of this comprehensive, geometrically accurate, nonlinear cervical spine FE model could provide an ideal platform for theoretical biomechanical study of human cervical spine and related disorders.
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.
Objective To study operative methods of treating upper cervical spine instability without injury. Methods Twentythree cases were treated by internal fixation with autologous bone grafts. Atlantoaxial arthrodesis were performed in 10 cases with Apofix interlaminar clamp(5 cases), Atlas cable system(3 cases) and Brookes(2 cases). Occipitocervical fusion were performed in the other 13 cases by using of CD-cervical(3 cases), Cervifix(8 cases) and Ustick fixation(2cases). Results All the 23 cases were followed up for 2.5 years in average (ranged from 6 months to 5 years). Solid arthrodesis was obtained in all 23 cases . Six months after operation, of the 20 cases with preoperation nervous lesion, improvement was achieved in 16 cases. According to JOA standard and Hirabashiformula,the rate of improvement was 27.1%.Conclusion Posterior fusion is recommended for upper cervical unstability.
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.
