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.
In order to check the neck response and injury during motor vehicle accidents, we developed a detailed finite element model for human cervical spine C4-C6. This model consisted of cortical bone, cancellous bone, annulus, nucleus, ligaments and articular facet, and it also set up contact in the contacting parts for simulating the movement perfectly under frontal impact. This model could be used for stress and strain distribution after the frontal impact load was applied on this model. During the process of frontal impact, the most displacement simulated data were in the interval range of experimental data. The experimental results showed that this model for the human cervical spine C4-C6 simulated the movement under the frontal impact with fidelity, and reflected the impact dynamics response on the whole.
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.
ObjectiveTo investigate the effectiveness of percutaneous endoscopic posterior cervical Key-Hole fenestration decompression and nucleus pulposus extirpation in the treatment of paracentral cervical disc herniation.MethodsBetween December 2015 and October 2018, 29 cases of paracentral cervical disc herniation were treated with percutaneous endoscopic posterior cervical Key-Hole fenestration decompression and nucleus pulposus extirpation. There were 16 males and 13 females, with an average age of 49.7 years (range, 39-78 years). The disease duration was 3.5-15.0 months (mean, 6.2 months). The herniated disc located at C3, 4 in 2 cases, C4, 5 in 5 cases, C5, 6 in 9 cases, C6, 7 in 12 cases, and C7, T1 in 1 case. The main symptoms were radiculopathy symptom. The operation time, intraoperative blood loss, hospital stay, and complications were observed and recorded. Visual analogue scale (VAS) score, Japanese Orthopaedic Association (JOA) score, cervical range of motion (ROM), Macnab standard, and cervical segment stability were used to evaluate the efficacy and safety of the operation.ResultsAll patients were followed up 11-43 months, with an average of 19.4 months. The operation time was 67-89 minutes (mean, 73.3 minutes); the intraoperative blood loss was 18-30 mL (mean, 22.9 mL); the hospital stay was 5-10 days (mean, 7.3 days). All the incisions healed by first intention. There was 1 case of hypodynia and hyperalgesia in the affected limb after operation,1 case of decreased limb muscle strength. The VAS scores and JOA scores at each time point after operation were superior to those before operation (P<0.05). There was no significant difference between the time points after operation (P>0.05). At last follow-up, the effectiveness was rated according to the Macnab standard as excellent in 11 cases, good in 15 cases, fair in 2 cases, and bad in 1 case, with an excellent and good rate of 89.7%. The CT and MRI showed the decompression of spinal canal and nerve canal. There was no significant difference in cervical ROM between pre- and post-operation (t=1.427, P=0.165), and no surgical segment instability occurred by X-ray films of flexion and extension of cervical vertebrae.ConclusionFor the paracentral cervical disc herniation with simultaneous compression of nerve roots and spinal cord, percutaneous endoscopic posterior cervical Key-Hole fenestration decompression and nucleus pulposus extirpation has the advantages of small trauma, quick recovery, and satisfactory effectiveness, and can be used as a safe and effective minimally invasive procedure.
With the continuous deepening of the practice related to the concept of enhanced recovery after surgery, patients with cervical spondylosis have higher expectations and requirements for postoperative rehabilitation. In order to improve the rehabilitation of patients with cervical spondylosis, and increase patient satisfaction, the orthopedics team of West China Hospital of Sichuan University has formulated a program for early ambulation after anterior cervical spine surgery based on the concept of enhanced recovery after surgery. This article introduces the program from the definition, background, feasibility, significance, and specific content of early ambulation for patients undergoing anterior cervical spine surgery, and aims to provide experience and reference for future clinical practice.
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 investigate the effect of ultrasonic bone curette in anterior cervical spine surgery. MethodsA clinical data of 63 patients with cervical spondylosis who were admitted between September 2019 and June 2021 and met the selection criteria was retrospectively analyzed. Among them, 32 cases were operated with conventional instruments (group A) and 31 cases with ultrasonic bone curette (group B). There was no significant difference between the two groups (P>0.05) in gender, age, surgical procedure, surgical segment and number of occupied cervical space, disease type and duration, comorbidities, and preoperative Japanese Orthopaedic Association (JOA) score, cervical dysfunction index (NDI), and pain visual analogue scale (VAS) score. The operation time, intraoperative bleeding, postoperative drainage, postoperative hospital stay, and the occurrence of postoperative complications were recorded in both groups. Before operation and at 1, 3, and 6 months after operation, the JOA score and NDI were used to evaluate the function and the postoperative JOA improvement rate was calculated, and VAS score was used to evaluate the pain improvement. The anteroposterior and lateral cervical X-ray films were taken at 1, 3, and 6 months after operation to observe whether there was any significant loosening and displacement of internal fixators. ResultsCompared with group A, group B had shorter operation time and postoperative hospital stay, less intraoperative bleeding and postoperative drainage, and the differences were significant (P<0.05). All incisions healed by first intention in the two groups, and postoperative complications occurred in 5 cases (15.6%) in group A and 2 cases (6.5%) in group B, showing no significant difference (P>0.05). All patients were followed up 6-12 months (mean, 7.9 months). The JOA score and improvement rate gradually increased in groups A and B after operation, while the VAS score and NDI gradually decreased. There was no significant difference in VAS score between 3 months and 1 month in group B (P>0.05), and there were significant differences between the other time points of each indicator in the two groups (P<0.05). At 1, 3, and 6 months after operation, the JOA score and improvement rate in group B were better than those in group A (P<0.05). X-ray films examination showed that there was no screw loosening or titanium plate displacement in the two groups after operation, and the intervertebral cage or titanium mesh significantly sank. ConclusionCompared with traditional instruments, the use of ultrasonic bone curette assisted osteotomy in anterior cervical spine surgery has the advantages of shorter operation time, less intraoperative bleeding, less postoperative drainage, and shorter hospital stay.
This study aims to investigate the range of motion (ROM) and the stress variation in the intervertebral disc and the vertebral body on adjacent segments and the influence of force transmission mode after the dynamic cervical implant (DCI) surgery. Two types of surgery, DCI implantation and interbody fusion were used to establish the finite element model of the cervical C5, 6 segment degeneration treatment. The ROM and the adjacent discs and vertebral body stresses of two procedures under flexion, extension, lateral bending and axial rotation working conditions were analyzed. The results showed that ROM of the surgical segment in DCI model was well preserved and could restore to the normal ROM distributions (reduction of the amplitude was less than 25%), and the kinetic characteristics of adjacent segments was less affected. In fusion surgery model, however, ROM of the surgical segment was reduced by 86%-91%, while ROM, disc stress and vertebral stress of adjacent segments were increased significantly, and stress of the C5 vertebral body was increased up to 171.21%. Therefore DCI surgery has relatively small influence on cervical ROM and stress. The study provides a theoretical basis for DCI and fusion surgery in clinic.
ObjectiveTo investigate the feasibility of one-stage total spondylectomy by anterior and posterior approaches for treating solitary plasmacytoma (SP) of cervical spine.MethodsBetween June 2000 and March 2015, the clinical data, diagnosis, and treatment of 12 patients with SP of cervical spine were retrospectively analyzed. There were 8 males and 4 females, with a mean age of 46 years (range, 28-74 years). The mean disease duration was 8.4 months (range, 3-15 months). There were 2 cases in C2 segment, 4 cases in C3, 2 cases in C4, 1 recurrent case in C5, C6, and 3 cases in C7. According to WBB (Weinstein-Boriani-Biagini) surgical staging system, the tumor mainly occupied the vertebral body areas and expanded outside to 4 or 9 radiating zone in 8 cases, expanded both outsides to 4 or 9 radiating zones in 4 cases; 7 cases of them affected A to D layers, other 5 cases affected B to D layers. Preoperative Frankel system showed grade B in 1 case, grade C in 6 cases, and grade D in 5 cases. One vertebra segment was involved in 11 cases, and 2 vertebra segments were involved in 1 case. The unilateral vertebral artery was involved in 4 cases and bilateral vertebral artery in 1 case. One-stage total spondylectomy by anterior and posterior approaches for SP of cervical spine was applied in all patients, which all received adjuvant radiotherapy postoperatively. The operation time, intraoperative blood loss, complications, Frankel system, and visual analogue scale (VAS) score were recorded and analyzed.ResultsThe operation time was 6.8-9.3 hours (mean, 7.2 hours), and the intraoperative blood loss was 1 100-2 600 mL (mean, 1 600 mL). Esophageal leakage occurred in 1 patient with C5, C6 recurrent SP at 1 week after operation and 1 case presented with fat liquefaction of wound, who were cured by symptomatic treatment. Other patients showed no neurological deficit, major vascular injury (especially vertebral artery), phrenic nerve injury, superior laryngeal nerve injury, laryngeal nerve injury, respiratory failure, or other complications. All the 12 patients were followed up 27-98 months (mean, 58 months). The symptoms of spinal cord compression disappeared or improved after operation. At last follow-up, the nerve function was recovered to Frankel grade E in all patients; the VAS score decrease to 1.1±0.7, showing significant difference when compared with preoperative value (6.7±2.7) (t=2.485, P=0.014). Two patients had local recurrence at 29 months and 37 months after operation respectively, which were treated with adjuvant chemotherapy. One of them finally progressed to multiple myeloma and died of multiple organ failure after 43 months, the other one survived with residual tumor. One case presented with internal fixator loosening and breaking at 4 years after operation, who was performed revision surgery. The other patients had no tumor recurrence or malignant change during the follow-up, no complication such as internal fixator loosening or breaking occurred.ConclusionFor patients with SP of cervical spine, surgical intervention is an acceptable treatment option. One-stage total spondylectomy by anterior and posterior approaches can decline the local recurrence and relieve the symptoms of spinal cord compression, so as to improve patients’ life quality. However, patients with progression to multiple myeloma should be treated with individualized therapeutic regimen, and the prognosis may be poor.