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 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.
Objective To evaluate the clinical effect of Halo-vest in treatment of unstable upper cervical spine. Methods From March 1997 to October 2002, 16 cases of unstable upper cervical spineswere treated and immobilized by Halovest, aged from 14 to 53 years. There were 3 cases of isolated Jefferson fractures, 4 cases of isolated Hangman fractures and 1 case of Anderson type Ⅱ fracture. The 8 cases were immobilized for 3-4 months by Halovest. There were 3 cases of old odontoid fractures with dislocations treated by occipitocervical plate fixation and fusion, 1 case of C1 malignant tumor by posterior resection and internal fixation, 2 cases of C2 malignant tumor by anterior resection, fusion, and internal fixation; these cases were immobilized by Halo-vest during surgery. There were 1 case of C2,3 tuberculosis were treated by anterior debridement and fusion, and 1 case of gooseneck deformity by anterior decompression, fusion and screw fixation after resection of C2-7 , the 2 cases were immobilized for 3 months by Halo-vest.Of 16 cases, there were 8 cases accompanied with spinal cord syndrome. Results Fifteen cases were followed up 6 months to 5 years. Anterior arch ununion and posteriorarch osseous healing occurred in 1 case of Jefferson fracture. Other fractures and embedded bones became osseous fusion. One case of C2 malignant tumorrecurred 8 months after operation. Spinal cord syndrome of all patients disappeared. Conclusion Halo-vest immobilization is an effective method for conservative treatment and stable reconstruction of unstable upper cervical spine.
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 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.
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.
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.
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 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.
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.