BACKGROUND: Upper cervical complex fractures are associated with high rates of neurological damage and mortality. The Dickman\'s classification is widely used in the diagnosis of upper cervical complex fractures. However, it falls short of covering the full spectrum of complex fractures. This limitation hinders effective diagnosis and treatment of these injuries.
OBJECTIVE: To address the diagnostic gap in upper cervical complex fractures, the study introduces a novel classification system for these injuries, assessing its reliability and usability.
METHODS: Proposal of a new classification system for upper cervical complex fractures.
METHODS: The study comprised the clinical data of 242 patients with upper cervical complex fractures, including 32 patients treated at our hospital, along with an additional 210 cases from the literature.
METHODS: The inter-observer and intra-observer reliability (kappa coefficient, κ) of this classification system were investigated by 3 spine surgeons. The three researchers independently re-evaluated the upper cervical complex fracture classification system 3 months later.
METHODS: The proposed classification categorizes upper cervical complex fractures into three main types: Type I combines odontoid and Hangman\'s fractures into two subtypes; Type II merges C1 with odontoid/Hangman\'s fractures into three subtypes; and Type III encompasses a combination of C1, odontoid, and Hangman\'s fractures, divided into two subtypes. Meanwhile, a questionnaire was administered in 15 assessors to evaluate the system\'s ease of use and clinical applicability.
RESULTS: A total of 45 cases (18.6%) unclassifiable by Dickman\'s classification were successfully categorized using our system. The mean κ value of inter-observer reliability was 0.783, indicating substantial reliability. The mean κ value of intra-observer reliability was 0.862, indicating almost perfect reliability. Meanwhile, thirteen assessors (87.7%) stated that the classification system is easy to remember, easy to apply, and they expressed intentions to apply it in clinical practice in the future.
CONCLUSIONS: This system not only offers high confidence and reproducibility but also serves as a precise guide for clinicians in formulating treatment plans. Future prospective applications are warranted to further evaluate this classification system.

UNASSIGNED: To 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.
UNASSIGNED: The 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 C 1 and C 2. 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.
UNASSIGNED: 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).
UNASSIGNED: The 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.
UNASSIGNED: 探讨保留棘上韧带连续性的改良椎板回植技术治疗上颈椎椎管内良性肿瘤的疗效及对颈椎稳定性的影响。.
UNASSIGNED: 回顾分析2012年1月—2021年1月收治的13例上颈椎椎管内良性肿瘤患者临床资料。男5例，女8例；年龄21～78岁，平均47.3岁。病程6～53个月，平均32.5个月。肿瘤位于C 1、C 2之间。术后病理检查示神经鞘瘤6例、脊膜瘤3例、神经节细胞瘤1例、神经纤维瘤2例、血管母细胞瘤1例。术中保留棘上韧带的连续性，在椎板外缘切开后掀起椎板韧带复合体显露椎管，切除椎管内肿瘤后椎板回植固定。手术前后于三维CT上测量寰齿前间距（atlantodental interval，ADI），采用日本骨科协会（JOA）评分评价疗效，采用颈椎功能障碍指数（NDI）评估颈椎功能，并记录颈椎总体旋转度。.
UNASSIGNED: 手术时间117～226 min，平均127.3 min；术中出血量190～890 mL，平均227.8 mL。患者肿瘤均完全切除，无椎动脉损伤、神经功能障碍加重、硬膜外血肿、感染等相关并发症发生；术后2例出现脑脊液漏，经补充电解质及切口局部加压处理后愈合。13例均获随访，随访时间14～37个月，平均16.9个月。影像学检查示肿瘤无复发，椎板无移位，内固定物无松动、移位，无继发椎管容积减小。末次随访时，JOA评分较术前显著改善（ P<0.05），获优8例、良3例、中2例，优良率84.6%；手术前后ADI、颈椎总体旋转度及NDI比较差异均无统计学意义（ P>0.05）。.
UNASSIGNED: 采用保留棘上韧带连续性的改良椎板回植技术治疗上颈椎椎管内良性肿瘤，可恢复椎管正常解剖结构，较好地保持了颈椎稳定性。.

OBJECTIVE: This review aimed to describe the preoperative management and postoperative complications associated with transoral decompression of the upper cervical spine, and to clarify the risk factors, related issues and complication management.
METHODS: Studies on transoral decompression for the upper cervical spine were reviewed systematically. The preoperative management and postoperative complications associated with transoral decompression for upper cervical deformities were analyzed.
RESULTS: Evidence suggests that preoperative management in patients undergoing transoral decompression for the upper cervical spine is closely related to the occurrence of postoperative complications. Hence, preoperative surgical planning, preoperative preparation, and oral nursing care should be seriously considered in these patients. Moreover, while being established as an effective and safe method, transoral decompression is associated with several postoperative complications, which could be prevented by elaborate preoperative management, improved surgical skills, and appropriate precautionary measures.
CONCLUSIONS: The effectiveness and safety of transoral decompression has been improved by the constant development of operative techniques and advanced auxiliary diagnostic and therapeutic methods, with the understanding of the anatomical structure of the craniocervical joint. Therefore, the incidence rates of postoperative complications have decreased. The application of individualized anterior implants and less-invasive endoscopic endonasal approach has improved the effectiveness of transoral decompression and reduced the associated complications.

BACKGROUND: This retrospective study aimed to determine the feasibility and efficacy of endoscopy-assisted anterior cervical debridement combined with posterior fixation and fusion in patients with upper cervical spine tuberculosis.
METHODS: Between June 2008 and January 2016, 17 patients (10 men and 7 women) with upper cervical spine tuberculosis underwent endoscopy-assisted anterior cervical debridement combined with posterior fixation and fusion. Anti-tuberculosis treatment was administered for 2-4 weeks preoperatively and 12-18 months postoperatively. The clinical and radiographic data of the patients were analyzed.
RESULTS: The operation was successfully completed in all patients. Neck pain and stiffness were relieved after the surgery in all patients. The mean operation time was 210.0 ± 21.2 min, and the mean intraoperative blood loss was 364.7 ± 49.6 mL. The mean follow-up duration was 68.1 ± 6.7 months. The erythrocyte sedimentation rate returned to normal by 3 months postoperatively. Visual analog scale scores for neck pain were significantly lower postoperatively than preoperatively. All patients had significant postoperative neurological improvement. Patient-reported outcomes, as measured using the Kirkaldy-Willis criteria, were as follows: excellent, 12 patients; good, 4 patients; fair, 1 patient; and poor, 0 patients. Bone fusion was achieved at 10.9 ± 1.9 months after the surgery; no cases of instrument loosening or fracture occurred.
CONCLUSIONS: Endoscopy-assisted anterior cervical debridement combined with posterior fixation and fusion is a feasible and effective surgical method for the treatment of upper cervical spine tuberculosis. It can be used to restore upper cervical spine stability and facilitate spinal healing.

A retro-odontoid pseudotumor (ROP) is commonly associated with atlantoaxial instability or rheumatoid arthritis. However, ROP in the absence of atlantoaxial instability or rheumatoid arthritis, which is termed idiopathic ROP (IROP), is a rare condition. The pathomechanisms and optimal treatment strategies for IROP remain controversial. The aim of the present study was to evaluate the radiographic and clinical characteristics of IROP patients and to assess the efficiency of atlantoaxial/occipitocervical fusion on IROP regression.
Data from 5 patients diagnosed with IROP were retrospectively reviewed. Posterior atlantoaxial or occipitocervical fixation and fusion were performed in 4 patients and C1 posterior arch resection alone in 1 patient. The patients\' features, surgical procedures, and complications were recorded. The retro-odontoid soft tissue thickness was measured on preoperative and postoperative magnetic resonance imaging to evaluate IROP regression.
The mean follow-up time was 37 months. ROP regression was achieved in patients who received atlantoaxial/occipitocervical fusion, but not for the patient with C1 posterior resection alone. There were no observed neurovascular complications associated with surgery.
IROP was related to a restricted range of motion of the subaxial spine. Upper cervical fixation is an optional treatment that produces IROP regression over time. By contrast, direct removal of the IROP is unnecessary.

BACKGROUND: The finite element method (FEM) is an efficient and powerful tool for studying human spine biomechanics.
OBJECTIVE: In this study, a detailed asymmetric three-dimensional (3D) finite element (FE) model of the upper cervical spine was developed from the computed tomography (CT) scan data to analyze the effect of ligaments and facet joints on the stability of the upper cervical spine.
METHODS: A 3D FE model was validated against data obtained from previously published works, which were performed in vitro and FE analysis of vertebrae under three types of loads, i.e. flexion/extension, axial rotation, and lateral bending.
RESULTS: The results show that the range of motion of segment C1-C2 is more flexible than that of segment C2-C3. Moreover, the results from the FE model were used to compute stresses on the ligaments and facet joints of the upper cervical spine during physiological moments.
CONCLUSIONS: The anterior longitudinal ligaments (ALL) and interspinous ligaments (ISL) are found to be the most active ligaments, and the maximum stress distribution is appear on the vertebra C3 superior facet surface under both extension and flexion moments.

OBJECTIVE: This study was performed to introduce posterior laminectomy and pedicle screw fixation for the treatment of upper cervical spinal cord tumors and investigate the curative effects.
METHODS: Eighteen patients (11 men, 7 women) who underwent surgical treatment of an upper cervical intraspinal tumor from January 2008 to June 2013 were reviewed. Clinical parameters including age, sex, affected spinal levels, lesion location, duration and type of symptoms, and pathological features were retrospectively investigated.
RESULTS: The mean operation time was 181.9 ± 25.5 minutes (range, 135-240 minutes), and the mean blood loss volume was 1038.9 ± 284.2 mL (range, 750-1530 mL). The Frankel grade, Japanese Orthopaedic Association score, and Karnofsky performance status score were significantly better postoperatively than preoperatively. The radiographic examination revealed good bone graft fusion. Two patients developed tumor recurrence, while four patients developed intraoperative or postoperative complications.
CONCLUSIONS: Management of upper cervical intraspinal tumors by posterior laminectomy and pedicle screw fixation can relieve compression of the cervical cord and nerve root, thoroughly remove the tumor lesion, reconstruct the stability of the upper cervical spine, and improve patients\' quality of life.

Ossification of the ligamentum flavum (OLF) is rarely observed in the cervical spine, particularly not in the upper cervical spine. The present report describes two cases of OLF combined with cervical myelopathy and provides a literature review with a comparative analysis of previous studies and the present cases. Pre-operative CT, MRI and histological examination were performed to confirm the diagnosis of these patients (A 37-year-old female and 63-year-old male). In both cases, histological examination of surgical specimens revealed OLF. The symptoms of the two patients significantly improved after surgery and no recurrence was observed at 13 months after surgery. Furthermore, the clinical outcomes were satisfactory and the internal fixation was solid in the two cases. Review of the literature suggested that further research is required to reveal the optimal treatment methods for upper cervical OLF.

BACKGROUND: For patients with spinal canal stenosis in the upper cervical spine who undergo C3-7 laminoplasty alone, it remains impossible to achieve full decompression due to its limited range. This study explores the extension of expansive open-door laminoplasty (EODL) to C1 and C2 for the treatment of cervical spinal stenosis of the upper cervical spine and its effects on cervical sagittal parameters.
METHODS: A retrospective analysis of 33 patients presenting with symptoms of cervical spondylosis myelopathy (CSM) and ossification in the posterior longitudinal ligament (OPLL) of the upper cervical spine from February 2013 to December 2015 was performed. Furthermore, the changes in the C0-2 Cobb angle, C1-2 Cobb angle, C2-7 Cobb angle, C2-7 SVA, and T1-Slope in lateral X-rays of the cervical spine were measured before, immediately after, and 1 year after the operation. JOA and NDI scores were used to evaluate spinal cord function.
RESULTS: The C0-2 and C1-2 Cobb angles did not significantly increase (P = 0.190 and P = 0.081), but the C2-7 Cobb angle (P = 0.001), C2-7 SVA (P < 0.001), and T1-Slope (P < 0.001) significantly increased from preoperative to 1 year postoperative. In addition, C2-7 SVA was significantly correlated with the T1-Slope (Pearson = 0.376, P < 0.001) and C0-2 Cobb angle (Pearson = 0.287, P = 0.004), and the C2-7 SVA was negatively correlated with the C2-7 Cobb angle (Pearson = - 0.295, P < 0.001). The average preoperative and postoperative JOA scores were 8.3 ± 1.6 and 14.6 ± 1.4 points, respectively, indicating in a postoperative neurological improvement rate of approximately 91.6%. The average preoperative and final follow-up NDI scores were 12.62 ± 2.34 and 7.61 ± 1.23.
CONCLUSIONS: The sagittal parameters of patients who underwent EODL extended to C1 and C2 included loss of cervical curvature, increased cervical anteversion and compensatory posterior extension of the upper cervical spine to maintain visual balance in the field of vision. However, the changes in cervical spine parameters were far less substantial than the alarm thresholds reported in previous studies. We believe that EODL extended to C1 and C2 for the treatment of patients with spinal canal stenosis in the upper cervical spine is a feasible and safe procedure with excellent outcomes.

OBJECTIVE: To establish a dynamic three-dimensional (3D) model of upper cervical spine instability and to analyze its biomechanical characteristics.
METHODS: A 3D geometrical model was established after CT scanning of the upper cervical spine specimen. The ligament of the specimen was fatigued to establish the upper cervical spine-instability model. A 100-N preloaded stress was applied to the upper surface of the occipital bone, and then a 1.5-Nm moment was applied in the occipital-sagittal direction to simulate upper cervical spine flexion and extension. Subsequently, the 3D dynamic model was established based on trajectory data that were measured using a motion-capture system. The stress on the main ligament and the relative motion angle of the joint were analyzed.
RESULTS: The shape of the model grid was regular and the total number of its units was 627 000. After finite-element analysis was conducted, results of the ligament stress and relative movement angle were obtained. After the upper cervical spine instability, the pressure of the alar ligament during the upper cervical spine extension was increased from 2.85 to 8.12 MPa. The pressure of the flavum ligament was increased during the upper-cervical spine flexion, from 0.90 to 1.21 MPa. The pressure of the odontoid ligament was reduced during the upper cervical spine flexion and extension, from 10.46 to 6.67 MPa and 25.66 to 16.35 MPa, respectively. The pressure of the anterior longitudinal ligament and cruciate ligament was increased to a certain degree during upper cervical spine flexion and extension. The pressure of the anterior longitudinal ligament was increased during flexion and extension, from 7.70 to 10.10 MPa and 10.45 to 13.75 MPa, respectively. The pressure of the cruciate ligament was increased during flexion and extension, from 2.29 to 4.34 MPa and 2.32 to 4.40 MPa, respectively. In addition, after upper cervical spine instability, the articular-surface relative-movement angle of the atlanto-occipital joint and atlanto-axial joint had also changed. During upper cervical spine flexion, the angle of the atlanto-occipital joint was increased from 3.49° to 5.51°, and the angle of the atlanto-axial joint was increased from 8.84° to 13.70°. During upper cervical spine extension, the angle of the atlanto-occipital joint was increased from 11.16° to 12.96°, and the angle of the atlanto-axial joint was increased from 14.20° to 17.20°. Therefore, the movement angle of the atlanto-axial joint was most obvious after induction of instability.
CONCLUSIONS: The 3D dynamic finite-element model of the upper cervical spine can be used to analyze and summarize the relationship between the change of ligament stress and the degree of instability in cervical instability. Frequent or prolonged flexion activities are more likely to lead to instability of the upper cervical spine.