Facet-occiput slope angle: A novel predictor of cage placement feasibility during surgery in basilar invagination patients.

Background and aim: Direct posterior reduction and manipulation of the C1-2 joints, accompanied by placement of spacers, is the state-of-the-art technique for treating basilar invagination (BI) and atlantoaxial dislocation (AAD). The hindrance of occiput to reaching up to the true atlantoaxial facets (AAF) during the surgery remains challenging for cage placement. The aim of this study was to explore an objective and precise method of measuring the effect of the hindrance of occiput to reaching up to the true AAF and cage placement during surgery. Method: We collected the clinico-imaging data of 58 patients with BI and AAD (Group A) who underwent surgery in our hospital, and 78 control cohorts (Group B) were retrieved retrospectively. We measured facet-occiput slope angle (FOSA) in midsagittal CT. Patients were positioned prone for surgery based on preoperative flexion O-C2a, and access to the true AAF was observed intraoperatively. The cut-off value of FOSA for the feasibility of cage placement in BI and AAD patients was appointed when access to the true AAF was impossible due to the hindrance of occiput during surgery. Results: The cut-off value of FOSA for the feasibility of cage placement was 34o with an area under the curve AUC of 0.800 (95 % CI: 0.672-0.928, P < 0.001) and the Youden index of 0.607. In patients with FOSA >34o, reaching up to the true AAF and 3D-printed cage placement was impossible. FOSA was negative in Group A and positive in Group B, significantly larger in females compared to males in both groups and significantly larger postoperatively in Group A. Conclusion: FOSA can objectively measure the feasibility of cage placement when the patient is positioned prone per preoperative flexion O-C2a. A FOSA >34o is contraindication for cage placement.

Efficacy of computed tomography-assisted limited decompression in the surgical management of thoracolumbar fractures with neurological deficit.

OBJECTIVE: To investigate the effect of CT-assisted limited decompression in managing single segment A3 lumbar burst fracture. METHOD: A retrospective study (January 2015-June, 2019). One hundred six cases with single-level Magerl type A3 lumbar burst fractures treated with short-segment posterior internal fixation and limited decompression. Patients were divided into two groups: CT-assisted group and non-CT-assisted group. Perioperative factors, clinical outcomes, post-operative complications, imaging parameters, and health-related quality of life (HRQoL) were evaluated. RESULTS: Kyphosis, loss of anterior and posterior vertebral body heights, operative time, and post-operative complications were not significantly different between the two groups. The visual analog score (VAS) and spinal canal encroachment in the CT-assisted group were lower compared with the non-CT-assisted group (p < 0.05). The Japanese Orthopaedic Association (JOA) score, the simplified HRQoL scale, and the American Spinal Injury Association (ASIA) Spinal Cord Injury Grade in the CT-assisted group were significantly higher compared with the non-CT-assisted group (p < 0.05). CONCLUSION: CT-assisted limited decompression in the treatment of single-segment A3 lumbar burst fracture can achieve better fracture reduction and surgical results and improve the long-term recovery of the patients' neurological function and quality of life.

Cervical instability in cervical spondylosis patients : Significance of the radiographic index method for evaluation.

BACKGROUND: Cervical spondylosis is one of the most common causes of cervical instability. Various methods are used for measuring cervical instability on X­ray films. The purpose of this study was to assess the application of the radiographic index method to analyze the radiographic features of cervical spondylosis instability. MATERIAL AND METHODS: Digitized dynamic radiographs of 121 subjects with cervical spondylosis were retrospectively retrieved. The cervical spondylosis patients were divided into two groups according to the symptoms: patients with positive neurological deficits with and without neck symptoms (group I, n = 62) and patients with neck symptoms only (group II, n = 59). A total of 62 healthy subjects were assigned to the control group (group III). The radiographic indices of cervical curvature, the full flexion to full extension ranges of motion (ROM) and horizontal displacement of the three groups were analyzed and compared with each other. RESULTS: On flexion-extension views there were significant differences (p = 0.00000 [significance of cervical lordosis on flexion view between the three groups], p = 0.00271 [significant difference of cervical lordosis between the three groups on extension view]) between the three groups concerning the cervical lordosis: group I had the least cervical curvature, followed by group II and group III. The full flexion to full extension ranges of motion for group I was significantly decreased (p = 0.0039) when compared with group II and group III. The horizontal displacement at each segmental level (except C2/C3) was significantly higher in group I than that of the other two groups. CONCLUSION: With the application of the radiographic index method, cervical spine lordosis, the full flexion to full extension ROM, horizontal displacement, and cervical instability can be accurately illustrated. Cervical spondylosis is an age-related, wear and tear change of the spine that occurs over time. The index of the horizontal displacement ≥0.3 is suggestive of cervical instability.