Lordosis distribution index for predicting mechanical complications after long-level fusion surgery: comparison of Global Alignment and Proportion score and Roussouly classification.

OBJECTIVE: Both the Global Alignment and Proportion (GAP) score and Roussouly classification account for the lordosis distribution index (LDI), but the LDI of the GAP score (G-LDI) is typically set to 50%-80%, while the LDI of the Roussouly classification (R-LDI) varies depending on the degree of pelvic incidence (PI). The objective of this study was to validate the ability of the G-LDI to predict mechanical complications and compare it with the predictive probability of R-LDI in patients with long-level fusion surgery. METHODS: A total of 171 patients were divided into two groups: 93 in the nonmechanical complication group (non-MC group) and 78 in the mechanical complication group (MC group). The mean age of the participants was 66.79 ± 8.56 years (range 34-83 years), and the mean follow-up period was 45.49 ± 16.20 months (range 24-62 months). The inclusion criteria for the study were patients who underwent > 4 levels of fusion and had > 2 years of follow-up. The predictive models for mechanical complications using the G-LDI and R-LDI were analyzed using binomial logistic regression and receiver operating characteristic analyses. RESULTS: There was a significant correlation between R-LDI and PI (r = -0.561, p < 0.001), while there was no correlation between G-LDI and PI (r = 0.132, p = 0.495). In reference to G-LDI, most patients in the non-MC group were classified as having alignment (72, 77.4%), while the MC group had an inhomogeneous composition (aligned: 34, 43.6%; hyperlordosis: 37, 47.4%). The agreement between the G-LDI and R-LDI was moderate (κ = 0.536, p < 0.001) to fair (κ = 0.383, p = 0.011) for patients with average or large PI, but poor (κ = -0.255, p = 0.245) for those with small PI. The areas under the curve for the G-LDI and R-LDI were 0.674 (95% CI, 0.592-0.757) and 0.745 (95% CI, 0.671-0.820), respectively. CONCLUSIONS: The R-LDI, which uses a PI-based proportional parameter, enables individual quantification of LL for all PI sizes and has been shown to have a higher accuracy in classifying cases and a stronger correlation with the risk of mechanical complications compared with G-LDI.

Anatomical feasibility for safe occipital condyle screw fixation.

PURPOSE: The occipital condyle (OC) screw can be a viable alternative option for the occipito-cervical fixation. However, the risk of vertebral artery (VA) injury during the direct OC screw fixation has not been adequately assessed. The purpose of this study was to establish the course of the VA (V3) relative to the nearby osseous structures to estimate the feasibility of OC screw fixation and describe its anatomical relationship depending on patient's age and sex. METHODS: A total of 387 three-dimensional computed tomographic angiograms (3D-CTA) were used and compared between two age groups. The vertebral artery diameter and two kinds of bony space were measured. The occipito-C1 arch space (O-C1S) and VA-occipital bone distance (VOD, six entry points) were measured on both sides. The feasibility of direct OC screw fixation can be represented by the VOD value; the minimum feasible value was determined to be 4 mm. Angular measurements (O-C1A and O-C2A) were also taken to assess their relationship to the bony space. RESULTS: The mean value of the O-C1S ranged from 9.0 to 9.9 mm. The mean value of the VOD ranged from 3.2 to 3.5 mm, and the proportion of individuals for which direct OC screw fixation was considered feasible ranged from 32 to 42 % in both age groups and there was no significant difference between two age groups. The VOD value was not affected by laterality or by gender (P > 0.05). The mean kyphosis of the O-C1A (-5° ± 5.2°, range -22° to 8°) was significantly smaller in the young age group compared to the older age group (-7.6° ± 5.3°, range -26° to 2°). The mean lordosis of the O-C2A (12.4° ± 6.4°, range 3°-33°) was significantly higher in the young age group compared to the older age group (10.4° ± 6.4°, range 0°-36°). CONCLUSIONS: The direct OC screw fixation was not possible in a considerable number of cases due to the limited space and the position of the VA regardless of age group. Only about one quarter (21-24 %) of all patients was affordable to place the direct OC screw bilaterally. There was more space available to place the direct OC screw when the angle of the upper cervical spine is more kyphotic.

Sequential alignment change of the cervical spine after anterior cervical discectomy and fusion in the lower cervical spine.

PURPOSE: The cervical spine has a linear chain of correlation or reciprocal relationship regionally (within the cervical spine) and globally (head to whole spine). The purpose of this study was to assess the sequential alignment change of the regional and global cervical spine after two-level anterior cervical discectomy and fusion (ACDF) performed on the lower cervical spine. METHODS: This study included 61 patients (mean age 56 ± 8.6 years; range 35-70 years) who underwent ACDF at C5-6-7 with a plate-cage construct and whose C-spine neutral lateral radiographs showed an identical degree of horizontal gaze (occipital slope) peri-operatively. We compared the change in cervical curvature from the occiput to C7 with the absolute value (slope angle) and relative value (between two different slopes). We also investigated the correlated change in multiple angular parameters according to the change in the occipital slope. RESULTS: The occipital slope was significantly correlated with the value of the C1-slope (r = 0.33) and C2- slope (r = 0.51). The value of the center of the sellar turcica-C7 sagittal vertical axis (St-SVA) was very closely related to the C1-slope (r = -0.83), C2-slope (r = -0.8), C2-7 angle (r = -0.43), and C2-5 angle (r = -0.46). The amount of angular change at the surgical level (C5-7A) was 5.8° (2.9° -> 8.5°), and the sum of the change in the C5-slope and C7-slope was 6° (3.1° + 2.9°). In general, the C2-5 angle decreased about 3°, in proportion to the upward inclination of C5-slope (3.1°), because the C2-slope was fixed. However, patients who showed improvement in cervical alignment (greatly increased C5-7 lordosis or greatly decreased St-SVA after surgery) often had upper cervical slope change (C1-s and C2-s). CONCLUSIONS: The ACDF procedure itself can induce regional slope change (C5-s and C7-s) directly at the surgical level and can also influence upper cervical slope change (C1-s and C2s) indirectly. Then the change in the upper cervical spine can induce a change in the St-CVA and spino-cranial angle (SCA).

Quantification of pediatric cervical spine growth at the cranio-vertebral junction.

OBJECTIVE: The purpose of this study was to investigate morphological change at the craniovertebral junction (CVJ) region using computed tomography. METHODS: A total of 238 patients were included in this study, and mean age was 47.8±21.3 months. Spinal canal diameter, Power's ratio, McRae line, antero-posterior C1 ring height, atlantoaxial joint space, C2 growth, epidural space from the dens (M-PB-C2) and longitudinal distance (basion to C2 lower margin, B-C2) were measured. The mean value of each parameter was assessed for individual age groups. The cohorts were then divided into three larger age groups : infancy (I) (≤2 years), very early (VE) childhood (2-5 years) and early (E) childhood (5≥ years). RESULTS: Spinal canal diameter increased with age; however, this value did not increase with statistical significance after VE age. A significant age-related difference was found for all C2 body and odontoid parameters (p<0.05). Mean McRae line was 8.5, 8, and 7.5 mm in the I, VE, and E groups, respectively. The M-PB-C2 line showed up-and-down dynamic change during early pediatric periods. CONCLUSION: Expansion of the spinal canal was restricted to the very early childhood period (less than 5 years) in the CVJ region; however, the C2 body and odontoid process increased continuously with age. The above results induced a dynamic change in the M-PB-C2 line. Although C2 longitudinal growth continued with age, the McRae line showed relatively little change.

Solitary cervical neurenteric cyst in an adolescent patient.

Spinal neurenteric cysts are uncommon congenital lesions, furthermore solitary neurenteric cysts of the upper cervical spine are very rare. A 15-year-old boy having an intraspinal neurenteric cyst located at cervical spine presented with symptoms of neck pain and both shoulders pain for 2 months. Cervical spine magnetic resonance (MR) imaging demonstrated an intradural extramedullary cystic mass at the C1-3 level without enhancement after gadolinium injection. There was no associated malformation on the MR imaging, computed tomography, and radiography. Hemilaminectomy at the C1-3 levels was performed and the lesion was completely removed through a posterior approach. Histological examination showed the cystic wall lined with ciliated pseudostratified columnar epithelium containing mucinous contents. Neurenteric cyst should be considered in the diagnosis of spinal solitary cystic mass.

Atypical Intramuscular Myxoma of the Lumbosacral Paraspinal Muscle: The First Case Report in Asian.

Intramuscular myxoma (IM) is a benign neoplasm of mesenchymal origin. We report a rare case of IM which was located in the lumbosacral paraspinal muscles. A 62-year-old female patient presented with progressive low back pain for 2 months, and the radiologic findings showed a large mass (4.0×3.5×6.5 cm) in the right lumbosacral paraspinal area. Total resection of the tumor was performed and the symptom was nearly resolved after surgery. Although the immuno-histopathological analysis was consistent with IM, there were some different findings from typical pathological characteristics of IM in this case. Firstly, the symptomatic change of the mass took relatively short time (less than 3 months), and this change was accompanied by partial calcification inside the mass. Moreover, iatrogenic interruption of paravertebral muscle by the other previous operation might be the promoting factor of the fibrous dysplasia, which can explain the pathogenesis of IM. To our knowledge, this is the eighth case of the lumbar paraspinal myxoma reported in the literatures and the first case in Asian population.