Journal of neurosurgery. Spine
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OBJECT Safe and effective insertion of occipital bone screws requires morphological analysis of the occipital bone, which is poorly documented in the literature. The authors of this study present morphological data for determining the area of screw placement for optimal internal fixation. METHODS The subjects of this institutional review board-approved retrospective study were 105 individuals without head and neck disease who underwent CT imaging at the authors' hospital. ⋯ At positions more than 2 cm laterally, the ratio was < 15%, and the ratio gradually decreased further laterally. CONCLUSIONS Screws that are 8 mm long can be placed in the area extending 2 cm laterally from the EOP at the level of the superior nuchal line and approximately 3 cm inferior to the center. These results suggest that it may be possible to effectively insert a screw over a wider area than the conventional reference range.
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OBJECT Usually additional anchors into the ilium are necessary in long fusion to the sacrum for degenerative lumbar spine disorders (DLSDs), especially for adult spine deformity. Although the use of anchors is becoming quite common, surgeons must always keep in mind that the sacroiliac (SI) joint is mobile and they should be aware of the kinematic properties of the SI joint in patients with DLSDs, including adult spinal deformity. No previous study has clarified in vivo kinematic changes in the SI joint with respect to patient age, sex, or parturition status or the presence of DLSDs. ⋯ SI joint motion was significantly negatively correlated with the cross-sectional area of the trunk muscles during both flexion and extension of the trunk. CONCLUSIONS The authors elucidated the mobility and kinematic characteristics of the SI joint in patients with DLSDs compared with healthy volunteers for the first time. This information is useful for spine surgeons because of the recent increase in spinopelvic fusion for the treatment of DLSDs.
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OBJECT The authors evaluated the biomechanical effects of an interspinous process (ISP) device on kinematics and load sharing at the implanted and adjacent segments. METHODS A 3D finite-element (FE) model of the lumbar spine (L1-5) was developed and validated through comparison with published in vitro study data. Specifically, validation was achieved by a flexible (load-control) approach in 3 main planes under a pure moment of 10 Nm and a compressive follower load of 400 N. ⋯ Further, the stress at the bone-implant interface increased significantly. The influence of the ISP device on load sharing parameters in motion directions other than extension was negligible. CONCLUSIONS Although ISP devices apply a distraction force on the processes and prevent further extension of the index segment, their implantation may cause changes in biomechanical parameters such as facet load, intradiscal pressure, and range of motion at adjacent levels in extension.
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OBJECT Regional cervical sagittal alignment (C2-7 sagittal vertical axis [SVA]) has been shown to correlate with health-related quality of life (HRQOL). The study objective was to examine the relationship between cervical and thoracolumbar alignment parameters with HRQOL among patients with operative and nonoperative adult thoracolumbar deformity. METHODS This is a multicenter prospective data collection of consecutive patients with adult thoracolumbar spinal deformity. ⋯ This effect may be direct or a reciprocal effect of the underlying global deformities on regional cervical alignment. However, the partial correlation analysis, controlling for the magnitude of the thoracolumbar deformity, suggests that there is a direct effect of cervical alignment on health measures. Improvements in regional cervical alignment postoperatively correlated positively with improved HRQOL.
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Comparative Study
Posterior thoracic corpectomy with cage reconstruction for metastatic spinal tumors: comparing the mini-open approach to the open approach.
OBJECT Spinal metastases most commonly affect the vertebral bodies of the spinal column, and spinal cord compression is an indication for surgery. Commonly, an open posterior approach is employed to perform a transpedicular costotransversectomy or lateral extracavitary corpectomy. Because of the short life expectancies in patients with metastatic spinal disease, decreasing the morbidity of surgical treatment and recovery time is critical. ⋯ The open approach had a higher overall infection rate of 17.9% compared with that in the mini-open approach of 9.5%, but this was not statistically significant (p = 0.409). CONCLUSIONS The mini-open transpedicular corpectomy is associated with less blood loss and shorter hospital stay compared with open transpedicular corpectomy. The mini-open corpectomy also trended toward lower infection and complication rates, but these did not reach statistical significance.