Spine
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Comparative Study
Cervical spine motion generated with manual versus jackson table turning methods in a cadaveric c1-c2 global instability model.
STUDY DESIGN.: Cadaveric biomechanical study. OBJECTIVE.: To quantify spinal motion created by transfer methods from supine to prone position in a cadaveric C1-C2 global instability model. SUMMARY OF BACKGROUND DATA.: Patients who have sustained a spinal cord injury remain at high risk for further secondary injury until their spine is adequately stabilized. ⋯ There was minimal difference in C1-C2 motion generated when comparing all 3 head holding devices. CONCLUSION.: The data demonstrate that manual log-roll technique generated significantly more C1-C2 motion compared to the Jackson table technique. Choice of headrest has a minimal effect on the amount of motion generated during patient transfer, except that the Mayfield device demonstrates a slight trend toward increased C1-C2 motion.
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STUDY DESIGN.: Biomechanical study of vertebroplasty in cadaver motion segments. OBJECTIVES.: To determine how the volume of injected cement influences: (a) stress distributions on fractured and adjacent vertebral bodies, (b) load-sharing between the vertebral bodies and neural arch, and (c) cement leakage. SUMMARY OF BACKGROUND DATA.: Vertebroplasty is increasingly used to treat vertebral fractures, but there are problems concerning adjacent level fracture and cement leakage, both of which may depend on the volume of injected cement. ⋯ Following VP2, increases in IDP and compressive stiffness were proportional to percentage fill. CONCLUSION.: About 3.5 cm of PMMA largely restored normal stress distributions to fractured and adjacent vertebral bodies, but 7 cm were required to restore motion segment stiffness and load-sharing between the vertebral bodies and neural arch. Cement leakage, IDP and compressive stiffness all increased with percentage fill.
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STUDY DESIGN.: An in vitro study on human multilevel spinal segments. OBJECTIVE.: To determine the differences in biomechanical characteristics between 4 separate regions of the human spine and to provide quantitative information is derived on the range of motion (ROM), neutral zone (NZ), neutral zone stiffness (NZstiff), and flexibility (FLEX). SUMMARY OF BACKGROUND DATA.: Limited literature is available about the biomechanical behavior of different regions of the human spine, in particular with multilevel segments. ⋯ Flexibility of the spinal regions was variable; no significant differences were found between the 4 spinal regions. CONCLUSION.: This study showed the differences in ROM, NZ, and NZ stiffness between thoracolumbar regions of the human spine in axial rotation, flexion/extension, and lateral bending. Separate multilevel spinal segments were tested in 1 study, and therefore characteristics of different regions are truly comparable.
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STUDY DESIGN.: To examine the distribution of apoptotic cells and expression of tumor necrosis factor (TNF)-alpha and its receptors in the spinal hyperostotic mouse (twy/twy) with chronic cord compression using immunohistochemical methods. OBJECTIVE.: To study the mechanisms of apoptosis, particularly in oligodendrocytes, which could contribute to degenerative change and demyelination in chronic mechanical cord compression. SUMMARY OF BACKGROUND DATA.: TNF-alpha acts as an external signal initiating apoptosis in neurons and oligodendrocytes after spinal cord injury. ⋯ Immunoblot analysis demonstrated overexpression of TNF-alpha, TNFR1, and TNFR2 in severe compression. The expression of TNF-alpha appeared in local cells including microglia while that of TNFR1 and TNFR2 was noted in apoptotic oligodendrocytes. CONCLUSION.: Our results suggested that the proportion of apoptotic oligodendrocytes, causing spongy axonal degeneration and demyelination, correlated with the magnitude of cord compression and that overexpression of TNF-alpha, TNFR1, and TNFR2 seems to participate in apoptosis of such cells in the chronically compressed spinal cord.
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STUDY DESIGN.: A case report. OBJECTIVES.: To report a case of progressive kyphoscoliosis associated with a tethered cord that was corrected by posterior vertebral column resection after complicated untethering surgery. SUMMARY OF BACKGROUND DATA.: There have been few clinical reports on posterior vertebral column resection conducted for severe deformity associated with a tethered cord. ⋯ RESULTS.: Good correction of kyphoscoliosis was obtained without further neurologic deterioration. The Cobb angles of scoliosis was 103 degrees before surgery and 25 degrees after surgery (correction rate; 75.7%), and that of kyphosis was 90 degrees and 36 degrees , respectively (correction rate; 60.0%). CONCLUSION.: Correction of progressive kyphoscoliosis associated with a tethered cord can be achieved successfully by posterior vertebral column resection even after complicated untethering surgery.