Spine
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Prospective, blinded validation study of an objective, quantitative measure to assess maximum canal compromise (MCC) and maximum spinal cord compression (MSCC) in individuals with acute cervical spinal cord injury (SCI). ⋯ Our results indicate that the intraobserver reliability for the MCC and MSCC was high. Although the interobserver reliability for all three radiologic parameters in the present study was below 0.75, the observed differences were small and largely accounted for by the limitations in the precision of the calibrated ruler. For cases with minimal cord compression, the measurement of canal stenosis (MCC) proved more accurate. In contrast, in cases with severe cord compression, the assessment of MSCC was more accurate. It is anticipated that the use of digital imaging technologies will further enhance the precision of these outcome measures.
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Comparative Study Clinical Trial
Comparison of the anatomical risk for vertebral artery injury associated with the C2-pedicle screw and atlantoaxial transarticular screw.
We evaluated the trajectories of atlantoaxial transarticular and C2-pedicle screws in 3 dimensions using computerized tomography. ⋯ C2-pedicle screw placement has nearly the same anatomic risk of vertebral artery injury as transarticular screw placement. Preoperative 3-dimensional evaluation may be useful for choosing the best surgical technique.
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Biomechanical laboratory research. ⋯ The 4 techniques equally restored strength and stiffness. No difference was seen in height restoration. Cement extrusion was significant in only 1 vertebral body, which may be attributable to the cement quantity.
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Comparative Study
The effects of rod contouring on spinal construct fatigue strength.
In vitro fatigue loading using a corpectomy model outfitted with posterior pedicle screw instrumentation. ⋯ Intraoperative rod contouring using a French Bender significantly reduces the fatigue life of titanium spinal constructs.
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An in vitro study on porcine spinal segments. ⋯ Repetitive shear loading can induce failure of porcine spinal segments, likely caused by fracture of the posterior elements, and, although repetitive anterior shear forces can also induce disc damage, this appears not to occur in intact segments, not even when flexed close to maximal.