Spine
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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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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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Clinical Trial
The position of the aorta relative to the spine before and after anterior instrumentation in right thoracic scoliosis.
Preoperative magnetic resonance images (MRI) and postoperative axial computed tomography (CT) scans in 25 consecutive patients with idiopathic right thoracic adolescent scoliosis (AIS) and anterior correction and fusion with a dual rod system were analyzed in a prospective study. ⋯ This MRI and CT based study of 25 patients with thoracic AIS treated by standard open dual rod and dual screw instrumentation demonstrates a migration of the aorta by 31 degrees from a more posterolateral position before surgery to a more anteromedial position after surgery at the curve apex. Scoliosis surgeons should be aware of these changes; any excessive contralateral screw penetration must be avoided at any level.
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A longitudinal follow-up of Modic changes on magnetic resonance imaging (MRI). ⋯ Modic changes are common MRI findings in patients with degenerative lumbar disc disease. We found evidence that Modic Type II changes may be less stable than previously assumed.
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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.