Spine
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Comparative Study
Radiographic assessment of segmental motion at the atlantoaxial junction in the Klippel-Feil patient.
A retrospective review of 33 consecutive Klippel-Feil syndrome (KFS) patients at a single institution. ⋯ Hypermobility of the atlantoaxial junction, as indicated by increased AADI on flexion-extension radiographs, is not necessarily associated with an increased risk for the development of symptoms or neurologic signs in the KFS patient. Occipitalization plays an integral role in the degree of motion at the atlantoaxial region. Greatest AADI values were in patients with occipitalization and a fused C2-C3 segment. The presence of symptoms was not related to the degree of AADI change. Evaluation of the PADI provides additional information for identifying patients at risk for developing symptoms. Nonetheless, KFS patients remain largely asymptomatic.
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A C1-C2 operation by the transoral approach was simulated to study the anatomic stratification, various structures, and adjacent relationships. The anatomic parameters in relation to transoral atlantoaxial reduction plate (TARP) internal fixation were measured. ⋯ An atlantoaxial surgery through transoral approach is safe and feasible. This approach is suitable for an anterior TARP internal fixation, and the design of the internal fixation system should be based on the above anatomic data.
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Comparative Study
Fluoroscopically assisted surgical treatments of spinal disorders: conceptus radiation doses and risks.
A series of anterior-posterior and lateral fluoroscopic exposures at 5 spinal levels were performed on anthropomorphic phantoms simulating the 3 trimesters of gestation. ⋯ Individual dose assessment is paramount in every pregnancy. Variations in fluoroscopy practices and gestational stage significantly affect fetal doses.
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Comparative Study
Mechanical stiffness of segmental versus nonsegmental pedicle screw constructs: the effect of cross-links.
A biomechanical study in porcine spines of the construct stiffness effects of segmental pedicle screws. Stiffness effects of supplementation of nonsegmental screw constructs with cross-links was also evaluated. ⋯ Segmental pedicle screw constructs increased mechanical stiffness compared to nonsegmental constructs in our fusion models. Placement of a single cross-link with nonsegmental screws eliminated statistical differences for 3 and 4-vertebral level constructs, and may be a satisfactory alternative in this clinical setting. Caution in applying these results inlonger constructs is recommended, given persistent increased stiffness found for the segmental 5-vertebral level models.
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Comparative Study
Kinematics of the cervical spine in lateral bending: in vivo three-dimensional analysis.
Kinematics of the cervical spine during lateral bending were investigated using a novel system of three-dimensional motion analysis. ⋯ We succeeded in identifying in vivo coupled motions of the cervical spine in lateral bending for the first time.