Spine
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This static, nondestructive, in vitro biomechanical study examines anterior solid rod construct stiffness following the addition of multilevel, threaded cortical bone dowels in a bovine model. A comparison is made with a clinically relevant posterior construct with and without an anterior release. ⋯ Disc space augmentation increased stiffness except in axial rotation, in which values were restored to the intact level. Stiffness was superior to a clinically relevant posterior instrumentation comparison group following anterior release, and was equivalent to a posterior construct without anterior release except in anterior flexion. In addition, the implants enhanced lordosis. Increased rigidity should improve rates of arthrodesis, while maintenance of sagittal alignment may prevent pathologic compensatory curves in adjacent spinal segments. Further research is required to determine the optimal method of achieving structural interspace support.
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A prospective analysis of the relative influence of pain-specific and performance-specific cognitive variables on lifting tasks using empirically derived measures. ⋯ Data suggest that what patients believed they could achieve accurately determined their actual spinal function, independent of their sense of control over pain or their distress. Approaches to low back disorders emphasizing perceived pain control as a central cognitive determinant of disability were unsupported.
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An analysis of the vascular anatomy relative to the underlying discs in the lower lumbar spine performed by using radiologic studies. ⋯ The results of this study suggest that a laparoscopic approach to the L3-L4 intervertebral disc will seldom be accomplished without significant retraction of the aorta. Access to the L4-L5 space will be accomplished readily in approximately one third of the patients. In the others, it will require significant vascular dissection. The L5-S1 space, conversely, will be readily accessible by the authors' definitions without significant vessel dissection in the majority of patients.
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Three cases of a previously undescribed body fracture of the axis vertebra are presented. ⋯ The presumed mechanism of injury in the described fracture is one of asymmetrical axial compression. The fracture can be managed safely in a halo jacket.