Spine
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The biomechanical influence of in situ setting hydroxyapatite cement was examined for use in pedicle screw revision surgery. Pull-out testing of control and pedicle screws augmented with hydroxyapatite cement was performed in human cadaver vertebrae. ⋯ Hydroxyapatite cement may be a mechanically viable alternative to polymethyl methacrylate for augmenting revision pedicular instrumentation and should be considered for future experimental, animal, and clinical testing.
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Directions of the C1-C2 posterior transarticular screw trajectories making the longest path or violating the transverse foramen were measured by using an objective measuring method. ⋯ The areas on the superior articular surface of C2 intersected by the trajectories making the longest paths without violating the transverse foramen are clarified as a guide to the ideal and safe trajectories. The theoretical minimal risk and usual risk of the posterior C1-C2 transarticular screw fixation are presented as well.
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The dimensions and shapes of vertebral body endplates of inferior L4, inferior and superior L5, and superior S1 were analyzed. Computed tomographic scans parallel to each endplate were used to develop a standardized geometric model of the boundaries of each vertebral body. ⋯ Although the female endplates are smaller than their male counterparts, the overall shapes are similar.
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A retrospective cohort study of Michigan workers' compensation cases involving back injuries in 1986 and 1987 with incidence and outcome data. ⋯ The relative risk of compensable back injury is generally higher for females in white collar occupations, higher for males in blue collar occupations and approximately equal in service occupations. Although the risk of back injury is related to occupation, the same occupational factors do not operate as a barrier to return to work.
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Case Reports
Ossification of the ligamenta flava with severe myelopathy in a black patient. A case report.
A case of symptomatic ossification of ligamenta flava in a black man from Martinique (French West Indies) is reported. ⋯ Ossification of ligamenta flava may occur in black people. An incomplete postoperative recovery may be observed in such cases of unusual subacute compressive myelopathy.