Spine
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    Prospective subcohort study. ⋯ 2. 
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    Observational StudyCervical spine clearance protocols in level 1 trauma centers in the United States.Observational, cross-sectional. ⋯ 4. 
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    Comparative StudyRisk factors of adjacent segment disease requiring surgery after lumbar spinal fusion: comparison of posterior lumbar interbody fusion and posterolateral fusion.A retrospective study. ⋯ 3.