Spine
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Case-control study. ⋯ 3.
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A retrospective case series. ⋯ 4.
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Retrospective review of the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database years 2010 to 2015. ⋯ 3.
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Retrospective analysis of collected data and operative experiment on human cadavers. ⋯ 3.
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Retrospective review of a prospectively collected multicenter database. ⋯ 2.