Spine
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Retrospective database study. ⋯ 3.
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Retrospective analysis. ⋯ 4.
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Retrospective cohort study. ⋯ 3.
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Retrospective case control study. ⋯ 3.
Retrospective database study. ⋯ 3.
Retrospective analysis. ⋯ 4.
Retrospective cohort study. ⋯ 3.
Retrospective case control study. ⋯ 3.