Spine
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Retrospective study. ⋯ 3.
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Empirical cross-sectional multicenter study. ⋯ 4.
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Retrospective study. ⋯ 4.
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Secondary analysis of data from a double-blind randomized controlled trial. ⋯ 2.
Retrospective study. ⋯ 3.
Empirical cross-sectional multicenter study. ⋯ 4.
Retrospective study. ⋯ 4.
Secondary analysis of data from a double-blind randomized controlled trial. ⋯ 2.