Spine
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Retrospective review of prospectively collected data. ⋯ 3.
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A retrospective study. ⋯ 3.
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In vitro experimental study. ⋯ N/A.
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A genetic association (replication) study. ⋯ 4.
Retrospective review of prospectively collected data. ⋯ 3.
A retrospective study. ⋯ 3.
In vitro experimental study. ⋯ N/A.
A genetic association (replication) study. ⋯ 4.