Spine
- 
    
    A retrospective study. ⋯ 4. 
- 
    
    A retrospective review. ⋯ 4. 
- 
    
    Retrospective cohort analysis. ⋯ 3. 
- 
    
    A systematic review. ⋯ 1. 
A retrospective study. ⋯ 4.
A retrospective review. ⋯ 4.
Retrospective cohort analysis. ⋯ 3.
A systematic review. ⋯ 1.