- TDR had more physiologic motion profiles at the proximal adjacent level than fusions during flexion and extension.
- Results.Circumferential fusions exhibited significantly steeper motion gradients at the proximal adjacent level compared with TDR during flexion.
- Summary of Background Data.TDR has been shown to preserve motion and possibly prevent abnormal loading at the adjacent level.
- Between L3 and S1, the total range of motion accounted for by the L4/5 proximal adjacent level was 59% in 1-level fusions, 38% in 1-level TDR, and 29% in controls.
- Fusions, however, produced steeper motion gradients at the proximal adjacent level, while undergoing significantly greater sagittal plane translation during flexion-extension.
- A complete horizontal division of a building, constituting the area between two adjacent levels.