Tab. 1 (Fig. 2): Differences Δ of disk height (dh) and displacement (translation, tr) over time in dimensionless numbers:
For "dh" columns - 1: unfused cranial adjacent segment, 2: topmost (only fused segment in case of one-level fusion) fusion segment, 3: second fusion segment (in case of two-level fusion), 4: unfused caudal adjacent segment.
For "tr" columns - 1: cranial adjacent vertebra (upper vertebra of the cranial adjacent segment), 2: topmost fusion vertebra, 3: second fusion vertebra, 4: caudal adjacent vertebra (upper vertebra of the caudal adjacent segment).
Δdh pre = disc height postoperative - disc height preoperative = dh post - dh pre
Δdh post = disc height at follow-up - disc height postoperative = dh fu - dh post
Δdh fu = disc height at follow up - disc height preoperative = dh fu - dh pre
Δtr pre = displacement postoperative - displacement preoperative = tr post - tr pre
Δtr post = displacement at follow up - displacement postoperative = tr fu - tr post
Δtr fu = displacement at follow up - displacement preoperative = tr fu - tr pre