Fig. 8.

Changes in intradiscal pressure recorded in the supra-adjacent motion segment. There were no significant changes in pressure in torsion or left and right bending. In extension, there was a significant decrease in pressure at T7–T8 after a two-level fusion was added from T9–T11 (*p < 0.001), which decreased again after the UIV (T8–T9) was instrumented with all three constructs tested (^# p < 0.001). In flexion there also was a decrease in pressure after adding a two-level fusion which increase above the intact levels after the topping off the fusion at T8–T9 (^† p < 0.001). Abbreviation: UIV, upper-instrumented vertebrae.