Fig. 4.

The drawings demonstrate the lumbar sagittal alignment which was altered by the change of PR-S1 angle (indicated by black arrows), high PR-S1 angle (a) and low PR-S1 angle (b). Gray line shows the lumbar alignment in average PR-S1. See text for the details. The PR-L2 (C and C#) remained unchanged. In high PR-S1 (a) PR-L5 (A) was higher than that of the average PR-S1 (A#). The lumbar spine was then flat. In low PR-S1 (b) PR-L5 (A) and PR-L4 (B) was less than those of the average PR-S1 (A# and B#, respectively). Lumbar lordosis was increased at lower lumbar segments and the lumbar spine appeared to move forward