To analyze the difference in sagittal balance based on different positions of both arms and to promote the proper lateral spine view which can reconstruct the most functional posture of sagittal balance.

We applied X-rays to thirty healthy male adults with no spinal diseases after application of marks on the skin surface at the location of the C7 and S1 vertebrae with the following five postures, standing lateral position with both arms neutral (posture A) with both shoulders flexed thirty degrees and ninety degrees (postures B and C) with both arms crossed (posture D) with both shoulders flexed ninety degrees and with both arms on a parallel bar (posture E). We analyzed the differences of the sagittal vertical axis, thoracic kyphotic angle, lumbar lordotic angle, and sacral inclination angle after the postural changes.

The average sagittal vertical axis value from posture A to E was 1.47±2.06 cm, -0.58±2.96 cm, -2.11±2.67 cm, 0.16±2.38 cm, and -0.51±2.70 cm. We discovered that five postures were statistically different (one-way ANOVA, p<0.001) and that posture D was the closest to posture A (Duncan's multiple comparison test). However we did not observe any statistical differences among the thoracic kyphotic angle, the lumbar lordotic angle, and sacral inclination angle postures.

We can reconstruct the functional sagittal alignment in the cross-arm position, which is the closest to the normal standing position.