**5. Conclusions**

The majority of patients with osteoporosis had spinal sagittal malalignment, and more than 70% of patients without VFs, had spinal sagittal malalignment. Furthermore, patients with spinal sagittal malalignment had worse LBP and HRQoL compared with patients with normal spinal sagittal alignment. These findings sugges<sup>t</sup> that spinal sagittal malalignment is a potential risk factor for LBP and HRQoL in patients with osteoporosis.

**Author Contributions:** T.M. and M.M. revised the manuscript and participated in the formulation of the study design. T.N. drafted the manuscript and collected clinical data. K.M., A.K. (Ayumu Kawakubo), H.F., T.K., A.K. (Akiyoshi Kuroda), Y.Y., Y.M. and Y.N. collected clinical data, and E.S., W.S., T.I., K.I., T.A. and S.O. helped to revise the manuscript. K.U. carried out statistical analyses, and M.T. and G.I. conceived the study, participated in the formulation of its design and coordinated the work. T.M. and M.M. equally contributed in this study. All authors have read and agreed to the published version of the manuscript.

**Funding:** This investigation was supported in part by JOA-Subsidized Science Project Research 2018-2.

**Institutional Review Board Statement:** The study was conducted according to the guidelines of the Declaration of Helsinki, and approved by Institutional Review Board in Kitasato University (Approval code, #B17–197).

**Informed Consent Statement:** Informed consent was obtained from all subjects involved in the study.

**Data Availability Statement:** The data presented in this study are available on request from the corresponding author.

**Acknowledgments:** We thank Motoki Makabe, Yukie Arai, Kazue Takakura and Ikumi Sekihara for their assistance with this study. M.M., Y.A., K.T. and I.S. have agreed to the published version of the manuscript.

**Conflicts of Interest:** The authors declare that there is no conflict of interest.
