Differences in the effects of BMI on bone microstructure between loaded and unloaded bones assessed by HR-pQCT in Japanese postmenopausal women

Norifumi Fujii; Manabu Tsukamoto; Nobukazu Okimoto; Miyuki Mori; Yoshiaki Ikejiri; Toru Yoshioka; Makoto Kawasaki; Nobuhiro Kito; Junya Ozawa; Ryoichi Nakamura; Shogo Takano; Saeko Fujiwara

doi:10.1016/j.afos.2021.05.002

Differences in the effects of BMI on bone microstructure between loaded and unloaded bones assessed by HR-pQCT in Japanese postmenopausal women

Osteoporos Sarcopenia. 2021 Jun;7(2):54-62. doi: 10.1016/j.afos.2021.05.002. Epub 2021 May 26.

Authors

Norifumi Fujii^{1

2}, Manabu Tsukamoto³, Nobukazu Okimoto^{4

5}, Miyuki Mori⁶, Yoshiaki Ikejiri⁵, Toru Yoshioka⁵, Makoto Kawasaki³, Nobuhiro Kito⁷, Junya Ozawa⁷, Ryoichi Nakamura¹, Shogo Takano¹, Saeko Fujiwara⁸

Affiliations

¹ Department of Rehabilitation, Shimura Hospital, Hiroshima, Japan.
² Hiroshima International University Major in Medical Engineering and Technology Graduate School of Medical Technology and Health Welfare Sciences, Hiroshima, Japan.
³ Department of Orthopedic Surgery, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan.
⁴ Okimoto Clinic, Hiroshima, Japan.
⁵ Department of Orthopedic Surgery, Shimura Hospital, Hiroshima, Japan.
⁶ Department of Radiology, Shimura Hospital, Hiroshima, Japan.
⁷ Department of Rehabilitation, Hiroshima International University, Hiroshima, Japan.
⁸ Department of Pharmacy, Yasuda Women's University, Hiroshima, Japan.

Abstract

Objectives: The relationship between weight-related load and bone mineral density (BMD)/bone microstructure under normal load conditions using high-resolution peripheral quantitative computed tomography (HR-pQCT) remains unconfirmed. The study aims to investigate the differences in effect of body mass index (BMI) on BMD/bone microstructure of loaded and unloaded bones, respectively, in Japanese postmenopausal women.

Methods: Fifty-seven postmenopausal women underwent HR-pQCT on the tibia and radius. Correlation analysis, principal component (PC) analysis, and hierarchical multiple regression were performed to examine the relationship between BMI and HR-pQCT parameters.

Results: Several microstructural parameters of the tibia and radius correlated with BMI through a simple correlation analysis, and these relationships remained unchanged even with an age-adjusted partial correlation analysis. PC analysis was conducted using seven bone microstructure parameters. The first PC (PC1) reflected all parameters of trabecular and cortical bone microstructures, except for cortical porosity, whereas the second PC (PC2) reflected only cortical bone microstructure. Hierarchical multiple regression analysis indicated that BMI was more strongly related to BMD/bone microstructure in the tibia than in the radius. Furthermore, BMI was associated with trabecular/cortical BMD, and PC1 (not PC2) of the tibia and radius. Thus, BMI was strongly related to the trabecular bone microstructure rather than the cortical bone microstructure.

Conclusions: Our data confirmed that BMI is associated with volumetric BMD and trabecular bone microstructure parameters in the tibia and radius. However, although BMI may be more related to HR-pQCT parameters in the tibia than in the radius, the magnitude of association is modest.

Keywords: Body mass index; Bone mineral density; High-resolution peripheral quantitative computed tomography; Loaded bone; Osteoporosis.