Biomechanical and tomographic differences in the microarchitecture and strength of trabecular and cortical bone in the early stage of male osteoporosis.

Poh-Shiow Yeh,Weu Wang,Ruei-Ming Chen,Shing-Hwa Liu,Jaw-Lin Wang,Wei-Hui Chang,Yuan-Wen Lee

doi:10.1371/journal.pone.0219718

Abstract

Osteoporosis is a continuous process of loss of bone tissue. Compared to women, osteoporosis in men is associated with greater morbidity and mortality. In this study, we conducted tomographic and biomechanical evaluations of trabecular and cortical bone in the early stage of male osteoporosis. Male Wistar rats were subjected to orchiectomy and sham operation. Four weeks after being castrated, decreased levels of testosterone in plasma were found and resulted in concurrent bone loss. Separately, the orchiectomy led to significant tomographic alterations in the trabecular bone number, trabecular separation, and trabecular pattern factor. Data of a mechanistic compression test further showed that the orchiectomy diminished the maximum loading force, displacement at maximum load, energy at maximum load, and ultimate stress. Interestingly, orchiectomy-triggered changes in the maximum loading force and tomographic parameters were highly correlated. In contrast, tomographic and biomechanical analyses showed that 4 weeks after rats were orchiectomized, the thickness, area, maximum loading force, bone stiffness, energy at maximum load, and ultimate stress of the cortical bone were not changed. Taken together, this study showed specific differences in the microarchitecture and strength of trabecular bone in the early stage of male osteoporosis.

Highlights

Osteoporosis, a systemic aging skeletal disorder, is characterized by increased bone fragility and high risks of bone fracture [1, 2]
Biomechanical and tomographic differences in male osteoporosis internal (α’ and β’) diameters of the femur were measured by μCT in order to calculate the cross-sectional area (CSA) (C)
This study showed that 4 weeks after orchiectomy in male Wistar rats, levels of testosterone in plasma significantly decreased which concurrently prompted bone loss

Summary

Introduction

Osteoporosis, a systemic aging skeletal disorder, is characterized by increased bone fragility and high risks of bone fracture [1, 2]. Multiple risk factors are involved in the incidence of osteoporosis, including age, genetics, hormonal variations, smoking, and calcium and vitamin D deficiencies [4]. Osteoporosis was generally considered to be a woman’s disease, because men have larger skeletons, bone loss starts later and advances more slowly, and there was no period of rapid hormonal change [5, 6]. Osteoporosis in men exhibits different pathophysiological stages. Riggs et al showed that loss of cortical bone begins after the age of 75 years in men [8]. According to a statistical report by the National Osteoporosis Foundation, men experience 42% of total lifetime trabecular bone loss before the age of 50 years [5]. Osteoporosis in men and women has noteworthy variances in pathophysiology and clinical risks

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Discussion

Conclusion