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

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.

Physiological testosterone replacement effects on male aged rats with orchiectomy-induced osteoporosis in advanced stage: a tomographic and biomechanical pilot study

“…The current study showed that long-term orchiectomy promoted a complete testosterone depletion, culminating in remarkable alterations in the bone remodeling process with a significant deterioration of the trabecular bone, thus proving to be sufficient to cause osteoporosis induced by hormone depletion. In general, the findings provided by mCT (microcomputed tomography) analysis are in accordance with the literature, which shows that the trabecular bone is the most affected in osteoporosis [19,27]. Considerable differences in cortical bone volume could be found in longer periods, according to previous studies reporting that orchiectomy significantly affects the cortical bone mass in only 4 months [28,29].…”

“…The available evidence regarding the testosterone role in bone health has been described in different methods, and despite the fact that the results demonstrate that the hormone absence is related to a decrease in the bone quality, the information reporting the effect of testosterone therapy on the improvement of bone parameters are still scarce [13][14][15][16][17][18][19]. In our study, we evaluated the effect of physiological testosterone replacement on male aged rats with advanced stage of osteoporosis induced by physical castration.…”

“…The phantom rods were scanned and reconstructed using the same parameters as those used for the femur, as described above. The attenuation coefficient was entered into the calibration dialogue window in CTAn to determine BMD (mg/cm 3 ) [19,20,22].…”

“…Therefore, it seems plausible to correlate low bioavailable testosterone levels in aging men with loss in mineral bone density (BMD), bone volume and increased fracture risk, similar to women in menopause. The clinical or in vivo literature regarding low bioavailable testosterone and hormonal replacement in correlation with bone loss and increased risk of fracture in men is still limited [13][14][15][16][17][18][19]. Although there are some clinical trials showing an improvement of BMD by testosterone replacement treatment, Lee et al [15] described that most studies evaluating testosterone replacement in hypogonadal men have been uncontrolled, performed in a short term and involving a small sample size with a variety of causes for their hypogonadism.…”

Deciphering the Relevance of Bone ECM Signaling

“…Moreover, in male Wistar rats subjected to orchiectomy bone loss is observed too. Separately, the orchiectomy led to significant tomographic alterations in the trabecular bone number, trabecular separation, and trabecular pattern factor [134]. The same results have been reported in early osteoporosis patients, since the bone loss is mainly a trabecular deficiency, and a decrease of all these characteristics is observed [29].…”