Effect of ibandronate on bending strength and toughness of rodent cortical bone: Possible implications for fracture prevention

Biomechanical Properties of Metastatically Involved Osteolytic Bone

PURPOSE OF REVIEW

Skeletal metastasis involves the uncoupling of physiologic bone remodeling resulting in abnormal bone turnover and radical changes in bony architecture, density, and quality. Bone strength assessment and fracture risk prediction are critical in clinical treatment decision-making. This review focuses on bone tissue and structural mechanisms altered by osteolytic metastasis and the resulting changes to its material and mechanical behavior.

RECENT FINDINGS

Both organic and mineral phases of bone tissue are altered by osteolytic metastatic disease, with diminished bone quality evident at multiple length-scales. The mechanical performance of bone with osteolytic lesions is influenced by a combination of tissue-level and structural changes. This review considers the effects of osteolytic metastasis on bone biomechanics demonstrating its negative impact at tissue and structural levels. Future studies need to assess the cumulative impact of cancer treatments on metastatically involved bone quality, and its utility in directing multimodal treatment planning.

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

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.

Main differences in osteoporotic fracture models: which should I use?

Osteoporosis is a global public health problem currently affecting more than 200 million people worldwide. Major research efforts are being made to improve the outcomes for patients with osteoporosis. However, the treatment of fractures associated with osteoporosis remains unsatisfactory. Animal models continue to be an important tool for establishing strategies to treat osteoporotic fractures, and various methods of inducing osteoporosis have been used. Investigators must select a model that best reflects the clinical problem being studied, and the underlying pathophysiology of the osteoporosis in the target patient group. In particular a model for Type I post-menopausal osteoporosis should mimic a fall in oestrogen and rise in osteoclast activity observed with this condition, whereas a model for type II 'senile' osteoporosis should mimic the fall in osteoblast activity. Unfortunately, there is no single all-encompassing model that precisely imitates the underlying osteoporosis or the fracture patterns seen in humans. As such the choice of species and model must be individualised to the scientific question being addressed. This article summarises general considerations when choosing an osteoporotic fracture model and outlines existing models of osteoporosis. The most appropriate model in a range of osteoporotic fracture research scenarios are subsequently considered.