|کد مقاله||کد نشریه||سال انتشار||مقاله انگلیسی||ترجمه فارسی||نسخه تمام متن|
|5890049||1568155||2014||8 صفحه PDF||سفارش دهید||دانلود رایگان|
- Mechanical fatigue cycles of cortical bone beams were reduced by 3-year, high-dose alendronate treatment of female dogs.
- High-dose alendronate treatment resulted in 14% reduced osteon cross-sectional size.
- High- and low-dose treatments resulted in 20% reduction of osteocyte lacuna density.
Bisphosphonates are the most prescribed preventative treatment for osteoporosis. However, their long-term use has recently been associated with atypical fractures of cortical bone in patients who present with low-energy induced breaks of unclear pathophysiology. The effects of bisphosphonates on the mechanical properties of cortical bone have been exclusively studied under simple, monotonic, quasi-static loading. This study examined the cyclic fatigue properties of bisphosphonate-treated cortical bone at a level in which tissue damage initiates and is accumulated prior to frank fracture in low-energy situations. Physiologically relevant, dynamic, 4-point bending applied to beams (1.5Â mmÂ ÃÂ 0.5Â mmÂ ÃÂ 10Â mm) machined from dog rib (nÂ =Â 12/group) demonstrated mechanical failure and micro-architectural features that were dependent on drug dose (3 groups: 0, 0.2, 1.0Â mg/kg/day; alendronate [ALN] for 3Â years) with cortical bone tissue elastic modulus (initial cycles of loading) reduced by 21% (pÂ <Â 0.001) and fatigue life (number of cycles to failure) reduced in a stress-life approach by greater than 3-fold with ALN1.0 (pÂ <Â 0.05). While not affecting the number of osteons, ALN treatment reduced other features associated with bone remodeling, such as the size of osteons (âÂ 14%; ALN1.0: 10.5Â Â±Â 1.8, VEH: 12.2Â Â±Â 1.6, ÃÂ 103Â Î¼m2; pÂ <Â 0.01) and the density of osteocyte lacunae (âÂ 20%; ALN1.0: 11.4Â Â±Â 3.3, VEH: 14.3Â Â±Â 3.6, ÃÂ 102 #/mm2; pÂ <Â 0.05). Furthermore, the osteocyte lacunar density was directly proportional to initial elastic modulus when the groups were pooled (RÂ =Â 0.54, pÂ <Â 0.01). These findings suggest that the structural components normally contributing to healthy cortical bone tissue are altered by high-dose ALN treatment and contribute to reduced mechanical properties under cyclic loading conditions.
Journal: Bone - Volume 64, July 2014, Pages 57-64