2004 Fiscal Year Final Research Report Summary
Effects of degee of mineralization in bone on mechanical property of bone
| Project/Area Number |
15591583
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Orthopaedic surgery
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| Research Institution | Kagawa University Faculty of Medicine |
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Principal Investigator |
MASHIBA Tasuku Kagawa University, Dept.Of Orthopedic Surgery, Faculty of Medicine, Senior assistant professor, 医学部, 講師 (40335857)
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| Co-Investigator(Kenkyū-buntansha) |
MORI Satoshi Kagawa University, Dept.Of Orthopedic Surgery, Faculty of Medicine, Associate professor, 医学部, 助教授 (00190992)
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| Project Period (FY) |
2003 – 2004
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| Keywords | bone remodeling / bisphosphonate / degree of mineralization / osteon |
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| Research Abstract |
We evaluated the effects of suppressed bone remodeling caused by bisphosphonate on microdamage accumulation and degree of mineralization of bone (DMB) for the dog rib in two independent studies. (Study1) Thirty-six female beagles, 1-2 years old, were treated daily for one year with saline vehicle, risedronate at 0.5 mg/kg/day or alendronate at 1.0 mg/kg/day. (Study2) Twenty-nine beagles, 1 year old, were given lactose, incadronate at 0.3 mg/kg/day or 0.6 mg/kg/day for three years. In both studies, 9^<th> rib was harvested. Intracortical remodeling was significantly suppressed following either one year or three years bisphosphonate treatment without impairment of primary mineralization although remodeling rate were obviously lower in study2 than in study1 due to the aging of animals. Microdamage accumulation was significantly increased following any bisphosphonate treatment in response to the extent of remodeling suppression. One year treatment with risedronate or alendronate did not significantly affect on the mean DMB or osteonal distribution based on DMB. In contrast, mean DMB was significantly increased following three years incadronate treatments, and osteonal distributions based on DMB showed a dose-dependent shift towards the higher values in incadronate treated animals when compared with controls. Our results demonstrated that DMB was increased following only three years but not one year bisphosphonate treatment. This suggests that suppressed remodeling induced by long term bisphosphonate treatment increased DMB by increasing the population of old, highly mineralized osteons, however, the expression of this phenomenon depends on duration of the treatment because the secondary mineralization is very slow process.
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