Approximately 10% of the 250,000 hip fractures that occur each year in the United States and over 50% of the 500,000 age related spine fractures are thought to be spontaneous fractures associated with cyclic loading during the activities of daily living. Trabecular fatigue fractures are observed clinically as compressive stress fractures in the proximal femur, vertebrae, calcaneus and tibia. This study is aimed at predicting the compressive fatigue behavior of trabecular bone. We plan first to characterize the fatigue behavior of trabecular bone in compression by both mechanical testing and microscopy of fatigued specimens. Two hypothetical mechanisms for fatigue will be modelled: slow crack growth and creep. We hypothesize that slow crack growth will be the dominant mechanism of high cycle, low stress fatigue damage while creep will be the dominant mechanism of low cycle, high stress fatigue damage. The models we develop for these two mechanisms of fatigue should be capable of estimating the remaining fatigue life of trabecular bone of a given density and crack distribution at a given stress and temperature. Finally, the results of the models will be compared with the trabecular bone fatigue data to identify which mechanisms are responsible for fatigue. We expect these findings to improve our understanding of the relative importance of densitometric, morphological and loading factors in the etiology of spontaneous fractures of the hip and spine. Eventually, this improved understanding may lead to more successful approaches to the prevention of such age-related fractures in the elderly population most at risk.

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Research Project (R01)
Project #
5R01AR041894-03
Application #
2429583
Study Section
Oral Biology and Medicine Subcommittee 1 (OBM)
Project Start
1995-06-10
Project End
1999-05-31
Budget Start
1997-06-01
Budget End
1998-05-31
Support Year
3
Fiscal Year
1997
Total Cost
Indirect Cost
Name
Massachusetts Institute of Technology
Department
Engineering (All Types)
Type
Schools of Engineering
DUNS #
City
Cambridge
State
MA
Country
United States
Zip Code
02139
Moore, T L A; O'Brien, F J; Gibson, L J (2004) Creep does not contribute to fatigue in bovine trabecular bone. J Biomech Eng 126:321-9
Moore, Tara L; Gibson, Lorna J (2003) Fatigue microdamage in bovine trabecular bone. J Biomech Eng 125:769-76
Moore, Tara L; Gibson, Lorna J (2003) Fatigue of bovine trabecular bone. J Biomech Eng 125:761-8
Arthur Moore, T L; Gibson, L J (2002) Microdamage accumulation in bovine trabecular bone in uniaxial compression. J Biomech Eng 124:63-71
Makiyama, A M; Vajjhala, S; Gibson, L J (2002) Analysis of crack growth in a 3D Voronoi structure: a model for fatigue in low density trabecular bone. J Biomech Eng 124:512-20
Moore, T L; Gibson, L J (2001) Modeling modulus reduction in bovine trabecular bone damaged in compression. J Biomech Eng 123:613-22
Lee, T C; Arthur, T L; Gibson, L J et al. (2000) Sequential labelling of microdamage in bone using chelating agents. J Orthop Res 18:322-5
Vajjhala, S; Kraynik, A M; Gibson, L J (2000) A cellular solid model for modulus reduction due to resorption of trabeculae in bone. J Biomech Eng 122:511-5
Bowman, S M; Gibson, L J; Hayes, W C et al. (1999) Results from demineralized bone creep tests suggest that collagen is responsible for the creep behavior of bone. J Biomech Eng 121:253-8
Bowman, S M; Guo, X E; Cheng, D W et al. (1998) Creep contributes to the fatigue behavior of bovine trabecular bone. J Biomech Eng 120:647-54

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