Etiological Factors in the Pathogenesis of Femoral Trabecular Fatigue Fractures

Urovitz, E P; Fornasier, Victor; Risen, M. I.; Macnab, Ian

doi:10.1097/00003086-197709000-00040

Cited by 2 publications

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“…Urovitz et al 1977;Wenzel et al 1996;Mori et al 1997;Fazzalari et al 1998;Muir et al 1999;Vashishth et al 2000;Mashiba et al 2001) and in vitro (Fyhrie et al 1994;Keaveny et al 1994b;Wachtel et al 1997;Arthur Moore et al 2002). Evidence that damage serves as a remodeling stimulus (Burr et al 1985;Mori et al 1993;Bentolila et al 1998;Lee et al 2000;Li et al 2001;Martin 2002), decreases bone quality (Cooper 1993;Heaney 1993), and increases fracture susceptibility (Matheson et al 1987;Burr et al 1990;Tami et al 2003) motivates further study of what loading magnitudes induce damage in trabecular bone.…”

Section: Introductionmentioning

confidence: 99%

Damage in trabecular bone at small strains

Morgan¹,

Yeh²,

Keaveny³

2005

European Journal of Morphology

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Evidence that damage decreases bone quality, increases fracture susceptibility, and serves as a remodeling stimulus motivates further study of what loading magnitudes induce damage in trabecular bone. In particular, whether damage occurs at the smaller strains characteristic of habitual, as opposed to traumatic, loading is not known. The overall goal of this study was to characterize damage accumulation in trabecular bone at small strains (0.20 - 0.45% strain). A continuum damage mechanics approach was taken whereby damage was quantified by changes in modulus and residual strain. Human vertebral specimens (n = 7) were tested in compression using a multi-cycle load - unload protocol in which the maximum applied strain for each cycle, epsilonmax, was increased incrementally from epsilonmax = 0.20% on the first loading cycle to epsilonmax = 0.45% on the last cycle. Modulus and residual strain were measured for each cycle. Both changes in modulus and residual strains commenced at small strains, beginning as early as 0.24 and 0.20% strain, respectively. Strong correlations between changes in modulus and residual strains were observed (r = 0.51 - 0.98). Fully nonlinear, high-resolution finite element analyses indicated that even at small apparent strains, tissue-level strains were sufficiently high to cause local yielding. These results demonstrate that damage in trabecular bone occurs at apparent strains less than half the apparent compressive yield strain reported previously for human vertebral trabecular bone. Further, these findings imply that, as a consequence of the highly porous trabecular structure, tissue yielding can initiate at very low apparent strains and that this local failure has detectable and negative consequences on the apparent mechanical properties of trabecular bone.

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Section: Introductionmentioning

confidence: 99%

Damage in trabecular bone at small strains

Morgan¹,

Yeh²,

Keaveny³

2005

European Journal of Morphology

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Trabecular microfracture

Fazzalari

1993

Calcif Tissue Int

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Healing trabecular microfractures are a common feature in cancellous bone. These lesions, when observed in macerated cancellous bone slices, measure about 500 microns in diameter and surround fractures in trabeculae with microcallus. Whether microcallus is a structure acting primarily as a transient brace, preventing relative movement of the fragmented segments and enabling the trabecula to heal, or whether it is a permanent buttress reducing the stress on the fractured strut, preventing the healing process, is not known. Microfractures are the result of normal physical activity. Hence, the widespread occurrence of trabecular microfracture in cancellous bone implies that a reasonable rate of microfracture is physiologically tolerable. There are three putative effects for trabecular microfracture. One is that, in response to impulse loading, cancellous subchondral bone increases its rigidity due to osteosclerosis resulting from bone formed around microfractures. Another hypothesis is that, if sufficient trabecular microfractures occur, they will compromise the trabecular structure of the vertebra and the proximal femur leading to osteoporotic fracture. By inducing remodeling changes, microfractures have an effect on the maintenance of joint structure. There are two histological patterns for microfractures: an early stage, when actively forming woven bone is bridging the fracture; and a more common late stage, when woven bone is inactive. Femoral studies fail to demonstrate that an increasing number of healed or healing microfractures in osteoarthrosis causes the increase of bone in the head of femur. Only one study has reported a significant increase in the number of trabecular microfractures in osteoarthritic femoral heads compared with normal controls. This significant increase was in patients taking antiinflammatory drugs.(ABSTRACT TRUNCATED AT 250 WORDS)

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Etiological Factors in the Pathogenesis of Femoral Trabecular Fatigue Fractures

Cited by 2 publications

References 0 publications

Damage in trabecular bone at small strains

Damage in trabecular bone at small strains

Trabecular microfracture

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