Effects of High Bone Turnover on the Biomechanical Properties of the L3 Vertebra in an Ovine Model of Early Stage Osteoporosis

Kennedy, Oran D.; Brennan, Orlaith; Mahony, Nicholas; Rackard, Susan M.; O’Brien, Fergal J.; Taylor, David; Lee, Clive T.

doi:10.1097/brs.0b013e318186b292

Cited by 19 publications

(10 citation statements)

References 29 publications

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“…In line with international literature ovariectomy alone had only minor effects on bone mass and structure . However, effects on the cortical bone reach level of significance 12 months after OVX comparable to results published recently by other groups .…”

Section: Discussionsupporting

confidence: 90%

Sheep model for osteoporosis: Sustainability and biomechanical relevance of low turnover osteoporosis induced by hypothalamic–pituitary disconnection

Oheim

Beil

Köhne

et al. 2013

Journal Orthopaedic Research

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Hypothalamo-pituitary disconnection (HPD) leads to low bone turnover and osteoporosis in sheep. To determine the sustainability of bone loss and its biomechanical relevance, we studied HPD-sheep 24 months after surgery (HPD þ OVX-24) in comparison to untreated control (Control), ovariectomized sheep (OVX), and sheep 12 months after HPD (HPD þ OVX-12). We performed histomorphometric, HR-pQCT, and qBEI analyses, as well as biomechanical testing of all ewes studied. Twenty-four months after HPD, histomorphometric analyses of the iliac crest showed a significant reduction of BV/TV by 60% in comparison to Control. Cortical thickness of the femora measured by HR-pQCT did not change between 12 and 24 months after HPD but remained decreased by 30%. These structural changes were caused by a persisting depression of osteoblast and osteoclast cellular activity. Biomechanical testing of the femora showed a significant reduction of bending strength, whereas calcium content and distribution was found to be unchanged. In conclusion, HPD surgery leads to a persisting low turnover status with negative turnover balance in sheep followed by dramatic cortical and trabecular bone loss with consequent biomechanical impairment. #

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Section: Discussionsupporting

confidence: 90%

Sheep model for osteoporosis: Sustainability and biomechanical relevance of low turnover osteoporosis induced by hypothalamic–pituitary disconnection

Oheim

Beil

Köhne

et al. 2013

Journal Orthopaedic Research

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“…Comparison between the two groups found that the modulus was less in the OVX group than in the control group at all three locations. This is consistent with previous work on these animals where we showed using a series of fluorochrome dyes, that following ovariectomy there was a significant increase in trabecular bone turnover (Kennedy et al, 2008).…”

Section: Discussionsupporting

confidence: 82%

Biomechanical properties across trabeculae from the proximal femur of normal and ovariectomised sheep

Brennan

Kennedy

Lee

et al. 2009

Journal of Biomechanics

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“…We have previously demonstrated an increase compact bone turnover and porosity in an ovine model of osteoporosis during the initial 12‐months postovariectomy without adversely affecting biomechanical properties 5. Conversely, we have also demonstrated a significant reduction in the biomechanical properties of trabecular bone associated with increased turnover 9. Here we examine the effect of estrogen deficiency on compact bone geometry, intracortical remodeling, porosity, and biomechanical parameters in an ovine model of osteoporosis over a 31‐month period.…”

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confidence: 85%

Structural adaptation and intracortical bone turnover in an ovine model of osteoporosis

Healy

Kennedy

Brennan

et al. 2009

Journal Orthopaedic Research

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Compact bone makes up approximately 80% of the human skeletal mass. This study examines the effect of estrogen deficiency on compact bone turnover and associated geometrical structural adaptation over a 31-month period in a large animal model. Twenty-seven skeletally mature sheep were divided into control (n ¼ 16) and ovariectomy group (OVX, n ¼ 11). Animals were administered five different fluorochrome dyes to label intracortical bone turnover, and sacrificed at 31 months. Compact bone samples were analyzed for cortical geometry, intracortical turnover at five time points, resorption cavities, porosity, and compressive strength. Intracortical bone turnover was significantly increased in OVX, which demonstrated seasonal variation. Cross-sectional area in OVX was significantly greater than control and was associated with an increased section modulus. Intracortical porosity was significantly increased in OVX, however, there was no significant difference in ultimate compressive strength between the groups. Our results demonstrate increased intracortical bone turnover, resportion spaces, and porosity in OVX, without adversely affecting compressive strength. Our results also support the hypothesis of geometrical adaptation of compact bone in response to estrogen deficiency. These results suggest an early structural compensatory response in compact bone, despite increased intracortical turnover. Keywords: compact bone; estrogen; ovine; bone turnover; bone geometry Bone strength depends not only on material properties, but also on structural properties. The structural properties of bone depend on size and shape, as well as its microarchitecture.1 Adding mass away from the center of the bone, periosteal apposition, can dramatically affect a bone's ability to resist bending and torsion. It has been estimated that an increase of 10% in periosteal diameter would lead to a 50% increase in axial compressive strength and a 70% increase in bending strength.2 These parameters are important considerations in the pathophysiology of skeletal diseases such as osteoporosis and fracture.In this study, we used an ovariectomy sheep model to study the effects of estrogen deficiency on compact bone over a 31-month period. The sheep has been used previously as an animal model for studying bone turnover, porosity, and biomechanical aspects of osteoporosis. [3][4][5] Similarities between the hormone profiles of ewes and women, a comparable metabolic rate, and commensurate bone remodeling cycles support the use of the ovine model of postmenopausal osteoporosis. [6][7][8] We have previously demonstrated an increase compact bone turnover and porosity in an ovine model of osteoporosis during the initial 12-months postovariectomy without adversely affecting biomechanical properties.5 Conversely, we have also demonstrated a significant reduction in the biomechanical properties of trabecular bone associated with increased turnover. 9 Here we examine the effect of estrogen deficiency on compact bone geometry, intracortical remodeling, por...

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Effects of High Bone Turnover on the Biomechanical Properties of the L3 Vertebra in an Ovine Model of Early Stage Osteoporosis

Cited by 19 publications

References 29 publications

Sheep model for osteoporosis: Sustainability and biomechanical relevance of low turnover osteoporosis induced by hypothalamic–pituitary disconnection

Sheep model for osteoporosis: Sustainability and biomechanical relevance of low turnover osteoporosis induced by hypothalamic–pituitary disconnection

Biomechanical properties across trabeculae from the proximal femur of normal and ovariectomised sheep

Structural adaptation and intracortical bone turnover in an ovine model of osteoporosis

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