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  • 1
    Electronic Resource
    Electronic Resource
    Role of trabecular morphology in the etiology of age-related vertebral fractures (1993)
    Springer
    Calcified tissue international 53 (1993), S. S14 
    Details
    ISSN: 1432-0827
    Keywords: Stereology ; Morphology ; Osteoporosis ; Vertebral body
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Osteoporotic compression fractures of the spine differ from most other age-related fractures in that they usually are associated with minimal trauma and with loads no greater than those encountered during normal activities of daily living. With aging and osteoporosis, there is progressive resorption of bone, resulting in reductions in bone density, thinning of trabeculae, and loss of trabecular contiguity. These changes in trabecular bone structure are associated with losses in bone strength which are disproportionate to the reductions in bone mass alone. To explain this disproportionate loss of bone strength, the prevailing opinion is that density reductions in the vertebral centrum are accompanied by a reduction in the number of trabeculae, by preferential resorption of horizontal trabeculae, and by hypertrophy of the remaining vertical trabeculae. To evaluate this view of vertebral morphology, we performed three-dimensional stereological analysis of trabecular bone extracted from midsagittal sections of first lumbar vertebral bodies from 12 donors spanning an age of 27–81 years. We found that both the number (R2 = 0.63,P 〈 0.01) and thickness (R2 = 0.91,P 〈 0.01) of trabeculae decreased linearly with density (as expressed by bone volume fraction) whereas the spacing between the trabeculae (R2 = 0.61,P 〈 0.01) increased reciprocally. There were more vertical trabeculae with transverse trabeculae at all densities, and the number of vertical trabeculae changed with density at twice the rate of the number of transverse trabeculae (P 〈 0.001). These data do not support the prevailing view that there is preferential resorption of horizontal trabeculae or hypertrophy of the remaining vertical trabeculae. Bone density was also a strong (R2 = 0.90,P 〈 0.01) power law function of the ratio of trabecular thickness to mean intertrabecular spacing. From buckling theory, the critical buckling load of a trabecula is related to this ratio of trabecular thickness to effective length. The changes in trabecular morphology observed with decreasing bone density thus pose a “triple threat” to the strength and stability of vertebral trabecular bone, as not only are there fewer trabeculae, but the remaining trabeculae are both thinner and longer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01673396
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  • 2
    Electronic Resource
    Electronic Resource
    Ultrasound and densitometry of the calcaneus correlate with the failure loads of cadaveric femurs (1995)
    Springer
    Calcified tissue international 56 (1995), S. 99-103 
    Details
    ISSN: 1432-0827
    Keywords: Calcaneal ultrasound ; Bone mineral density ; Femoral strength ; Hip fracture ; Osteoporosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract We assessed the bone mineral density (BMD) of 16 matched sets of cadaveric proximal femurs and feet using dual-energy x-ray absorptiometry (DXA). We also estimated the femoral neck length from the DXA scans. Quantitative ultrasound densitometry was used to measure the velocity of sound and broadband ultrasound attenuation (BUA) in the calcaneus of each foot. The proximal femurs were then tested to failure in a loading configuration designed to simulate a fall with impact to the greater trochanter. Femoral neck BMD and trochanteric BMD were strongly associated with the femoral failure load (r2=0.79 and 0.81, respectively; P〈0.001), whereas femoral neck length was modestly correlated with femoral failure load (r2=0.27, P=0.04). Calcaneal BMD (r2=0.63, P〈0.001) and BUA (r2=0.51, P=0.002) were also significantly associated with femoral failure load. Given the small sample size, we were unable to detect differences in the strength of the correlations between the independent parameters and femoral failure load. Using linear multiple regression analyses, the strongest predictor of femoral failure load was a combination of femoral neck BMD and femoral neck length (R2=0.85, P〈0.001). Thus, it appears that both femoral and calcaneal bone mineral properties may be useful for identifying those persons at greatest risk for hip fracture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296338
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  • 3
    Electronic Resource
    Electronic Resource
    Ovariectomy decreases the bone area fraction of the rat mandible (1995)
    Springer
    Calcified tissue international 56 (1995), S. 305-310 
    Details
    ISSN: 1432-0827
    Keywords: Osteoporosis ; Ovariectomy ; Oral bone loss ; Biomechanics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Although osteoporosis is a major public health concern, the effect of this condition on oral bone has not been determined. Using the ovariectomized rat, we tried to determine if estrogen depletion and aging affect the mandible of the rat. Sixty-one ovariectomized (ovx) and shamoperated (sham) 6-month-old Sprague Dawley rats were divided equally into six groups. The baseline, adult, and old rats were euthanized 14, 114, 200 days post-ovx, respectively. The bone mineral density of the mandible was measured using high resolution dual energy x-ray absorptiometry. The failure load and stiffness of the mandible were measured in three-point bending. The bone area fraction and area moment of inertia of digitized images of mandible sections were measured using image analyzing software. In adult rats, ovx led to a 15% and 28% increase in failure load and stiffness, respectively, but no change in bone area fraction or bone mineral density. In the old rats, ovx led to an 8% decrease in bone area fraction, but no change in failure load, stiffness, or bone mineral density of the mandible. In the ovx rats, aging led to a 20% and 7% decrease in stiffness and bone area fraction of the mandibles in the old rats compared with that in the adult rats. In the adult ovx rats, the increase in structural properties of the mandible may be a consequence of an increase in masticatory function as it has been reported that ovx rats eat approximately 10% more than sham controls. Overall, ovx led to a decrease in bone area fraction in the mandible and a decrease in bone area fraction and stiffness in the mandible of the aging rat. These findings indicate that in this model, estrogen depletion affects the mandible and may contribute to oral bone loss and that this loss may be accentuated with aging.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318051
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