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Results for “Haversian System”

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At least 253 records · Page 14Linked to original sources
PubMed1991

Nutrient foramina in the shafts of lower limb long bones: situation and number.

The location and number of the diaphysial dominant nutrient foramina in 305 specimens of the human lower limb long bones were examined. The diaphysial nutrient foramina on the femur were located at between 26.7-84.4% of the total length; while on the tibia between 11.0-67.2%; and on the fibula between 29.8-67.8% of the total length. The number of the diaphysial nutrient foramina and their distribution on the faces of each bone was also studied.

Femur↗
PubMed1977

Relations between tensile impact properties and microstructure of compact bone.

Standardized human and beef femoral compact bone specimens were tested in tensile impact and the dynamic mechanical properties were determined. The microstructure of 45 beef and 47 human bone specimens were examined histologically to determine if there is a structural basis to account for strength differences in the bone samples. Strong negative correlations were obtained between the maximum stress and the percentage area of secondary osteons in each specimen. For human bone samples, the energy absorption capacity and the modulus of elasticity were also found to have strong negative correlations with the percentage area of secondary osteons present in each specimen. Linear regression equations were obtained describing the impact strength properties in terms of the percentage areas of secondary osteons and cavities in the samples. Fracture surfaces of the tested bone specimens were examined in a scanning electron microscope. Most surfaces exhibited a fairly rough texture indicating a quasi-cleavage type of failure. Fractographic analysis of bone fracture surface was helpful in understanding the micromechanics of bone fracture.

Animals↗
PubMed1993

Architecture in cortical bone and ultrasound transmission velocity.

The square of ultrasound transmission velocity in a material is correlated to the modulus of elasticity, which is an indicator of its mechanical properties. This might make the measurement of ultrasound transmission velocity useful in the noninvasive diagnosis of bone diseases. Bone, however, is not an isotropic material but is architecturally structured. The aim of our study was to investigate and especially to quantify the influence of architecture in cortical bone on ultrasound transmission velocity. Twenty-two rectangular, flat specimens of cortical bone were prepared from diaphysis of fresh pig radius. Ultrasound transmission velocity was measured parallel and perpendicular to direction of Haversian channels. It was found to be 3647 +/- 41 m/s parallel to and 2821 +/- 29 m/s perpendicular to Haversian channels respectively (p < 0.001). Our results clearly indicate that there is an important influence of architecture in cortical bone on ultrasound transmission velocity which has to be taken into account in its clinical use.

Animals↗
PubMed1983

X-ray diffraction analysis of transversal osteonic lamellae.

When isolated osteon samples are submitted to wide-angle X-ray diffraction, it is not possible to detect any preferential orientation of the hydroxyapatite crystallites of the lamellae with transversally arranged fiber bundles. So a complete and exhaustive X-ray diffraction analysis of an osteon needs adequately prepared osteonic subunits. For the present investigation, 2 types of samples were prepared from longitudinal and alternate osteons: osteonic radial sections and isolated straightened transversal lamellae. An X-ray diffraction microcamera has been used with a rotating anode X-ray generator. In accordance with the data provided by the polarizing microscope, the orientation of crystallites runs parallel to the osteon axis in longitudinally structured osteons, whereas in alternate osteons the orientation changes by about 90 degrees in successive lamellae. Neither crystallites associated with the collagen fibrils that run alongside the osteocyte canaliculi nor those associated with the fibrils that run transversally in longitudinally structured osteons are revealed by X-ray diffraction, because there are so few of them.

Crystallization↗