Combined nanoindentation testing and scanning electron microscopy of bone and articular calcified cartilage in an equine fracture predilection site.
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Condylar fracture of the third metacarpal bone (Mc3) is the commonest cause of racetrack fatality in Thoroughbred horses. Linear defects involving hyaline articular cartilage, articular calcified cartilage (ACC) and subchondral bone (SCB) have been associated with the fracture initiation site, which lies in the sagittal grooves of the Mc3 condyle. We discovered areas of thickened and abnormally-mineralised ACC in the sagittal grooves of several normal 18-month-old horses, at the same site that linear defects and condylar fracture occur in older Thoroughbreds and questioned whether this tissue had altered mechanical properties. We embedded bone slices in PMMA, prepared flat surfaces normal to the articular surface and studied ACC and SCB using combined quantitative backscattered electron scanning electron microscopy (qBSE) and nanoindentation testing: this allowed correlation of mineralisation density and tissue stiffness (E) at the micron scale. We studied both normal and affected grooves, and also normal condylar regions. Large arrays of indentations could be visualised as 2-dimensional maps of E with a limit to resolution of indentation spacing, which is much larger than qBSE pixel spacing. ACC was more highly mineralised but less stiff in early linear defects than in control regions, while subchondral bone was more highly mineralised and stiffer in specimens with early linear defects than those without. Thus both ACC and SCB mineralisation may be abnormal in a class of early linear defect in 18-month-old Thoroughbred horses, and this may possibly contribute to later fracture of the Mc3 condyle. (+info)
Reduced trabecular bone mineral density and cortical thickness accompanied by increased outer bone circumference in metacarpal bone of rheumatoid arthritis patients: a cross-sectional study.
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Unstable metacarpal and phalangeal fractures: treatment by internal fixation using AO mini-fragment plates and screws.
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BACKGROUND: Accurate open reduction and internal fixation for metacarpal and phalangeal fractures of the hand is required in less than 5% of the patients; otherwise, closed treatment techniques offer satisfactory results in most of these cases as these fractures are stable either before or after closed reduction. AO mini-fragment screws and plates, when used in properly selected cases, can provide rigid fixation, allowing early mobilization of joints and hence good functional results while avoiding problems associated with protruding K-wires and immobilization. The advantages of such internal fixation urged us to undertake such a study in our state where such hand injuries are commonly seen. METHODS: Forty patients with 42 unstable metacarpal and phalangeal fractures were treated with open reduction and internal fixation using AO mini-fragment screws and plates over a period of three years in a prospective manner. RESULTS: The overall results were good in 78.5% of cases, fair in 19% of cases and poor in 2.5% of cases, as judged according to the criteria of the American Society for Surgery of the Hand. CONCLUSION: This technique is a reasonable option for treating unstable metacarpal and phalangeal fractures as it provides a highly rigid fixation, which is sufficient to allow early mobilization of the adjacent joints, thus helping to achieve good functional results. (+info)
Relative bioavailability of phosphorus in inorganic phosphorus sources fed to growing pigs.
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Early changes in bone mineral density measured by digital X-ray radiogrammetry predict up to 20 years radiological outcome in rheumatoid arthritis.
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