Archives of orthopaedic and trauma surgery
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Animal studies can provide important information in the evaluation of new techniques and prosthetic designs in orthopedics. As a prerequisite they must parallel as closely as possible the human conditions they are modeling. An arthritic sheep model simulating the human clinical situation has previously been designed and reported by Phillips and Gurr. ⋯ Only one of the 12 cases showed postoperative avascularity of the femoral head. Radiologic follow-up and histologic examination showed features consistently and strikingly similar to those seen in human practice. The sheep hip with simulated arthritis provides a sensitive, clinically reproducible model for the future study of other arthroplasty types and problems.
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Arch Orthop Trauma Surg · Jan 1990
Ultrastructural changes in synovium and cartilage in experimental hemarthrosis in dogs.
This paper reports electron-microscopic findings in synovium and cartilage in experimental hemarthrosis in dogs. The results are correlated with the total amount of glycosaminoglycans in the cartilage matrix, measured by the fixed-charge density method. Very early, changes are seen in the synoviocytes, similar to synovitis, and especially phagocytosis of iron-containing particles forming secondary lysosomes or siderosomes. Siderosomes are also a constant feature seen in the chondrocytes, together with changes in the rough endoplasmic reticulum and in the glycogen content, correlating with the changes in the ground substance.
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Twenty-nine patients were examined by magnetic resonance imaging for various lesions of the spine. The results of these scans were compared with those of plain radiographs, computertomographs, and radionuclide bone scans. ⋯ Characteristic changes of the signal patterns for inflammatory and tumorous lesions were not observed. The differentiation of these lesions will presently continue to have to be based on morphological criteria.
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Arch Orthop Trauma Surg · Jan 1990
Pathology of the bone-cement interface in loosening of total hip replacement.
The histopathology of the bone-cement interface in nine retrieved hip prostheses is reported. Three cases presented features similar to those observed by Charnley in highly successful implants, and they were classified as stable prostheses, although signs of periprosthetic bone resorption were already present. ⋯ The polymorphous features of this connective membrane probably resulted from instability and movement at the bone-cement and stem-cement interfaces. On the basis of the pathological changes observed in the study, the process of loosening must be far advanced before it is detected on radiographs; it is suggested that scintigraphy is the best noninvasive technique to demonstrate macrophage activation and increased bone remodeling around the cement in the early phases of loosening.