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KELLEY M. THIEMAN DVM ANTONIO POZZI DMV MS Diplomate ACVS HANG-YIN LING PhD DANIEL D. LEWIS DVM Diplomate ACVS MARYBETH HORODYSKI EdD ATC 《Veterinary surgery : VS》2009,38(7):803-810
Objective— To evaluate the biomechanical effects of 5 types of meniscal lesions on contact mechanics in the canine stifle.
Study Design— Experimental study.
Animals— Cadaveric canine stifles (n=12 pair).
Methods— Medial meniscal lesions (radial, vertical longitudinal, nonreducible bucket handle, flap, and complex tears) were simulated in cadaveric stifles. A contact map was recorded from each tear type and contact area (CA) and peak contact pressure (PCP) from each tear type were compared.
Results— A significant difference in PCP was detected between control and nonreducible bucket handle, flap, and complex tears. PCP increased by >45% in nonreducible bucket handle, flap, and complex meniscal tears when compared with control. No significant difference was found in PCP between control and radial and vertical longitudinal tears. No significant difference was found in CA between any of the meniscal conditions.
Conclusions— Nonreducible bucket handle, flap, and complex tears cause a significant increase in PCP. Radial and vertical longitudinal tears had a minimal impact on the contact pressures of the medial compartment of the stifle.
Clinical Relevance— Based on this ex vivo model, we support the clinical recommendation of debriding nonreducible bucket handle, flap, and complex tears because the injured portion of the meniscus no longer contributes significantly to the function of the meniscus. Radial and vertical longitudinal tears do not cause a change in contact mechanics allowing consideration of nonsurgical treatment and meniscal repair, respectively. Future experimental and clinical studies should aim to refine the treatment of specific meniscal injuries. 相似文献
Study Design— Experimental study.
Animals— Cadaveric canine stifles (n=12 pair).
Methods— Medial meniscal lesions (radial, vertical longitudinal, nonreducible bucket handle, flap, and complex tears) were simulated in cadaveric stifles. A contact map was recorded from each tear type and contact area (CA) and peak contact pressure (PCP) from each tear type were compared.
Results— A significant difference in PCP was detected between control and nonreducible bucket handle, flap, and complex tears. PCP increased by >45% in nonreducible bucket handle, flap, and complex meniscal tears when compared with control. No significant difference was found in PCP between control and radial and vertical longitudinal tears. No significant difference was found in CA between any of the meniscal conditions.
Conclusions— Nonreducible bucket handle, flap, and complex tears cause a significant increase in PCP. Radial and vertical longitudinal tears had a minimal impact on the contact pressures of the medial compartment of the stifle.
Clinical Relevance— Based on this ex vivo model, we support the clinical recommendation of debriding nonreducible bucket handle, flap, and complex tears because the injured portion of the meniscus no longer contributes significantly to the function of the meniscus. Radial and vertical longitudinal tears do not cause a change in contact mechanics allowing consideration of nonsurgical treatment and meniscal repair, respectively. Future experimental and clinical studies should aim to refine the treatment of specific meniscal injuries. 相似文献
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Microfossils have been discovered in cavity-fill and replacement silica that occurs between chert-breccia clasts in 1200-million-year-old paleokarst at the top of the Mescal Limestone, central Arizona, and in approximately 800-million-year-old paleokarst at the top of the Beck Spring Dolomite, southeastern California. Microbial communities on Precambrian (>550 million years ago) land may have been extensive enough to affect weathering, erosion, sedimentation, and geochemical processes. 相似文献
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Carbonaceous shales of the late Precambrian Chuar Group of the Grand Canyon, Arizona, contain abundant and well-preserved chitinozoans. The occurrence of these distinctive, tear- and flask-shaped microfossils, the oldest chitinozoans now known and the first to be reported from the Precambrian, seems to suggest that heterotrophic protists (or primitive metaozoans) were extant at least as early as about 750 +/- 100 million years ago. 相似文献
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Carbonaceous shales of the Middle Proterozoic Newland Limestone, Belt Supergroup, Little Belt Mountains, Montana, contain abundant and well-preserved filamentous and spheroidal microfossils. The filamentous forms, ranging from less than 1 to 12 micrometers in width, are interpreted as representing the preserved sheaths of at least four species of nostocalean cyanophytes. The spheroidal forms, ranging from 15 to 108 micrometers in size, are evidently planktonic forms and are tentatively interpreted as representing the encystment stage of eukaryotic algae. The Newland microbiota is adaptable to petrographic thin-section work, and useful for evaluating the potential of such microfossils for intercontinental biostratigraphic correlation. It is the oldest shale-facies microbiota presently known from North America. 相似文献