To cite this article: Brennan SO, Oliver J, Davis RL. Epigenetic, polymorphic and mutational (Aa167Arg fi Lys) contribution to a functionally abnormal fibrinogen. J Thromb Haemost 2011; 9: 1410-2.
In a patient with symptoms attributable to lumbar spine disease, computed tomography (CT) demonstrated the descending colon lying in an exceptionally posteromedial position. The colon, within the retroperitoneal fat, passed between the psoas major and quadratus lumborum muscles, thereby abutting the normal left L4 ventral ramus lateral to the L5 pedicle. Although it remains debatable whether this curious anatomical arrangement was responsible for this patient's symptoms, the case prompted us to see how often the colon was situated so posteromedially. Among 33 consecutive patients whose abdominal CT images were analyzed, this close anatomical relationship was seen in only one patient; it was not seen in any of 50 randomly selected patients undergoing magnetic resonance imaging (MRI) of the lumbar spine. As judged by CT measurements, the average position of the most posteromedial portion of the descending colon lies 5 mm anterolateral to a plane joining the anterolateral margins of the psoas major, quadratus lumborum, and iliacus muscles and 54 mm from the ventral ramus. 0 1993 Wiley-Liss, Inc.
SummaryUnintentional over-tightening of orthopaedic screws resulting in loss of screw purchase (“screw stripping”) is a potential complication during fracture fixation. This report describes the microstructural and radiographic effects on bone caused by stripping a 2.7 mm orthopaedic screw, and subsequent replacement in these stripped screw sites with either a 3.5 mm cortical or a 4.0 mm cancellous orthopaedic screws in both tapped and untapped holes. Over-tightening of a 2.7 mm screw resulted in shearing of the bone directly engaged by the screw threads. Additional fractures occurred in surrounding bone, primarily superficial subperiosteal saucer fractures in the cis cortex and to a lesser degree, in the subendosteum of the trans cortex. Bone damage was consistently more severe in the cis cortex. Salvaging stripped screw sites by insertion of a 3.5 mm or 4.0 mm screw resulted in additional fracturing and displacement, which was more severe in the untapped sites. Decreased holding power of screws placed in stripped screw sites could be attributed to collateral structural bone damage occurring during screw stripping and replacement screw application.Over-tightening of orthopaedic screws until mechanical failure (“screw stripping”) results in damage to cortical bone which extends beyond the outer thread diameter of the screw. Damage, most often subperiosteal saucer fractures, was greater in the cis cortex. The subperiosteal saucer fractures decreased the functional length of screw engagement of the larger replacement screws in the cortical bone, which may account for decreases in expected holding power.
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