Sternal plating for primary and secondary sternal closure; can it improve sternal stability?

<p>Abstract</p> <p>Background</p> <p>Sternal instability with mediastinitis is a very serious complication after median sternotomy. Biomechanical studies have suggested superiority of rigid plate fixation over wire cerclage for sternal fixation. This study tests the hypothesis that sternal closure stability can be improved by adding plate fixation in a human cadaver model.</p> <p>Methods</p> <p>Midline sternotomy was performed in 18 human cadavers. Four sternal closure techniques were tested: (1) approximation with six interrupted steel wires; (2) approximation with six interrupted cables; (3) closure 1 (wires) or 2 (cables) reinforced with a transverse sternal plate at the sixth rib; (4) Closure using 4 sternal plates alone. Intrathoracic pressure was increased in all techniques while sternal separation was measured by three pairs of sonomicrometry crystals fixed at the upper, middle and lower parts of the sternum until 2.0 mm separation was detected. Differences in displacement pressures were analyzed using repeated measures ANOVA and Regression Coefficients.</p> <p>Results</p> <p>Intrathoracic pressure required to cause 2.0 mm separation increased significantly from 183.3 ± 123.9 to 301.4 ± 204.5 in wires/cables alone vs. wires/cables plus one plate respectively, and to 355.0 ± 210.4 in the 4 plates group (p < 0.05). Regression Coefficients (95% CI) were 120 (47–194) and 142 (66–219) respectively for the plate groups.</p> <p>Conclusion</p> <p>Transverse sternal plating with 1 or 4 plates significantly improves sternal stability closure in human cadaver model. Adding a single sternal plate to primary closure improves the strength of sternal closure with traditional wiring potentially reducing the risk of sternal dehiscence and could be considered in high risk patients.</p

Bioavailability and Bioaccessibility of Hydrophobic Organic Contaminants in Soil and Associated Desorption-Based Measurements

Many publications on contaminant bioavailability in soils often state that the use of total contaminant concentrations in risk assessment is an overly conservative approach. Such conservatism makes traditional risk assessment approaches and contaminated land decision-making expensive. The risk-based approach to contaminated land management strives to identify and manage the potential risks of significant harm being caused to humans and ecological receptors, following exposure to contaminated land. Risk-based approaches are more cost-effective than the traditional approaches from the perspective of contaminated land management. Contaminant bioavailability or bioaccessibility is one of the critical concepts that underpins risk-based approaches to contaminated land management. Bioavailability describes the fraction of the total contaminant concentration that desorbs from soil and is immediately available to cause harm to a living organism, after passing through the organism’s membrane. Bioaccessibility describes what is available and potentially available under natural environmental conditions and during realistic timeframes. The reliable measurements of either contaminant bioavailability or bioaccessibility is therefore critical; in this regard, a thorough understanding of contaminant sequestration and desorption behaviour is required. This chapter discusses the fate of HOCs in soils, bioavailability and bioaccessibility of organic contaminants and their associated desorption-based measurements