A biomechanical study of 4 different sternum closure techniques under different deformation modes.

Abstract

This study experimentally compares the efficiency of the 4 most preferred sternal closure tehniques, in 3 different deformation modes of the chest. Polyurethane sternum models fixed by conventional wiring, steel band, ZipFix band and figure-8 wiring are tested statically under lateral distraction, longitudinal shear and torsional deformation modes. As a result, load-deformation curves are obtained. The closure efficiency of the techniques is then compared with respect to allowable load (corresponding to 2 mm displacement), rigidity, rupture load and rupture displacement. A comparison in terms of cost and ease of application has also been presented. The highest allowable load and rigidity values in simple tension and longitudinal shear are obtained by the steel and ZipFix band techniques, respectively. In torsion mode, the highest allowable load is provided by the ZipFix band and the highest rigidty is attained by the steel band technique. The highest rupture loads under simple tension, longitudinal shear and torsion modes are observed in ZipFix, steel band and conventional wiring, respectively. Steel band closure provides the least rupture displacement in simple tension as well as torsion, whereas ZipFix bands give the smallest rupture displacements in longitudinal shear. However, in every loading mode there were no statistically significant differences in allowable load, rigidity and rupture load values between the closure methods, and only rupture displacement values were statistically different for each method. Our results showed that conventional wiring is the most advantageous closing method when compared to the others.