Force distribution in wire sternum sutures: the consequences for sternal closure rigidity.

BACKGROUND

This article provides a biomechanical analysis of the distribution of force in wire sutures used for sternal closure in cardiothoracic surgery.

MATERIAL/METHODS: The parameters we measured included displacement in the elastic region, plastic limit, and rupture load on the closure. Force distribution analysis was carried out for every kind of wire suture. A linear regression line of displacement as a function of increasing load was determined for each closure method.

RESULTS

Straight wire had less displacement at each load, figure-8 had medium, and interlocking multitwisted (IM) had the most displacement within the elastic range of the specimen. The differences between straight and interlocking multitwisted sutures were statistically significant. When the plastic limit was compared between straight and interlocking multitwisted closure, the differences were statistically significant. In the straight suture the forces used to approximate the sternal halves are perpendicular to the incision. With the figure-8 and interlocking multitwisted suture, the forces are dispersed and the effective approximation force is lower than that applied to the wires.

CONCLUSIONS

Straight wires provide good fixation stability for the durability of the sternum, and the somewhat lower strength could be compensated by increasing the number of sutures. The figure-8 and IM have better strength and are less likely to cut the sternum because of advantageous redistribution of shearing forces of the wire as compared to straight closures.