A biomechanical study of median sternotomy closure techniques.
OBJECTIVE
Sternal dehiscence is a complication of median sternotomy incisions with high mortality and morbidity. Different techniques of sternal closure have been described. Rigid fixation of the sternum results in earlier union. We measured the rigidity of sternotomy fixation using a mechanical model in order to differentiate different techniques of sternal closure using their biomechanical characteristics.


METHODS
We measured the force-displacement curves of six different fixation techniques using a metal sternal model using a computerized materials-testing machine. We tested straight wires (the most commonly used surgical technique), figure-of-8 wires, 'repair' technique (used when a wire breaks), Ethibond, Sterna-band and a 'multitwist' closure described for the first time.


RESULTS
At 20 kg force, twisted wires used for sternotomy closures start to untwist. The most rigid closure was a multitwist closure that displaced only 0.37 mm at a force of 20 kg. Straight wires displaced 0.78 mm, figure-of-8 wires 1.20 mm, Sterna-band 1.37 mm, repair wires 5.08 mm, Ethibond 9.37 mm. The single factor Anova test for the rigidity of the different closures had P-values <0.0001.


CONCLUSIONS
We applied a mathematical model to calculate chest wall forces during coughing, in order to determine the force placed upon a sternotomy closure. We conclude that severe coughing may cause wires to untwist. We discuss potential applications of different wire closures based on their characteristics.
Casha
A R
AR
Department of Cardiothoracic Surgery, Leeds General Infirmary, UK.
Yang
L
L
Kay
P H
PH
Saleh
M
M
Cooper
G J
GJ
D001696:Biomechanical Phenomena; D004867:Equipment Design; D006801:Humans; D008954:Models, Biological; D013249:Sternum / Q000601:surgery*; D013536:Suture Techniques / Q000295:instrumentation; D013537:Sutures; D013718:Tensile Strength; D013909:Thorax / Q000502:physiology*