A biomechanical study of a rigid plating system for sternal fixation

Median sternotomy, a procedure required for open-heart surgery, cardiac valve replacement and coronary bypass surgery, is the most commonly used surgical approach in cardiothoracic surgery. Complications associated with the traditional use of stainless steel sutures for sternal closure lead to poor sternal healing, sternal separation and dehiscence in 0.5 to 2.5% of all cases. Sternal dehiscence leads to discomfort, mediastinitis, osteomyelitis, and chronic sternal instability, and it is associated with a 10-40% mortality rate. Improving the mechanical stability of sternal fixation devices will facilitate better sternal healing and decrease the likelihood of complications associated with medial sternotomy. Based on healing of long bones, it has been suggested that rigid fixation devices promote faster sternal healing while reducing the likelihood of post-operative complications. Although metal plates are currently being used clinically to provide stable sternal fixation, no mechanical data has been published to support the assertion that plates provide a more rigid fixation than wires. Our ultimate goal is to determine the optimal plating configuration for rigid fixation in terms of the location, type, and number of metal plates. The purpose of this preliminary study was to determine the stability of fixation of a sternum following midline sternotomy using three metal plates.