Faculty Advisor

Billiar, Kristen


In 2006 nearly 700,000 open heart surgeries were performed, each of which required a surgical bisection of the sternum. After surgery, the sternum must be fixated back together a process that usually uses cerclage wires. In a small subset of patients, these wires are ineffective at providing fixation which leads to malunion and infection of the sternum. Rigid fixation is proposed to be a better solution; however screw-plate systems are not currently optimized for the sternum. Different screw types and depths were assessed by cyclic loading (0 to 50N) in osteoporotic human sternum for 15,000 cycles. Using these results, an optimal rigid fixation system was proposed. A composite screw with novel locking head was designed that was shown to minimize displacement based on a proof of concept.


Worcester Polytechnic Institute

Date Accepted

April 2009


Biomedical Engineering

Project Type

Major Qualifying Project



Advisor Department

Biomedical Engineering