An electronic-engineered sensory sternal retractor aimed at post-sternotomy pain reduction

The median sternotomy can rise in rib and/or sternum micro/macro-fractures and/or brachial plexus injuries, which can even evolve in chronic pain with significant impact on patient’s quality life. Post-sternotomy chronic pain is recognized as a multifactorial complex issue, and it has been assessed that sternum retraction forces, applied by the surgeons, can be considered one of these factors. In order to investigate the behavior of these forces, we developed a reliable and sterilizable system, to monitor the retraction forces along the hemisternums. Therefore, a Finochietto sternal retractor was instrumented by means of ultra-thin force sensors interfaced with ad hoc electronic circuitry. Two different sets of sensors were adopted, one of which able to support autoclave operating conditions. In-vitro tests were performed by means of a made on purpose dummy. The instrumented retractor allows monitoring the force exerted on both the arms during the opening procedure. Force versus time patterns were acquired and stored, and so we determined how the forces are distributed in terms of their mean, maximum and plateaus. Results demonstrate the reliability of the instrumented retractor in measuring forces, up to 400 N. Cost-effectiveness and feasibility can be considered further additional values of the proposed instrumented retractor.