Rationale and Options for Choosing an Optimal Closure Technique for Primary Midsagittal Osteochondrotomy of the Sternum. Part 1: A Theoretical and Critical Review of Functional Anatomy, Biomechanics, and Fracture Healing.

The sternum is central in binding the bilateral costal structures to form the anterior wall of the thorax. The airtight subatmospheric pressure cavity of the thorax during respiration and episodes of cough produces significant dynamic forces acting perpetually on its walls, influencing functions of the contained viscera. The embryonic development of the sternum concurs with that of the heart and parts of the pectoral girdle. Any imperfection of the sternum, whether congenital or iatrogenic, can significantly compromise the normal physiology of the thoracic wall and cardio-respiratory systems. Midsagittal osteochondrotomy (division) of the sternum is a necessary step to access the mediastinum for an open cardiac procedure. To return the thorax to its normal function, it is imperative that surgeons have thorough working knowledge of the surgical anatomy of the sternum and the biomechanics of an intact and disrupted thoracic wall. Patient-based outcome measures of an index cardiac surgery can only be considered conclusive if the divided sternum heals over time to have full benefit of the surgery. Here, the essential topographical anatomy and embryology of the sternum, thoracic biomechanics, fracture biology, and surgical access to the mediastinum are reviewed to provide a better understanding of the performance and importance of the healed sternum.