What Is the Sternum?

The sternum is a flat, elongated bone situated at the anterior midline of the thorax, forming the central structural element of the chest wall and serving as the attachment point for the costal cartilages of the upper ribs and the clavicles of the pectoral girdle. It functions as a bony shield for the heart, great vessels, and thymus gland while contributing to the mechanical integrity of the rib cage and the generation of respiratory pressure changes. In biomedical engineering and surgical practice, the sternum occupies a prominent role because cardiac surgery, tumor resection, and infection treatment frequently require its partial or complete reconstruction.

The sternum comprises three regions: the manubrium at the superior end, the body or gladiolus in the middle, and the xiphoid process at the inferior tip. These segments ossify separately and fuse progressively from adolescence through early adulthood. The bone receives its blood supply from the internal thoracic arteries, which run bilaterally along its posterior surface, a fact that governs both the healing of median sternotomy incisions and the consequences of wound infection.

Anatomy and Biomechanical Role

The sternum bears compressive and tensile loads transmitted through the ribs during breathing and through the shoulder girdle during upper-limb movement. Its stiffness is critical for maintaining the negative intrathoracic pressure required for lung inflation. Median sternotomy, the incision dividing the sternum longitudinally to expose the heart, is the most common approach in cardiac surgery and must be closed with stainless steel wires that hold the two halves in stable apposition while bone union occurs over six to eight weeks. The anatomy and its role in thoracic protection are documented in detail in NIH StatPearls on thoracic anatomy.

Surgical Reconstruction

Sternal resection is indicated for primary bone tumors, metastatic disease, and post-sternotomy infections such as mediastinitis. Reconstruction must restore chest wall rigidity to support respiratory mechanics, protect the mediastinum, and minimize dead space that predisposes to infection. The standard materials since the 1980s have included polymethyl methacrylate sandwiched between polypropylene mesh layers, which reproduces structural stiffness at low cost. Titanium systems, including rigid rib and sternal plates, offer superior strength and biocompatibility with complication rates in the range of zero to eleven percent across published series, as reviewed in PMC research on sternal reconstruction. Custom 3D-printed titanium prostheses manufactured from patient CT scans have emerged as an option for complex full-thickness defects, allowing precise contour matching and potential reduction of mechanical complications.

Bioengineering and Regenerative Approaches

Research in sternal bioengineering has moved toward implants that do more than passively replace removed bone. Bioglass-based scaffolds seeded with mesenchymal stem cells and loaded with bone morphogenetic protein 7 have demonstrated bone regeneration across large thoracic defects in preclinical models, combining structural support with biological repair. Biocompatible coatings that resist bacterial colonization are being evaluated as a strategy against sternal wound infection, which occurs in one to five percent of cardiac surgery cases and carries substantial morbidity. The intersection of additive manufacturing, biomaterials science, and stem cell biology in sternal repair is surveyed in PMC research on bioengineering approaches to sternal wound healing.

Applications

The sternum is central to clinical and engineering work in several domains, including:

• Median sternotomy access for coronary artery bypass, valve repair, and heart transplantation
• Oncological resection and reconstruction for primary and secondary chest wall malignancy
• Infection management following deep sternal wound complications from cardiac surgery
• Custom implant fabrication using 3D printing for complex thoracic reconstruction cases
• Biomechanical testing for prosthetic chest wall designs and closure wire configurations