Biomechanical analysis of topology-optimized and bioinspired designs of sternal reconstructions under physiological and pathological loads

• Solid, porous, honeycomb, pillar-core, and topology-optimized PEEK sternal implants were evaluated under breathing, coughing, and blunt trauma. • All implants performed adequately during normal breathing, but significant performance differences emerged under intense coughing and trauma. • Solid, porous, and porous-solid core implants showed high stress levels and greater fatigue risk, especially under blunt trauma. • Pillar-core and topology-optimized designs achieved a superior balance between strength and flexibility. Sternal reconstruction following tumor resection, trauma, or infection poses significant biomechanical challenges due to the need to restore structural stability, respiratory function, and protect underlying organs. The objective of this study is to evaluate and compare the biomechanical performance of PEEK-based topology-optimized and bioinspired sternal implant designs (solid, porous, honeycomb, and pillar-core) under physiological and pathological loading using finite element analysis (FEA). A patient-specific chest wall model incorporating each implant design was developed and tested under quiet breathing, intense coughing, and anterior blunt trauma. Stress and strain distributions were evaluated in the adjacent ribs, costal cartilages, and lung tissues. Additionally, the long-term structural integrity of all implants and corresponding fixation screws was assessed through fatigue analysis. The results showed that all sternal implant designs maintained safe stress and strain levels on adjacent structures during quiet breathing. Under intense coughing and trauma, the honeycomb design and porous design with a solid core exhibited excessive stress and strain levels in adjacent structures. In contrast, the porous design with a pillar core and topology-optimized design demonstrated superior load distribution, providing enhanced protection to adjacent anatomical tissues. These designs also showed optimal biomechanical performance, offering a promising balance between structural durability and biological compatibility.