Custom made sternocostal implant design and manufacturing by using 3D printing technology

The sternocostal joints are the joints located in the thoracic region between the first seven ribs and the sternum. Some of the tumors, infections, and traumas occurring in the chest wall result in reconstruction of the sternum and its associated sternocostal joints. In order to enhance the patient's quality of life, sternocostal implants made of anatomical and material compatible with the tissue of the person to be used to replace the removed damaged area. Unlike the standard implants in the market, the production of implants specific to the person's condition not only reduces the risks of the surgeries but also facilitates the job of the surgeons. These implants, which are designed in computer aided technoloiges, can be turned into tangible 3-D models thanks to 3-D printer technologies, which are accepted as additive manufacturing. In this study, the production and design stages of a custom sternocostal joint implant with SLS (Selective Laser Sintering), which is a powder-based additive manufacturing method of 3-D manufacturing technologies, was examined and a new implant design was proposed. In the analysis program of a sternocostal implant made of Ti-6Al-4V material created by MDMC (Medical Design and Manufacturing Center, University of Health Sciences, Gülhane, Ankara) and implanted to the patient, finite element analysis was performed and the loads and stress values on the implant were measured. In the analysis, specific bounded conditions were created and stress, strain and deformation values on the implant were examined under the same boundary conditions in all models. According to the results, it was observed that when a CPR force is applied to the implant model integrated into the rib cage, the implant can withstand this force, and the stress results remain below the yield strength of titanium, so it does not cause permanent deformation of the implant. Some sternocostal implants designed to date in the world and in our country have been examined within the scope of the study, design differences and improvements have been made on the analyzed sternocostal implant as a result of the researches, and their analyzes have been carried out. Within these design differences, the implant was divided into three parts and the parts were combined with screws, and the results were evaluated by applying the same boundary conditions in the analysis program. According to the results of the analysis, it was observed that the stress was concentrated around the holes with the screws and the number of screws in the designs was increased, the analysis results were compared and the results were interpreted. The study is aimed to guide the sternocostal implant studies that will be designed from now on.