Method for CAD/CAM-based production of patient-specific anatomical bone surrogates from polyurethane rigid foams of different densities for various clinical applications

Abstract Physical models of bony areas are used in the medical environment for training, patient information or for various examinations. These are idealized average models which, however, do not reflect the individuality of a respective patient. Furthermore, the mechanical properties of the bony structure with cortical bone and cancellous bone are not considered in most models. A few manufacturers, such as SawBone, offer models and material blocks that approximate the properties of the bone. However, these are not patientspecific either. This paper presents a proposal for a method to create patient-specific physical bone models with CAD/CAM technologies that approximate shape and mechanical properties. The models are made of two different rigid polyurethane foams for cortical bone and cancellous bone. The methodical development includes the elaboration of a framework starting from the patient's CT data, through design derivation, to fabrication. Furthermore, a possible process for fabrication in the form of a demonstrator and its application in sawing tests will be demonstrated.