Design of Flexible Implants for Preservation of Physiological Mobility Exploiting Additive Manufacturing

Abstract

Due to tumors or bone fractures caused by high mechanical impact, the affected tissue has to be removed. The implantation of a stabilizing replacement is a common solution for defect bridging and support of bone ossification. Preserving the physiological mobility after the treatment could prevent stress shielding or overload of the surrounding muscles and ligaments. [1]In case of a critical vertebral body defect, the body and its attached disks have to be removed. Thereafter the adjacent vertebral bodies are braced together resulting in limited physiological spine movability. A flexible implant adapted to and preserving the patient-specific physiological spine mobility would be a desirable solution. [2] [3]To realize such an implant additive manufacturing (AM) can be used as a key technology. AM offers the following advantages: The build-up of almost any desired complex geometry shape, without additional costs. A monolithic geometry with enhanced functionalities combined in only one part and one material. A cost-efficient implant individualization based on patient specific requirements. [4]Relating to flexibility, the integration of solid state hinges tailored to the patient specific physiological mobility is possible. Hereby, assembly work is neglectable and abrasion will be prevented due to the absence of friction partners. A challenge to overcome will be the durability of the design. It is limited by the fatigue of the material caused by implant motion.