Ceramic macrostructured acetabular liner integratingdirectly into Bone: Implant design, manufacturing, and in vitro investigations

The development of new ceramic materials for medical applications enhances the possibilities of implant design. Monolithic acetabular liners based on zirconia-platelet-toughened alumina with a macrostructured backside could increase patient mobility and prosthesis life span. This study developed a ceramic liner with an articulating diameter of 40 mm and a wall thickness of 3 mm. A macroporous coating with an average pore size of 300-400 μm was deposited at the backside of the liner during the manufacturing process. Cytotoxity testing, microscopic imaging, as well as mechanical examinations (four-point bending test; compressive strength test) were performed to characterize the properties of the implant in vitro. Examinations of the impact resistance and luxation stability were also conducted. The macrostructured backside could be manufactured homogeniously. No cytotoxic effects were detected in cell culture experiments. The mechanical examinations were passed without delamination of the coating. No cracks due to impact loading appeared for any of the samples tested. The range of motion of the joint and luxation stability both increased significantly compared to those of an established liner with a 28-mm diameter. The results show that the developed liner has outstanding mechanical and tribological properties.