The mechanical behavior of a new designed hip spacer

Within this project a new hip spacer made of antibiotic impregnated bone cement used in two-stage treatment of infected hip joints was developed. As the material strength of bone cement is limited, fractures occurred in the past and led to important complications, so that a reinforcement of titanium was designed. Different shapes for this reinforcement were investigated and tested. The loading procedure was close to the ISO 7206-4, though small adaptation was made. An inserted rod of titanium grade II increased the collapse load up to 1000 - 1300 N, but considering a maximum expected force of about three times body weight, a "full-stem" reinforced spacer was created with titanium endoskeleton and a coating of minimum 2 mm PMMA. A finite element model was used to design this device so that finally a mobile and functional joint through the treatment course can be guaranteed. This new spacer is moulded during surgery and thus may be adapted optimal to the patients infect and his individual needs.