Development of a membrane-covered hip implant to prevent osteolysis

Total hip replacement (THR) is one of the most frequently performed orthopedic surgeries. Despite the fact that THR is a successful operation with relatively high survival rates, a large absolute number of revisions are needed. The main reason for revision is aseptic loosening, often caused by osteolysis, the process of bone resorption due to the excessive presence of particles, mostly PE particles originating from the implant. Attempts towards prevention of osteolysis include the use of metal or ceramic bearings, or of highly cross-linked PE. Because this still does not give satisfying results, a solution to prevent osteolysis is of utmost importance to increase the survival rate of THR. It is the aim of this PhD research to develop a membrane-covered hip implant. The membrane prevents the PE particles from moving outside the joint, into the bone structures. In order to prevent an increased particle concentration inside the joint capsule, it is the aim to develop a membrane that permits fluid flow through it, but filters out the PE particles and holds them within the material. The biomechanical development includes the mechanical design. Numerical models will be used to simulate the particle motion inside the body, and the effect of a membrane. As an outcome, particle concentrations in various areas surrounding the implant can be predicted and their influence on changing bone characteristics can be studied. Biomechanical tests will have to be performed for validation of the model without and with the membrane. The results of these experiments will be fed back to the model to result in an improved membrane design, optimized for longevity.