Mechanical Strength of Used Ceramic Femoral Heads

Twenty retrieved 32mm alumina ceramic femoral heads were investigated for surface structure or mechanical strength. All heads were retrieved at revision hip surgery after (on average) eight and a half years in vivo. In all cases cementless stems (titanium-alloy) and spherical acetabular components with a polyethylene inlay had been used. For surface analysis EDX analysis and scanning electron microscopy were used. Fracture strength of the heads according to ISO 7206–5 was measured and a fracture analysis was performed. Frequently appositional metal marks on the ceramic surface were found. These were allocated to three zones. Depending on surface zone different metal composites were detected. Their possible origin and relevance are discussed. The fracture strength ranged from 46 kN to 104 kN. Ceramic femoral heads of high quality seem to maintain a high degree of fracture strength for a considerable period after implantation.