Performance Requirements and Quality Control of Ceramic Femoral Ball Heads

Performance Requirements and Quality Control of Ceramic Femoral Ball Heads 

The femoral ball heads of hip endoprostheses made from bioinert ceramics such as alumina or zirconia, must withstand high mechanical stresses, resorption/cor-rosion by aggressive body fluids, and abrasive wear over the lifetime of the implant in the human body, for perhaps 15-20 years. Some important properties of ceramic femoral ball heads are listed in Table 10.7 (WiUmann, 1995). 

The wear performance of the sliding couple ceramic femoral ball/acetabular cup liner is crucially important, as the synovial fluid lubricant that is present in the natural hip joint is absent from the artiflcial system. Hence, the coefficient of friction must be as low as possible. Data relating to the linear wear of clinically established wear couples, obtained during wear screening tests, are hsted in Table 10.8 (Heimann and WiUmann, 1998). 

High hardness No plastic deformation under load No elastic deformation under load No aeep Wear resistance over many years 

Finely grained microstrucmre Dense (no porosity) Excellent surface finish, low coefficient of friction 

---