Primary Uncemented Partly Ti-coated Total Hip Prosthesis With and Without HA, and Alumina-on-alumina Articulation

Both HA coated and certain uncoated femoral stems have good results in general. On the cup side the results are more variable, either with or without HA. HA may delaminate from the prosthesis, damage the articulation, witch may lead to osteolysis and aseptic loosening. The investigators are investigating whether a well working uncemented hip prosthesis design with HA coating, will perform without HA in the long run, when the investigators use pure Ti macrostructure and alumina on alumina articulation. Hypothesis: The bone ingrowth will be equal when the surface has almost equal roughness in Ti and HA version. This means that HA on Ti is not necessary with a well functioning prosthesis design. 0-hypothesis:The two prosthesis perform equal in survival, clinically (HHS),radiographic and in patient satisfaction at 2, 5, 10, 15 and 20 years.