[Criteria for evaluating hip joint arthroplasty].

Development and state of the art of the Total Hip Replacement (THR) are reviewed. Progress since the introduction of the "low friction arthroplasty" by John Charnley/UK over 40 years ago consists first of all in an impressive reduction of the number and severity of complications: infection, failures of materials, thromboembolism and aseptic loosening. Current 10 year survival rates should not be lower than 97%. This high standard of THR performance has become the greatest obstacle to further progress. The most important factors for the assessment and the outcome of a THR are the operative (cementing) technique, the mechanical design of the prosthesis, the characteristics of the surfaces (implant, bone cement, bone) and the materials used. A prognosis of the survival of a THR can be made based on negative subjective clinical and negative objective criteria. On X-ray films these criteria are shown first of all as changes (radiolucency, osteolysis, progressive migration) at the implant-bone interface and within the periprosthetic bone itself.