A large number of articles were identified covering different aspects of hip replacement surgery, few of which were prospective studies that compared different prostheses. Only 9% of the articles included represent randomised clinical studies while 16% are comparative studies, including register studie from Norway and Sweden. Articles describing results for a particular type of prosthesis comprised 75% of all scientific documentation. Included studies differed with respect to patient composition (prognostic factors), sample size and duration of observation.
The evidence-base for the report is therefore unsuitable for the estimation of an overall revision or survival percent for the different type of prostheses or for a quantitative analysis. The assessment bases itself on a qualitative comparison of results.
Results presented in the majority of studies were based on clinical and radiographic assessments of the patients (expressed as revision percent or survival percent of the implanted prosthesis). In the assessment presented here, prostheses are compared based on predefined parameters with respect to the length of follow-up. These results illustrate the following:
- Approximately 1/3 of the prostheses used in Norway in the year 2000 lacked scientific documentation. - There are six cemented prostheses (Charnley, Exeter, ITH, Lubinus, Spectron and Titan) with a documented 90% survival after at least 10 years of follow-up - The Charnley prosthesis together with Lubinus were the only prostheses with over 15 years documented follow-up. - Four cementless femur stems (Bicontact, Bimetric, Omnifit and Zweymller) show good results with follow-up documented within 12.5 years. Mean follow-up duration for these cementless femur prostheses was, however, less than 10 years. - None of the cementless cups used in Norway was supported by documented survival data of more than 10 years duration in 2000. - None of the cementless total prostheses that were in use in 2000 thereby met the criteria of 90% or greater documented survival after 10 years. - The type of cement used has an effect on the survival of the prosthesis according to results from the Norwegian - Swedish prosthetic registers. Results from the register studies indicate that Palacos and Simplex cement are better then CMW and Sulfix cement.
