Introduction

We have carried out a 15 year survival analysis of a prospective, randomised trial comparing cemented with cementless fixation of press-fit condylar primary total knee replacements.

Introduction: The National Institute for Clinical Excellence (NICE), in its “Guidance on the Selection of Prostheses for Primary Total Hip Replacement”, states that a revision rate of 10% or less at ten years should be regarded as the “benchmark” in the selection of prostheses for primary Total Hip Replacement (THR). Furthermore, they state that evidence for this, in relation to a particular prosthesis, should relate to data from a number of centres, obtained via adequately sized, well conducted observational studies, preferably with consecutive patients from non selected populations. Aim: This paper presents the results of such a study for primary Charnley THR. Methods: All patients undergoing primary Charnley THR during 1990 where prospectively registered with the Trent Regional Arthroplasty Study (TRAS). During 1990, 1198 Charnley THRs were performed on 1152 patients, under the care of 56 consultants, in 18 national health service and 6 private hospitals. The cohort contains 39.0 % male and 61.0 % female patients, with an average age at operation of 69.1years (21–103 years). At 10 years all surviving patients at 5 years were registered with the ONS to ascertain living patients. These patients were contacted by letter to determine whether or not their THR had been revised. The status of the THR, for non-responding patients, was determined by contacting the patient’s GP through the Contractor Services Agency (CSA). Survival analysis was performed using life table analysis as described by Armitage and Berry and the endpoint was defined as revision surgery to replace an original implant component. Results: At 10 years, the recipients of 246 THRs had died. The recipients of 86 THRs did not respond to the questionnaire at ten years. There was no follow–up data on 42 implants at both 5 and 10 years intervals. Thus, implant status at five or ten years, in living patients was known for 910 of 952 (95.6%) THRs. The ten-year crude revision rate was 43 out of 1198 (3.59%) and cumulative survival rate was 95.4% (95% CI, 93.2% – 96.9%). Conclusion: This is the first study to assess the survivorship at 10 years for primary Charnley THRs performed in the “general setting“ of the NHS as opposed to specialist centres and shows a result well within the NICE benchmark.