Temporal trends in primary total hip and knee arthroplasty surgery: results from a UK regional joint register, 1991-2004.

INTRODUCTION: The aim of this study was to evaluate temporal trends in the prevalence of primary total hip and knee replacements (THRs and TKRs) throughout the Trent region from 1991 to 2004.

PATIENTS AND METHODS: The Trent Regional Arthroplasty Study records details of primary THR and TKR prospectively and data from the register were examined. Age and gender population data were provided by the Office for National Statistics.

RESULTS: A total of 26,281 THRs and 23,606 TKRs were recorded during this period. Analysis showed that females had an increased incidence rate ratio (IRR) for both primary THR (IRR = 1.29; 95% CI 1.26-1.33; P < 0.001) and TKR (IRR = 1.17; 95% CI 1.14-1.20; P < 0.001). Patients aged 74-85 years had the largest IRR for both primary THR (IRR = 6.7; 95% CI 6.4-7.0; P < 0.001) and TKR (IRR = 15.3; 95% CI 14.4-16.3; P < 0.001).

CONCLUSIONS: The prevalence of primary TKR increased significantly over time whereas THR remained steady in the Trent region between 1991 and 2004.