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Objective To assess the failure rate of cemented, uncemented, hybrid, and reverse hybrid total hip replacements in patients aged 55 years or older. Design Register study. Setting Nordic Arthroplasty Register Association database (combined data from Sweden, Norway, Denmark, and Finland). Participants 347 899 total hip replacements performed during 1995-2011. Main outcome measures Probability of implant survival (Kaplan-Meier analysis) along with implant survival with revision for any reason as endpoint (Cox multiple regression) adjusted for age, sex, and diagnosis in age groups 55-64, 65-74, and 75 years or older. Results The proportion of total hip replacements using uncemented implants increased rapidly towards the end of the study period. The 10 year survival of cemented implants in patients aged 65 to 74 and 75 or older (93.8%, 95% confidence interval 93.6% to 94.0% and 95.9%, 95.8% to 96.1%, respectively) was higher than that of uncemented (92.9%, 92.3% to 93.4% and 93.0%, 91.8% to 94.0%), hybrid (91.6%, 90.9% to 92.2% and 93.9%, 93.1% to 94.5%), and reverse hybrid (90.7%, 87.3% to 93.2% and 93.2%, 90.7% to 95.1%) implants. The survival of cemented (92.2%, 91.8% to 92.5%) and uncemented (91.8%, 91.3% to 92.2%) implants in patients aged 55 to 64 was similar. During the first six months the risk of revision with cemented implants was lower than with all other types of fixation in all age groups. Conclusion The survival of cemented implants for total hip replacement was higher than that of uncemented implants in patients aged 65 years or older. The increased use of uncemented implants in this age group is not supported by these data. However, because our dataset includes only basic information common to all national registers there is potential for residual confounding.

Background and purpose An earlier Nordic Arthroplasty Register Association (NARA) report on 280,201 total hip replacements (THRs) based on data from 1995-2006, from Sweden, Norway, and Denmark, was published in 2009. The present study assessed THR survival according to country, based on the NARA database with the Finnish data included. Material and methods 438,733 THRs performed during the period 1995-2011 in Sweden, Denmark, Norway, and Finland were included. Kaplan-Meier survival analysis was used to calculate survival probabilities with 95% confidence interval (CI). Cox multiple regression, with adjustment for age, sex, and diagnosis, was used to analyze implant survival with revision for any reason as endpoint. Results The 15-year survival, with any revision as an endpoint, for all THRs was 86% (CI: 85.7-86.9) in Denmark, 88% (CI: 87.6-88.3) in Sweden, 87% (CI: 86.4-87.4) in Norway, and 84% (CI: 82.9-84.1) in Finland. Revision risk for all THRs was less in Sweden than in the 3 other countries during the first 5 years. However, revision risk for uncemented THR was less in Denmark than in Sweden during the sixth (HR = 0.53, CI: 0.34-0.82), seventh (HR = 0.60, CI: 0.37-0.97), and ninth (HR = 0.59, CI: 0.36-0.98) year of follow-up. Interpretation The differences in THR survival rates were considerable, with inferior results in Finland. Brand-level comparison of THRs in Nordic countries will be required.

Background and purpose The risk of revision due to infection after primary total hip arthroplasty (THA) has been reported to be increasing in Norway. We investigated whether this increase is a common feature in the Nordic countries (Denmark, Finland, Norway, and Sweden). Materials and methods The study was based on the Nordic Arthroplasty Register Association (NARA) dataset. 432,168 primary THAs from 1995 to 2009 were included (Denmark: 83,853, Finland 78,106, Norway 88,455, and Sweden 181,754). Adjusted survival analyses were performed using Cox regression models with revision due to infection as the endpoint. The effect of risk factors such as the year of surgery, age, sex, diagnosis, type of prosthesis, and fixation were assessed. Results 2,778 (0.6%) of the primary THAs were revised due to infection. Compared to the period 1995-1999, the relative risk (with 95% CI) of revision due to infection was 1.1 (1.0-1.2) in 2000-2004 and 1.6 (1.4-1.7) in 2005-2009. Adjusted cumulative 5-year revision rates due to infection were 0.46% (0.42-0.50) in 1995-1999, 0.54% (0.50-0.58) in 2000-2004, and 0.71% (0.66-0.76) in 2005-2009. The entire increase in risk of revision due to infection was within 1 year of primary surgery, and most notably in the first 3 months. The risk of revision due to infection increased in all 4 countries. Risk factors for revision due to infection were male sex, hybrid fixation, cement without antibiotics, and THA performed due to inflammatory disease, hip fracture, or femoral head necrosis. None of these risk factors increased in incidence during the study period. Interpretation We found increased relative risk of revision and increased cumulative 5-year revision rates due to infection after primary THA during the period 1995-2009. No change in risk factors in the NARA dataset could explain this increase. We believe that there has been an actual increase in the incidence of prosthetic joint infections after THA.