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.

Background and purpose Over the decades, improvements in surgery and perioperative routines have reduced the incidence of deep infections after total hip arthroplasty (THA). There is, however, some evidence to suggest that the incidence of infection is increasing again. We assessed the risk of revision due to deep infection for primary THAs reported to the Norwegian Arthroplasty Register (NAR) over the period 1987–2007.Method We included all primary cemented and uncemented THAs reported to the NAR from September 15, 1987 to January 1, 2008 and performed adjusted Cox regression analyses with the first revision due to deep infection as endpoint. Changes in revision rate as a function of the year of operation were investigated.Results Of the 97,344 primary THAs that met the inclusion criteria, 614 THAs had been revised due to deep infection (5-year survival 99.46%). Risk of revision due to deep infection increased throughout the period studied. Compared to the THAs implanted in 1987–1992, the risk of revision due to infection was 1.3 times higher (95%CI: 1.0–1.7) for those implanted in 1993–1997, 1.5 times (95% CI: 1.2–2.0) for those implanted in 1998–2002, and 3.0 times (95% CI: 2.2–4.0) for those implanted in 2003–2007. The most pronounced increase in risk of being revised due to deep infection was for the subgroup of uncemented THAs from 2003–2007, which had an increase of 5 times (95% CI: 2.6–11) compared to uncemented THAs from 1987–1992.Interpretation The incidence of deep infection after THA increased during the period 1987–2007. Concomitant changes in confounding factors, however, complicate the interpretation of the results.

Objective. To compare differences in the risk of revision for infection and changes in risk over time and in time from primary surgery to revision for infection after total hip replacement (THR) and total knee replacement (TKR) in rheumatoid arthritis (RA) and osteoarthritis (OA) patients. Methods. In the Norwegian Arthroplasty Register, 6,629 and 102,157 primary total joint replacements in patients with RA and OA, respectively, were identified from 1987 (1994 for knees) until 2008. Survival analyses with revision due to infection as the end point were performed using Kaplan-Meier methods for constructing survival curves and multiple Cox regression to calculate relative risk (RR) estimates for diagnosis, age, sex, and year of primary surgery. An extended Cox model was used to estimate RR within different followup intervals. Results. RA patients with TKR had a 1.6 times higher risk of revision for infection than OA patients, whereas there was no difference in the THRs. In the THRs, we found a higher risk of revision for infection from 2001 onward, whereas the development for TKRs was the opposite. These time effects affected the RA and OA groups equally. The risk of revision for infection from 6 years postoperatively on was higher in RA patients. Conclusion. The overall risk of revision for infection after TKR was higher in RA patients. The risk of late infection leading to revision of the TKR and THR was higher in RA patients than in OA patients. After the year 2000, the RR of revision for infection in RA compared with OA remained unchanged.

Using data from the Norwegian Hip Fracture Register, 8639 cemented and 2477 uncemented primary hemiarthroplasties for displaced fractures of the femoral neck in patients aged > 70 years were included in a prospective observational study. A total of 218 re-operations were performed after cemented and 128 after uncemented procedures. Survival of the hemiarthroplasties was calculated using the Kaplan-Meier method and hazard rate ratios (HRR) for revision were calculated using Cox regression analyses. At five years the implant survival was 97% (95% confidence interval (CI) 97 to 97) for cemented and 91% (95% CI 87 to 94) for uncemented hemiarthroplasties. Uncemented hemiarthroplasties had a 2.1 times increased risk of revision compared with cemented prostheses (95% confidence interval 1.7 to 2.6, p < 0.001). The increased risk was mainly caused by revisions for peri-prosthetic fracture (HRR = 17), aseptic loosening (HRR = 17), haematoma formation (HRR = 5.3), superficial infection (HRR = 4.6) and dislocation (HRR = 1.8). More intra-operative complications, including intra-operative death, were reported for the cemented hemiarthroplasties. However, in a time-dependent analysis, the HRR for re-operation in both groups increased as follow-up increased. This study showed that the risk for revision was higher for uncemented than for cemented hemiarthroplasties.

Primary uncemented femoral stems reported to the Norwegian arthroplasty register between 1987 and 2005 were included in this prospective observational study. There were 11 516 hips (9679 patients) and 14 different designs of stem. Kaplan-Meier survival probabilities and Cox regression were used to analyse the data. With aseptic loosening as the end-point, all currently used designs performed excellently with survival of 96% to 100% at ten years. With the end-point as stem revision for any cause, the long-term results of the different designs varied from poor to excellent, with survival at 15 years ranging between 29% and 97%. Follow-up for longer than seven years was needed to identify some of the poorly-performing designs. There were differences between the stems; the Corail, used in 5456 hips, was the most frequently used stem with a survival of 97% at 15 years. Male gender was associated with an increased risk of revision of x 1.3 (95% confidence interval 1.05 to 1.52), but age and diagnosis had no influence on the results. Overall, modern uncemented femoral stems performed well. Moderate differences in survival between well-performing stems should be interpreted with caution since the differences may be caused by factors other than the stem itself.