Introduction: As a consequence of the rising prevalence of diabetes worldwide, an increasing proportion of diabetic THR patients may be expected in coming years. Diabetes research on postoperative complications among arthroplasty patients is limited. We evaluated the extent to which diabetes affect the revision rate due to aseptic loosening, deep infection and dislocation following total hip arthroplasty (THA).

Material and Methods: We used the Danish Hip Arthroplasty Registry (DHR) to identify all primary THR patients operated on during the period from 1 January 1996 to 31 December 2005. The presence of diabetes among THA patients was identified by using The Danish National Registry of Patients and The Danish National Drug Prescription Database. We used Poisson regression analyses, to estimate relative risk (RR) and 95% Confidence Interval (CI) for patients with diabetes compared to patients without diabetes, both crude and adjusted for potentially confounding factors.

Results: We identified 57 575 first primary THR patients in DHR, of which 3 278 (5.7%) were with diabetes and 54 297 (94.3%) without diabetes. An adjusted RR for revision due to deep infection of 1.45 (CI: 1.00–2.09) was found for THA diabetic patients compared to patients without diabetes. The RR was particularly high for THA patients with diabetes less than five years (RR was 1.71 (CI: 1.24–32.34), with the presence of diabetes related comorbidites prior THA (RR was 2.35 (CI: 1.39–3.98) and diabetes related complications (RR was 1.88 (CI: 1.17–3.03).

Conclusion. The patient and the surgeon should be aware of the relative increased risk of revision due to deep infection following THA as compared with the risk in THA patients without diabetes.

Introduction: NSAID’s are routinely used as either pain-killer or in prevention of heterotopic bone formation (HBF) after total hip replacement (THR). Experimental animal studies have in two decades shown NSAID’s to influence bone remodelling, and thereby also to reduce fixation and bone healing round non-cemented implants. Clinical studies have, however, non been able to demonstrate these observations, too. This may be due a low power in such studies with only few observations. The present study present results from The Danish Hip Arthroplasty Register (DHR) on the effect of NSAID’s to revision of cemented implants due aseptic loosening.

Materials and Methods: DHR was established January 1, 1995 and covers all Danish clinics. All report both primary and revision cases to a central database. Every Danish citizen have an unique civil register number - making it possible to follow both primary and revision cases and to investigate survival due various circumstances. Cox’s regression analysis to estimate the relative risks (RR) of revision and data are presented with 95% confidence intervals.

Results: During the period 1995–2006 total 64.725 primary THR’s were recorded in DHR. Of these 8.531 cases had prophylactic NSAID after surgery in prevention of HBF. Total 409 hips (4.8%) of this population undergoing revision THR had been treated with NSAID’s after surgery. In contrast, 2.536 (4.3%) undergoing revision in the population had no NSAID’s. Overall the risk for revision for any reason was reduced for patients treated with NSAID’s (RR = 0.88 (0.79–0.98) p=0.02). This was even more significant in revision due to aseptic loosening (RR = 0.76 (0.64–0.90) p< 0.01). Subgroup analysis showed that the reduction was in the cemented THR (RR = 0.82 (0.70–0.95) p=0.01) with a further more significant sign in revision due aseptic loosening (RR = 0.69 (0.55–0.87) p< 0.01). In contrast there was no differences in cementless THR neither in revision for any reason (RR = 1.19 (0.86–1.63) p=0.30) nor for aseptic loosening (RR = 1.72 (0.87–3.43) p=0.12).

Discussion and Conclusion: The present investigation from the DHR is a good example of what can be evaluated from a register, and never possibly concluded from standard clinical studies. The results demonstrate that NSAID’s administrated in order to prevent HBF after primary THR surprisingly did not increase the risk of revision in non-cemented implants, but in contrast did reduce the risk for revision in cemented THR. The reason for this reduction is speculated, and be relate to the phenomenon that NSAID’s did not only influence the osteoblastic activity, but also the osteoclasts and thereby prevent early postoperative bone degradation after cemented THR where heat from the bone-cement may impose devascu-larisation of vital bone near the implant.

Introduction: We examined the risk of blood transfusion in patients undergoing THA at 21 different orthopaedic departments in Denmark.

Material and Methods: Patients with primary THA (n=21,773) registered in the Danish Hip Arthroplasty Registry between 1999 and 2006 were identified. Data on use of blood transfusion was collected from the Danish Transfusion Data Base (DTDB). The outcome was defined as red blood cell transfusion (yes/no) within 7 days after surgery. Modified Poisson regression analyses were used to estimate the risk of red blood cells transfusion (RR) and a 95% confidence interval (CI) adjusting for possible confounding factors including patient related factors (age, gender, comorbidity and diagnosis for primary THA) and surgery related factors (type of anestesia, type of osiffication prophylaxis type of operation, duration of surgery, and duration of admission. The risk of blood transfusion for each department was compared with the general risk of blood transfusion for all departments.

Results: Overall, red blood cells transfusion was given to 8,162 of 21,773 patients (37%) (range between 16% and 64%, depending on department). After adjusting for different patient–and surgery-related factors, the adjusted RRs differed from 1.24 (95% CI, 2.07–3.43) to 0.52 (95% CI, 0.4–0.69) using all departments as reference. Coefficient of variation was 23%.

Conclusions: Substantial differences in the risk of red blood cells transfusion among THA patients were found when comparing a sample of Danish orthopaedic departments. The differences in use of transfusions appeared not to be explained by a range of patient – and surgery – related factors and may thus reflect true differences in transfusion practice.

Background: Intraoperative femoral fracture is a well-known complication to primary total hip arthroplasty (THA). Experimental studies have suggested that intraoperative fractures may affect implant survival. How-ever, available clinical data are sparse.

Methods: We used data from the Danish Hip Arthroplasty Registry to identify patients treated with a primary THA due to primary osteoarthritis in Denmark between 1995 and 2005 (n=39478). Data was linked to two national Danish databases to conduct time dependent implant survival analyses. Implant survival and relative risk estimates were calculated for patients treated conservatively and patients treated with osteosynthesis after sustaining intraoperative femoral fractures during THA surgery. The reference group was THA’s performed without sustaining intraoperative femoral fracture. Furthermore we assessed the relative risk for reoperations and readmission to an orthopaedic department 3 months postoperatively.

Results: 282 patients (0.7%) were treated conservatively due to intraoperative femoral fracture and 237 patients (0.6%) were treated with osteosynthesis. The Kaplan– Meier survival plots revealed a significant poorer THA survival after osteosynthesis of intraoperative femoral fractures. In the 0–6 months postoperative period the adjusted relative risk (RR) for revision was 1.5 (95% CI: 1.1–1.7) for patients treated conservatively. In the same period the adjusted RR for revision was 5.7 (3.3–10.0) for patients treated with osteosynthesis. In the period 6 months to 11 years postoperatively we did not find any significant differences in the RR for revision among the groups.

Interpretation: Intraoperative fractures increase the relative risk for revision the first 6 postoperative months. Therefore, patients should be informed about the risk for revision when sustaining an intraoperative femoral fracture. Further, initiatives aimed at reducing the risk of revision in the first 6 months following THA should be considered in patients with intraoperative fractures including immediate revision of the stem to a larger stem with distal fixation and restricted weight bearing.

Introduction: We studied the survival of primary total hip arthroplasty (THA) in patients undergoing surgery because of rheumatoid arthritis (RA) and compared our results to the survival of primary THA in patients undergoing surgery because of osteoarthritis (OA). Furthermore, we evaluated the effect of primary THA-survival in RA-patients concerning multiple confounders such as age, gender, comorbidity, and cemented/uncemented prosthesis.

Material and Methods: Using the Danish Hip Arthroplasty Register we gathered info concerning 1.302 primary THA’s in 1.106 RA-patients and 41.848 primary THA’s in 35.729 OA-patients. These patients underwent surgery from 1995 to 2004. Using the Cox regression model we estimated the relative risk (RR) for revision due to aseptic loosening, other reasons, and all reasons and adjusted for above mentioned confounders.

Results: The adjusted RR’s for cup-revision of primary THA’s in patients with RA (compared to OA) were 1.22 (aseptic loosening − 95% Confidence Interval (CI) 0.75–1.99), 0.90 (other causes for revision − 95% CI 0.61–1.32), and 1.00 (all revisions − 95% CI 0.74–1.35). For the stem the RR’s were 0.50 (aseptic loosening − 95% CI 0.25–0.99), 0.58 (other causes for revision − 95% CI 0.35–0.95), and 0.54 (all revisions − 95% CI 0.36–0.80). RR for all revisions (both cup and stem) was 0.83 (95% CI 0.64–1.09). The RAsubanalysis showed an increased RR (all revisions) for men compared to women (RR 2.60; 95% CI 1.19–5.66). No significant result concerning all revisions for age, comorbidity, and cemented/ uncemented prosthesis was found. The mean follow-up was 5,4 years for RA and 4,8 years for OA.

Conclusion: The survival of primary THA’s in RA could not be associated with any clearly overall increased risk of revision when compared to OA. However, male gender seems to be a risk factor for undergoing revision-THA in the RA-subgroup.

Aim: We determined 90 days mortality following primary total hip replacement (THR) and examined the impact of age and level of comorbidity.

Methods: We used data from the nationwide population based Danish Hip Arthroplasty Registry between 1 January 1995 and 31 December 2004. Each THR patient was matched according to gender and age on the time of surgery with 3 persons from the general population randomly sampled using the Danish Civil Registration system, resulting in a total of 44 818 THA patients and 120 883 controls. We used a Cox regression analyses to computed age and comorbidity specific mortality rates (MR) and mortality rate ratio (MRR) with 95% Confidence Intervals (CI) for THR patients compared with the general population, as well as Number Needed to Harm (NNH).

Results: The MRs for THR patients relative to those for the general population were highest in the patients younger than 60 years, corresponding to an adjusted MRR of 3.6 (95% CI: 2.2–5.5). Similar, an adjusted MRR was 1.2 (95% CI: 1.0–1.4) in patients aged 80 years and over. The THR patients younger than 60 years had more comorbidity than the controls, whereas distribution of comorbidity was equal in all other age groups. MRRs increase with comorbidity level for both THR patients and controls in all age groups. MRR for THR patients vs. controls within high comorbidity level aged below 60 years and aged 80 years and over was 3.5 (1.3–9.8) and 0.7 (0.5–0.9), respectively. However, hospitalisation with particularly cardio–og cerebrovasculaar disease before surgery increase mortality risk for both age groups, whereas hospitalisation with cancer increase mortality risk for patients younger than 60 years and decrease it for patients aged 80 years and over.

Conclusions: Overall mortality of THR patients relative to those in the general population was higher 90 days after surgery. Our findings apply particularly for THR patients aged 10 to 59 and 80 years and over. Although THR patients aged 80 years and over with high comorbidity level had lower mortality than corresponding persons from the general population, some particular groups of medical condition prior to surgery is associated with increased mortality risk whereas other medical conditions are associated with decreased mortality risk. We should be careful in making clinical decisions based on the Charslon comorbidity index; subgroups analyses may be necessary.

Further, we will present data on 90 days cause of death following primary THR and predictors for death, including age, gender and comorbidity (analyses are not finished yet).