Background: Annually about 9,000 patients in Norway are operated because of hip fractures. From January 2005 all these fractures should be reported to The Norwegian Hip Fracture Register, founded by the Norwegian Orthopaedic Association and operated by The Norwegian Arthroplasty Register from 1. January 2005.

Patients and methods: We have established contacts at every hospital in Norway that perform surgery for hip fractures. Immediately after the surgery the surgeon fills in a standardized form which is sent to the register once a month. On the form there are both patient- and procedure-related questions. Four and twelve months postoperatively we send a questionnaire to the patients, including the Norwegian translation of the EuroQol-5D. Patient information is linked to the Norwegian Death Register using the unique identification number assigned for each resident of Norway. We have so far included 5,668 primary hip fractures operations and 607 revision procedures including revisions to hemiprosthesis and total hip replacements (THR).

Results: After 1 year of registration 100 % of the hospitals are reporting to the register. Approximately 50 % of the patients have answered the questionnaire. Of the primary operated patients the mean age was 80.5 years and 73 % were females. 59 % of the fractures were intracapsular femoral neck fractures and approximately 2/3 of those were dislocated. 35 % of the fractures were intertrochanteric or subtrochanteric.

Intracapsular dislocated fractures: Screw fixation was used in 48 % of the hips while 46 % of the hips were operated with a hemiarthroplasty, and 4.1 % were operated with a THR. We could not find any difference in mortality between screw fixated patients and patients operated with a hemiarthroplasty.

Intertrochanteric/subtrochanteric fractures: The hip compression screw osteosynthesis was used in 88 % of the patients, 6.3 % of these had a lateral support plate. An intramedullary nail was used in 8.9 % of the patients.

Conclusion: After only one year, the reports from the surgeons were good. Taking the age and general status into consideration, also the response from the patients is satisfactory. With longer follow-up we will be able to give more information on the outcomes of hip fractures and of the different treatment. Updated analysis will be reported.

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 × 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.

We analysed the results of different strategies in the revision of primary uncemented acetabular components reported to the Norwegian Arthroplasty Register. The aim was to compare the risk of further acetabular revision after isolated liner exchange and complete component revision. The results of exchanging well-fixed components were also compared with those of exchanging loose acetabular components. The period studied was between September 1987 and April 2005. The following groups were compared: group 1, exchange of liner only in 318 hips; group 2, exchange of well-fixed components in 398; and group 3, exchange of loose components in 933. We found that the risk of a further cup revision was lower after revision of well-fixed components (relative risk from a Cox model (RR) = 0.56, 95% confidence interval 0.37% to 0.87%) and loose components (RR = 0.56, 95% confidence interval 0.39% to 0.80%), compared with exchange of the liner in isolation. The most frequent reason for a further acetabular revision was dislocation, accounting for 61 (28%) of the re-revisions. Other reasons for further revision included pain in 27 (12%), loosening in 24 (11%) and infection in 20 (9%). Re-revisions because of pain were less frequent when complete component (fixed or loose) revision was undertaken compared with isolated exchange of the liner (RR = 0.20 (95% confidence interval 0.06% to 0.65%) and RR = 0.10 (95% confidence interval 0.03% to 0.30%), respectively). The risk of further acetabular revision for infection, however, did not differ between the groups.

In this study, exchange of the liner only had a higher risk of further cup revision than revision of the complete acetabular component. Our results suggest that the threshold for revising well-fixed components in the case of liner wear and osteolysis should be lowered.

We performed a randomised, radiostereometric study comparing two different bone cements, one of which has been sparsely clinically documented. Randomisation of 60 total hip replacements (57 patients) into two groups of 30 was undertaken. All the patients were operated on using a cemented Charnley total hip replacement, the only difference between groups being the bone cement used to secure the femoral component. The two cements used were Palamed G and Palacos R with gentamicin. The patients were followed up with repeated clinical and radiostereometric examinations for two years to assess the micromovement of the femoral component and the clinical outcome.

The mean subsidence was 0.18 mm and 0.21 mm, and the mean internal rotation was 1.7° and 2.0° at two years for the Palamed G and Palacos R with gentamicin bone cements, respectively. We found no statistically significant differences between the groups. Micromovement occurred between the femoral component and the cement, while the cement mantle was stable inside the bone. The Harris hip score improved from a mean of 38 points (14 to 54) and 36 (10 to 57) pre-operatively to a mean of 92 (77 to 100) and 91 (63 to 100) at two years in the Palamed G and Palacos R groups, respectively. No differences were found between the groups.

Both bone cements provided good initial fixation of the femoral component and good clinical results at two years.

Purpose: About 1% of the children are born with neonatal hip instability (NHI). By combining data from the Medical Birth Registry of Norway (MBRN) with that of the Norwegian Arthroplasty Register (NAR), the influence of NHI on the risk for total hip arthroplasty (THA) before 37 years of age are studied.

Materials and Methods: Since 1967 medical data, included stability of the hips, on all new-borns in Norway (2 092 536 babies) have been compiled. Since 1979 all THA performed in Norway are reported to the NAR. Until 2004 85,120 primary THAs were registered, of these 492 were performed on patients under 37 years of age. These two national registries were linked by using the unique person identification number assigned to each inhabitant of Norway.

Results: Of those 20 668 born with NHI (1%), 9 had received a THA before 37 years of age (43/100 000). Since only 18 of 100 000 new-borns without NHI had had THA, new-borns with NHI had 2,5 times increased risk for having a THA before they become 37 years.

Of the 492 THA in patients younger than 37 years in the NAR, 101 THA (20.5%) were, according to the surgeon, operated because of developmental dysplasia of hip (DDH). Since 13 of these were bilateral THA, the number of patients were 88. Only 9 of these 88 DDH-patients were, however, reported to have NHI. This is surprisingly few, since their dysplasia should be anticipated to be rather severe. Does this indicate that the hip-screening for new-borns in Norway should be changed?

Conclusions: New-borns with NHI has 2.5 times increased risk for THA before the age of 37 years compared to those with stable hips at birth. The absolute risk is, however, low, only 43/100 000. Of those 88 who received THA because of DDH before 37 years, 79 had, however, reported normal hips at birth.

Background: This study was done to compare the early failure of primary cemented unicompartmental knee arthroplasties (UKA) with that of total knee arthroplasties (TKA).

Methods: The Kaplan-Meier survial-method and the Cox multiple regression model were used to compare the failure rates of the primary cemented UKAs (n=1410) and the primary cemented TKAs (patellar resurfaced) (n=2818) that were reported to the Norwegian Arthroplasty Register between 1st January 1994 and 1st April 2003.

Results: 8 years survival for UKAs was 85.2 % (95% CI: 81.5–88.9) compared to 93.0 % (91.5–94.5) for TKAs, relative revision risk (RR) 1.8 (1.4–2.4), p< 0.001. The increased revision risk in UKAs was seen in all age categories. Among the UKAs the 8 years survival showed no statistically significant difference for MOD III, Genesis uni and Oxford II. However, Duracon uni knees had, statistically significantly higher rates of revision, although the numbers of prostheses were low. Two UKAs were introduced recently and the follow up was short. After 3 years the Miller Galante uni had 82.8 % (75.6–90.0) survival compared to 93.8 (91.0–96.6) for the Oxford III knee, p< 0.002. The higher failure rates of the Miller Galante and Duracon knees were mainly due to more loosening of the tibial components. UKAs had an increased risk of revision due to pain, aseptic loosening of the tibial and femoral components and periprosthetic fractures compared to TKAs. The UKAs had a lower risk of infection compared to TKAs.

Conclusions: This prospective study has shown that the prostheses survival of cemented UKAs was not as good as for cemented TKAs. There were differences between the UKAs, but the best UKA had results inferior to the average of the TKAs.

Materials and methods: Based on data from the Norwegian Arthroplasty Register, we reviewed the results of uncemented femoral stems in Norway in the period 1987 to 1. April 2002. We compared these results to the results of the cemented Charnley monoblock stem, which still is the most commonly used femoral stem in Norway. Only prostheses used in more than one hundred hips were included. Based on these criteria, we identified a total of 7 856 primary total hip prostheses in fifteen different uncemented stems. With the Kaplan-Meier method, the survival of the primary prostheses were calculated and compared with each other and with the Charnley stem. The endpoint was revision in which the whole prostheses or the stem alone was removed or exchanged. The Cox regression analysis was used to adjust for differences in age, gender, diagnosis, former operations and profylactic antibiotics. Separate analyses for patients younger than 60 years and for stems with follow-up less than ten years were done. Reasons for revision in the uncemented Corail stem and the cemented Charnley stem was analysed.

Results: The Corail stem, wich is the most commonly used uncemented stem in Norway (n=3590), had excellent long term results. 10 years survival in patients younger than 60 years was for the Corail 97,5% and for the Charnley 90,2% (p=0,001). Reasons for revision of the Corail were in most cases pain and repeated dislocations. Aseptic loosening was the dominant cause of failure of the Charnley stem. Several uncemented stems have results which are as good as or superior to the Charnley. The Femora, the Biofit, the Parhofer and the Harris Galante stems all had inferior results. Many uncemented stems with less than 10-years of follow-up have excellent 5 years survival.

The 10 years survival of uncemented total hip arthroplasties, however was inferior to the all-cemented Charnley. Cup revisions due to aseptic loosening, and wear and/or osteolysis were the reasons for this.

Discussion: The Corail stem has excellent long term results. Several newer stems have promising short- and medium term results. Due to inferior results of unce-mented cups, however, most Norwegian orthopaedic surgeons use cemented primary hip replacements.

Aims: To assess the influence of hip disease on the risk of revision, we studied different disease groups among 53 698 primary total hip replacements (THRs) reported to the NAR between 1987 and 1999. Methods: the revision rate in the 8 most common hip diseases were compared by kaplan-meier survival analyses and cox multiple-regression. To eliminate the influence of prosthesis type a subgroup of 16217 charnley prostheses were analysed. Results: we found statistically significant differences in prosthesis survival among the hip diseases, but after adjustment for prosthesis type most of the differences disappeared. In patients ≤60 years, 59% of the prostheses were uncemented and 33% could be defined as inferior uncemented prostheses. In the charnley subgroup only complications after fracture of the femoral neck had an increased risk for revision compared to primary osteoarthritis (rr 1.5, p=0.005). 10 years survival for cemented charnley prostheses with osteoarthritis was 92.0% for patients ≤60 years and 93.5% for patients > 60 years. Conclusions: after adjustment the results for all disease groups were good. The results of thrs in disease-groups where patients are operated on at a young age were less good because these patients had often been given inferior uncemented prostheses.

Aims: The mid- and long-term results of uncemented cups are uncertain. The aim of this study was to assess their results and to compare them with the most common cemented cup, the Charnley. Material and methods: In the study we included only patients under the age of 60 that had been operated with one of the 10 most common uncemented cup brands or the Charnley cup. Only brands that had been in use for at least 6 years were included. There were only minor differences among the brands concerning age, gender and diagnosis. Survival percentages were calculated with the Kaplan-Meier method. Results: With all cup revisions (change of cup or polyethylene liner) as end-point, the overall 5 year survival probability was 97% (95% CI: 96.3 97.3) which decreased to 86% (95% CI: 84.4 Ð 87.5) at 10 years. The 10 years survival varied from 74% for the Atoll cup to 88% for the Optiþx and the Harris-Galante cup, whereas for the cemented Charnley cup the 10 years survival probability was 94%. For the uncemented cups the increase in revision risk after 6 years was mainly due to wear and osteolysis. For the HA-coated cups also aseptic loosening increased after 6 years of follow-up. Conclusion: Uncemented cups in young patients had good short-term results. At 10 years of follow-up for the investigated uncemented cup brands, the results were inferior to the Charnley cup.

Purpose: The outcome of primary total hip arthroplasty (THA) after a previous paediatric hip disease was studied in data from the Norwegian Arthroplasty Register (NAR).

Materials and Methods: 72,301 primary THAs were reported to the NAR for the period 1987 – February 2002. Of these, 5,459 (7.6%) were performed because of sequela after developmental dysplasia of hip (DDH), 737 (1.0%) because of DDH with dislocation, 961 (1.3%) because of Perthes’/ slipped femoral capital epiphysis (SFCE) and 50,369 (70%) because of primary osteoarthritis (OA). Prosthesis survival was calculated by the Kaplan-Meier method and relative risks for revision in a Cox model with adjustments for age, gender, type of systemic antibiotic, operation time, type of operating theatre and brand of prosthesis.

Results: Without any adjustments the THAs for all three groups of paediatric hip diseases had 1.4 – 2.0 times increased risk for revision compared to that of OA (p< 0.001). Due to huge differences in the studied groups, a more homogenous subset of the data had to be analysed. In this subset, only THAs with well documented prostheses, high-viscosity cements and antibiotic prophylaxis both systemically and in the cement were included (16,874 THAs). In this homogenous subset, no differences in the survivals could be detected for DDH without dislocation and for Perthes’/SFCE compared to OA. For DDH with dislocation the revision risk with all reasons for revisions as endpoint in the analyses was increased 3.3 times compared to OA (p< 0.001), 2.7 times with aseptic loosening as endpoint (p< 0.01) and 10 times with infection as endpoint (p< 0.001).

Conclusions: If well-documented THAs are used after paediatric hip diseases the results are just as good as after osteoarthritis, except for DDH with dislocation where increased revision risk is found.

Using data from the Norwegian Arthroplasty Register, we have the assessed survival of 17 323 primary Charnley hip prostheses in patients with osteoarthritis based upon the type of cement used for the fixation of the implant.

Overall, 9.2% had been revised after follow-up for ten years; 71% of the failures involved aseptic loosening of the femoral component. We observed significantly increased rates of failure for prostheses inserted with CMW1 and CMW3 cements. Using implants fixed with gentamicin-containing Palacos cement as the reference, the adjusted Cox regression failure rate ratios were 1.1 (95% CI 0.9 to 1.4) for implants cemented with plain Palacos, 1.1 (95% CI 0.7 to 1.6) for Simplex, 2.1 (95% 1.5 to 2.9) for gentamicin-containing CMW1, 2.0 (95% CI 1.6 to 2.4) for plain CMW1 and 3.0 (95% CI 2.3 to 3.9) for implants fixed with CMW3 cement. The adjusted failure rate at ten years varied from 5.9% for implants fixed with gentamicin-containing Palacos to 17% for those fixed with CMW3.

We studied the rates of revision for 53 698 primary total hip replacements (THRs) in nine different groups of disease. Factors which have previously been shown to be associated with increased risk of revision, such as male gender, young age, or certain types of uncemented prosthesis, showed important differences between the diagnostic groups. Without adjustment for these factors we observed an increased risk of revision in patients with paediatric hip diseases and in a small heterogeneous ‘other’ group, compared with patients with primary osteoarthritis. Most differences were reduced or disappeared when an adjustment for the prognostic factors was made. After adjustment, an increased relative risk (RR) of revision compared with primary osteoarthritis was seen in hips with complications after fracture of the femoral neck (RR = 1.3, p = 0.0005), in hips with congenital dislocation (RR = 1.3, p = 0.03), and in the heterogenous ‘other’ group. The analyses were also undertaken in a more homogenous subgroup of 16 217 patients which had a Charnley prosthesis implanted with high-viscosity cement. The only difference in this group was an increased risk for revision in patients who had undergone THR for complications after fracture of the femoral neck (RR = 1.5, p = 0.0005).

THR for diagnoses seen mainly among young patients had a good prognosis, but they had more often received inferior uncemented implants. If a cemented Charnley prosthesis is used, the type of disease leading to THR seems in most cases to have only a minor influence on the survival of the prosthesis.