There is an ongoing discussion on what bearing surfaces to use in different age groups of total hip replacement patients.

We report results from uncemented total hip arthroplasty using ceramic on ceramic bearings reported to the Norwegian Arthroplasty Register in the period 1997–2014.

Kaplan Meier and Cox regression analysis adjusting for age, gender and diagnosis was used to assess prosthesis survival at 10 and 15 years after primary operation and to report relative risk of revision. Endpoint was any revision. Comparison with the cemented Charnley prosthesis (n=17180), with metal-on-polyethylene articulations from the same time period was done. Results in age groups <55, 55–64, 65–74, >=75 were investigated.

The following femur/cup combinations were used; Filler/Igloo (n=2590), Corail/Pinnacle (n=783), Corail/Duraloc (n=467), SCP Unique/Trilogy (n=363), Polar/R3 (n=253), ABGII/ABGII (n=131), other combinations (n=339). Alumina bearing was used in 3807 hips and Alumina-Zirconium composite bearings in 1119 hips. The overall ten and fifteen years unadjusted Kaplan Meier survivals were 94.8 % and 92.0 % respectively with no statistically significant difference between the brands. The cemented Charnley hip arthroplasty had 93.6 % survival at 15 years, and was not statistically significant different from the uncemented ceramic/ceramic group. The 10 years survival in the age groups <55, 55–64, 65–74, >=75 for the uncemented ceramic/ceramic group was 93.7%, 95.3%, 96.0% and 95.4% respectively with no difference between the uncemented brands and the cemented Charnley prosthesis. We found less revisions in patients >=75 in the Charnley group. In the ceramic on ceramic group 11 head fractures and 3 liner fractures were reported.

The 15 years result of uncemented hip replacement with ceramic on ceramic bearing was good, and not different from the Charnley cemented arthroplasty in the age groups <75 years.

We evaluated the rates of survival and cause of revision of seven different brands of cemented primary total knee replacement (TKR) in the Norwegian Arthroplasty Register during the years 1994 to 2009. Revision for any cause, including resurfacing of the patella, was the primary endpoint. Specific causes of revision were secondary outcomes.

Three posterior cruciate-retaining (PCR) fixed modular-bearing TKRs, two fixed non-modular bearing PCR TKRs and two mobile-bearing posterior cruciate-sacrificing TKRs were investigated in a total of 17 782 primary TKRs. The median follow-up for the implants ranged from 1.8 to 6.9 years. Kaplan-Meier 10-year survival ranged from 89.5% to 95.3%. Cox’s relative risk (RR) was calculated relative to the fixed modular-bearing Profix knee (the most frequently used TKR in Norway), and ranged from 1.1 to 2.6. The risk of revision for aseptic tibial loosening was higher in the mobile-bearing LCS Classic (RR 6.8 (95% confidence interval (CI) 3.8 to 12.1)), the LCS Complete (RR 7.7 (95% CI 4.1 to 14.4)), the fixed modular-bearing Duracon (RR 4.5 (95% CI 1.8 to 11.1)) and the fixed non-modular bearing AGC Universal TKR (RR 2.5 (95% CI 1.3 to 5.1)), compared with the Profix. These implants (except AGC Universal) also had an increased risk of revision for femoral loosening (RR 2.3 (95% CI 1.1 to 4.8), RR 3.7 (95% CI 1.6 to 8.9), and RR 3.4 (95% CI 1.1 to 11.0), respectively). These results suggest that aseptic loosening is related to design in TKR.

Cite this article: Bone Joint J 2013;95-B:636–42.

Background

Systematic reviews disagree, but some recent studies have shown better function and less pain after operation with bipolar hemiarthroplasty compared to fixation by two screws in elderly patients operated for displaced femoral neck fractures. There is still uncertainty regarding the mortality associated with both procedures.

Background

A well conducted randomised study found similar functional results for patients with displaced femoral neck fracture comparing operation with a modern uncemented bipolar hemiarthroplasty with a cemented bipolar hemiarthroplasty. The mortality associated with the two procedures has not been sufficiently investigated.

Background

Improving positioning and alignment by the use of computer assisted surgery (CAS) might improve longevity and function in total knee replacements. This study evaluates the short term results of computer navigated knee replacements based on data from a national register.

Background

There are few studies of total knee replacements with cemented tibia and uncemented femur (hybrid). Previous studies have not shown any difference in revision rate between different fixation methods, but these studies had few hybrid prostheses. This study evaluates the results of hybrid knee replacements based on data from the Norwegian Arthroplasty Register (NAR).

Background: In the Norwegian Arthroplasty Register several uncemented femoral stems have proved good or excellent survivorship. The overall results of uncemented total hip arthroplasty however, have been disappointing due to inferior results of the metal backed acetabular cups. In this study we investigated the medium-term performance of primary uncemented metal backed acetabular cups exclusively.

Methods: 9 113 primary uncemented acetabular cups in 7 937 patients operated in the period 1987–2007 were included in a prospective, population-based observational study. All were modular, metal-backed uncemented cups with ultra-high molecular weight polyethylene liners and femoral heads made of steel, cobalt chrome, or Alumina ceramics. Thus 7 different cup designs were evaluated with the Kaplan-Meier method and Cox regression analyses.

Results: Most cups performed well up to 7 years. When the end-point was cup revision due to aseptic cup loosening, the cups had a survival of 87 to 100% at 10 years. However, when the end-point was cup revision of any reason, the survival estimates were 81 to 92% for the same cups at 10 years. Aseptic loosening, wear, osteolysis and dislocation were the main reasons for the relatively poor overall performance of the metal backed cups in this study. Prostheses with Alumina heads performed slightly better than those with steel- or cobalt chrome in sub-groups.

Conclusions: Whereas most cups performed well at 7 years, the survivorship declined with longer follow-up time. Fixation was generally good. None of the metal-backed uncemented acetabular cups with UHMWPE liners investigated in the present study had satisfactory long-term results due to high rates of wear, osteolysis, aseptic loosening and dislocation. Hopefully cross-linked liner inserts will improve long term outcome in the future.

Introduction: Revision rate after THA in the younger age groups is still unacceptable high and might up to 20% after 10 years. The aim of this investigation is to evaluate risk factors for later revision in patients younger than 50 years at surgery based on the NARA database (Nordic Arthroplasty Register Association).

Materials and Methods: 14,610 primary THA from Denmark, Sweden, and Norway, operated from 1995 to 2007, were included. 49.4% was males, the diagnosis was idiopathic osteoarthrosis (OA) in 46%, childhood disease in 26%, inflammatory arthritis (IA) in 12%, non-traumatic osteonecrosis in 9% and fracture in 6%. 49% of the THA’s were uncemented, 27% cemented, 14% hybrid, and 8% were inverse hybrid THA’s. Cox multiple regression, adjusted for diagnose, age, gender, calendar year and surgical approach, was used to calculate prosthesis survival with any revision as end-point. RR= relative risk (CI= confidence interval).

Results: The overall 10-year survival was 83%. There was no difference between gender (RR=0.94 (0.82–1.07)). IA had a 37% reduced risk of revision compared with OA (RR=0.67 (0.54–0.84)), whereas there was no difference between childhood disease and primary osteoarthrosis. Overall, cemented, uncemented and reverse hybrid THA had a better survival than hybrid THA. Hybrid THA had 24% increased risk compared with cemented (RR=1.24 (1.04–1.49)). There were no difference between cementless and cemented (RR=1.07 (0.92–1.26)). Interestingly, the inverse THA had lower revision rate than cemented THA in men (RR=0.50 (0.25–0.99)). The risk for revision due to aseptic loosening was lowest in cementless THA and reduced to RR=0.55 (0.44–0.69) compared with cemented THA.

Discussion: and Conclusion: Choice of prosthetic concept for younger patients is still of debate. The present study including only patients younger than 50 years of age, showed that overall cemented, uncemented and reverse hybrid THA, had better survival than traditional hybrid. The risk for revision due to aseptic loosening was higher in cemented than cementless THA.

Introduction: In an earlier publication we analysed short-term results of total hip arthroplasty (THA) with Ceramic-on-Ceramic (C-on-C) articulations, and we found that they did not perform better than the Charnley prosthesis with a metal-on-UHMWPE articulation.

Purpose: To examine mid-term results of THA with Con-C articulations, and to compare their results with the most commonly used cemented prosthesis in our register, the Charnley.

Materials and Methods: All THAs with C-on-C articulations were uncemented and they constituted 2506 THAs.

194 of the THAs had articulations with an Alumina liner and a femoral head made of a composite of Alumina and Zirconium oxide ceramic (Biolox delta). This group had a median follow-up of only 1.1 years, and the group was therefore not included in the survival analyses.

2312 of the THAs were uncemented prostheses with Alumina-on-Alumina articulations, with a follow-up of 0–11 years (median 4.3 years). For further analyses we included only patients under the age of 80 years (n = 2209).

We compared the two most common C-on-C cup/stem combinations: Igloo/Filler (n=1402) and Trilogy/SCP (n=363), and a group of others (n= 547). Further we compared the C-on-C prostheses with cemented Charnley prostheses in patients under the age of 80 years, operated during the same time-period. We also compared the C-on-C prostheses with Charnley prostheses in a group limited to patients under the age of 60 years. Prosthesis survival was estimated by Kaplan-Meier and Cox regression analyses adjusted for age and gender.

Results: In patients under the age of 80 years the Charnley prostheses had a statistically significant higher survival than the C-on-C prostheses at 7 years (97.1% and 95.7% respectively, p=0.04). In patients under 60 years of age these analyses gave similar results, although with no statistical significant difference between Charmley and the C-on-C prostheses (p=0.06). There was no statistically significant difference in revision risk among Igloo/Filler, Trilogy/SCP, and a group of all other combinations of cup/stem with a C-on-C articulation. The most common causes for revision of the C-on-C hips were dislocation (n=18) and deep infection (n=16). 3 were revised due to a broken liner and 4 due to a broken head. Of the 194 articulations with Alumina liner and Biolox delta head, one had been revised due to fractured head.

Conclusion: With a follow up of 0–11 years, we did not find superior results of the C-on-C prostheses compared to the Charnley prosthesis. Few revisions were clearly related to failure of the articulations.

Background: The treatment of trochanteric and subtrochanteric fractures is still controversial. In Norway the most commonly used implant for these fractures is the Sliding Hip Screw (SHS), with or without a trochanteric support plate. The Intertan nail (Smith & Nephew) has been launched as a nail with improved biomechanical properties for the treatment of these fractures, but so far it has not been shown that the clinical results are superior to the traditional Sliding Hip Screw.

We wanted to investigate any differences in pain and function between the new Intertan nail and the Sliding Hip Screw in the early postoperative phase.

Materials and Methods: 665 patients older than 60 years with a trochanteric or subtrochanteric fracture were randomized to either a SHS (CHS/DHS) or an Intertan nail in 5 hospitals. For practical reasons only 315 patients (47%) were evaluated at day 5 postoperatively (163 Intertan and 152 SHS), and these patients were used for our analysis. Pain was measured using a Visual Analog Scale (VAS), and early functional mobility by the “Timed Up and Go”- test (TUG-test). T-tests and chi-square tests were used to examine differences between the groups.

Results: The average pain at rest was similar for the 2 groups (VAS 21). Pain at mobilization, however, differed, where patients operated with the Intertan nail had less pain than those operated with the SHS (VAS 47 vs. 53, p = 0.02). The difference between the implants was most pronounced for the simple two-part fractures (AO Type A1). More patients treated with the nail than with the SHS performed the TUG-test at day 5 (85/163 vs. 63/152, p = 0.06), but there was no statistically significant difference regarding the average speed the TUG-test was performed with (71 vs. 66sec, p = 0.36). The implant type did not influence the length of hospital stay.

Discussion/Conclusion: Regarding early postoperative pain and function, there seems to be similar or better results for trochanteric and subtrochanteric fractures treated with the Intertan nail compared to the SHS. The difference in measured pain level was statistically significant, but may not be clinically significant (a difference of VAS 6). We could not detect any significant differences in terms of early functional mobility between the two implants.

In our opinion it still remains to show good long-term results and acceptable complication rates before the new Intertan nail is widely taken into use. Due to the additional costs for the Intertan nail also economic aspects should be considered when choosing the implant and operative method for these fractures.

Introduction: There is an increasing interest in surface replacement arthroplasty (SRA) as an alternative to conventional THA (cTHA) in young and active patients. However, there has been considerable variability in reported outcomes. National joint registry reports have shown increased revision rates compared to cTHA. We analysed outcome measured as non-septic revision rate within two years for SRA in the NARA data base (Nordic Arthroplasty Register Association).

Materials and Methods: 1638 SRA and 163802 cTHA with age up to 73 years and a non-fracture diagnosis, operated from 1995 to 2007, were compared using Cox multiple regression including age, gender, diagnosis, nation and prosthesis type with cTHA divided into cemented, uncemented, hybrid and reversed hybrid fixation. Men below 50 years of age (460 SRA and 7185 cTHA) were analysed as a subset. The SRA cohort with a mean follow-up 1,8 years was also analysed with the same method including age, gender, diagnosis, number of performed SRA per hospital and the four most commonly used prosthesis designs. In an additional analysis femoral head diameter was added, reducing the number of cases to 1552. results are presented as relative risk (RR) with 95 % confidence interval(CI).

Results: SRA had a more than twofold increased revision risk compared to cTHA, RR=2,50 (1,67–3,70), which increased to 3,63 (2,42–5,44) when compared with all cemented THA. In the subpopulation of men below 50 years of age, there was no difference between SRA and any of the cTHA cathegories. Within the SRA group RR was reduced by male gender, RR=0,46 (0,25–0,86), in hospital performing > 70 SRA (RR=0,26, 0,11–0,60) and with use of BHR (Birmingham Hip Resurfacing) compared to all other designs (RR=0,27, 0,12–0,61). The size of the femoral head diameter had no significant influence on the early revision rate.

Discussion and Conclusion: Surface replacement arthroplasty has an increased risk of early revision compared to conventional and cemented THA except for men below 50 years of age. There is a learning curve on the hospital level. Cases with secondary osteoarthritis were comparatively few and were mainly caused by pediatric hip disease. SRA might become an alternative for young men, but our follow up is too short to determine if this indication remains in the longer perspective.

Objective: To study the incidence of joint replacement procedure, arthrodesis, and synovectomy among patients with chronic inflammatory joint disease during the period 1994 to 2004.

Methods: Data from the Norwegian Arthroplasty Register was used to find the number of joint replacement procedures performed in Norway 1994 – 2004. The incidences of arthrodeses and synovectomies were obtained from the Norwegian Patient Register. Incidence rates were calculated based on age, year, and gender specific population rates for the Norwegian population, obtained from Statistics Norway.

Results: There were 8268 primary joint replacements, 3554 arthrodeses, and 5012 synovectomies performed in patients with inflammatory arthritis (IA) during the study period. A reduction in joint replacement procedures and synovectomies took place during the period 1994 to 2004, in patients with IA. For the oldest patients (80 years and older), no such trend was found. During the same time period, the incidence of joint replacements due to osteoarthritis increased. A significant reduction in the incidence of arthrodesis procedures was also found for the total study group, but not for the different subgroups.

Conclusion: The incidence of joint replacements and synovectomies among patients with chronic inflammatory joint disease decreased from 1994 to 2004. This may be the result of improved medical treatment of these patients.

Starting in the 1970s, long-term survivorship of total hip and knee arthroplasty has been under investigation for the Scandinavian population with the aid of implants registries. In the United States, no national arthroplasty registry currently exists. Nationwide inpatient discharge databases in the United States have proven useful when comparing the revision burden in the United States and Scandinavia. For this study, we compared the implant survivorship in the Medicare population with contemporaneous registry-based data from well-established and validated Scandinavian arthroplasty registries. The 5% systematic sample of Medicare claims from 1997 to 2004 were examined for primary and revision THA and TKA claims. The Medicare beneficiary ID was used to follow patients longitudinally between primary and revision surgery. De-identified data from the Norwegian and Swedish national hip and knee registry were also obtained for the same time period. During the 8-year study period, 30,583 and 62,878 elective primary total hip or knee replacements, respectively, were extracted from the Medicare data. In the same time period, 41,823 and 15,927 primary total hips or knees replacements were identified from the Norwegian registry. 82,037 primary total hips were identified from the Swedish registry. Survivorship was assessed by the Kaplan-Meier method, and Cox regression was used to evaluate the effect of patient attributes and cross-country comparisons. The K-M estimate showed that 8 years post-primary surgery, 93.6% of THA and 96.2% of TKA remained revision-free among the elderly Medicare population. By comparison, among Norwegians aged 65 and above, 96.0% of THA and 93.6% of TKA remained revision-free. In the US, men had a significantly higher risk of knee revision than women, but no significant gender difference among hip revision. In Norway, men had a significantly higher risk of hip revision, but no differences in knee revisions. In Sweden, men had a significantly higher risk of hip revision (5.4% vs. 3.3%). Older patients had a reduced risk of revision as compared with younger patients, in both the US and in Norway. The survival of THA is significantly better in Norway than in the US with a hazard ratio of 1.64 (p< 0.05). On the other hand, TKA had a better survival experience in the US than in Norway, with a hazard ratio of 0.55 (p< 0.05). This is the first study to evaluate the utility of Medicare as a source of THA and TKA survivorship data and to compare prosthesis outcomes in Medicare with those from Scandinavian arthroplasty registries. Unlike the Norwegian and Swedish registry data, the reasons for revision (e.g., femoral loosening) are not captured and thus greatly limited the value of the Medicare data as a tool to understand the need for revision, thereby helping to improve implant longevity and to reduce the associated cost and burden to the patient and care provider.

Aims: To calculate one-year survival after dislocated intracapsular femoral neck fractures and to assess factors associated with increased risk of death.

Patients: 2045 patients treated for dislocated intracapsular femoral neck fractures during 2005 were registered in The Norwegian Hip Fracture Registry and were included in the present study.

Methods: Almost all hospitals in Norway reported proximal femoral fractures to the Registry using standard forms filled in by the operating surgeons. Survival was calculated using Kaplan Meier survival analyses, and the impact of factors possibly influencing the survival was estimated using Cox regression analysis. Mortality data for all patients were obtained from Statistics Norway.

Results: 2045 patients having dislocated intracapsular femoral neck fractures operated with 2 pins/screws (1071) and bipolar hemiprosthesis (974) were enrolled in the Registry during 2005. Among these, 333 patients died within the first year after the operation; 2 pins/screws (170) and bipolar hemiprosthesis (163). Factors adversely associated with survival included high age, male gender, dementia and with an increase in preoperative ASA classification. No statistically significant difference was found regarding preoperativ delay or for the two different treatment methods.

Conclusion: After one year there is no difference in risk of death between operation methods; 2 pins/screws and hemiprosthesis, for dislocated femoral neck fractures.

There is an increased early postoperative mortality (operation risk) after joint replacement surgery. This mortality is normally associated with cardiovascular events, such as deep venous thrombosis, pulmonary embolism, and ischemic heart diseases.

Our objective was to quantify the magnitude of the increased mortality and how long the mortality after an operation persists.

We focused on the early postoperative mortality after surgery for total knee and total hip replacements from the national registries in Australia and Norway, which cover more than 95% of all operations in the two nations. Only osteoarthritis patients between 50 and 80 years of age were included. A total of 244.275 patients remained for analyses.

Smoothed intensity curves were calculated for the early postoperative period. Effects of risk factors were studied using a non-parametric proportional hazards model.

The mortality was highest immediately after the operation (~1 deaths per 10.000 patients per day), and it decreased until the 3rd postoperative week. The mortality was virtually the same for both nations and both joints. Mortality increased with age and was higher for males than for females.

A possible reduction of early postoperative mortality is plausible for the immediate postoperative period, and no longer than the 3rd postoperative week.

There has been no general agreement about the use of uncemented hip prostheses in patients with rheumatoid arthritis (RA). In the present study we compared the results for the cemented and uncemented stem that most commonly had been used in RA patients in the Norwegian Arthroplasty Register.

MATERIAL AND Methods: All hospitals in the country participate and report their primary and revision operations of RA patients to the register. This group constitutes 3.5% of the patients in the register. For the present study we included primary prosthesis operations in RA patients during 1987–2005, where either the Corail or the Charnley stem, the most commonly used uncemented and cemented stems, had been used. We calculated survival by the Kaplan-Meier method and by Cox multiple regression with adjustment for age and gender.

Results: The 10 years survival of the total hip prostheses were 81 % in the uncemented group and 89 % in the cemented group. However, the revisions of the uncemented prostheses were mainly performed due to cup problems. With revision of stem for any reason as end-point, the 10-year survival was 98% for the fully HA-coated uncemented Corail stem and 91% for the cemented Charnley stem. In the Cox regression, the risk for revision of the Charnley stem was 3.4 times increased compared to the Corail (95% CI: 1.43–8.06. P< 0.006). Also revision due to aseptic stem loosening was statistically significant increased for the Charnley stem, whereas there was no significant difference concerning revision due to dislocation or periprosthetic fracture.

Conclusions: Both stems had a 10-years survival better than 90%, and the uncemented stem had excellent results in RA patients. However, the uncemented total hip prostheses had inferior results compared to the cemented total hip prostheses due to problems with the uncemented cups that had been used in association with this uncemented stem.

Background: During the 1990s a change in operative technique for primary hip replacement took place in Norway. This study was designed to measure the revision rate in different time periods in cemented Charnley total hip replacements reported to the Norwegian Arthroplasty Register.

Patients and methods: 26 873 primary cemented Charnley total hip replacements reported to the Norwegian Arthroplasty Register in the time periods 1987–91, 92–96, 97–01 and 2002–05 were studied. Only hips with Palacos and Simplex cements with and without antibiotic were studied. To compare the time periods Kaplan Meier analysis was used. To adjust for differences in approach to the hip, age, sex and use of systemic antibiotic prophylaxis Cox regression was used.

Results: There was 28 % less risk of revision due to all causes in the time period 1997–01 compared to 1987–91 (RR=0.72 (95% CI 0.60–0.86), p< 0,001). There was inferior result in the time period 1992–96 compared to 1987–91, but from 1997 there has been an improvement of results due to fewer aseptic loosenings of the femoral component (RR 0.44 (95% CI 0.35–0.56), p< 0.001). There was however more luxations in the later period, and there was no improvement in revisions due to aseptic loosening of the acetabular component.

Conclusion: There has been an improvement in revision rate of the cemented Charnley prosthesis the last two time periods, due to fewer aseptic loosenings of the femoral component. The reason is probably better technique of component placement and better cementation technique. In the future prevention of luxation and better cementation technique of the acetabulum should also be emphasised.

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.

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.