Nordic Arthroplasty Register Association Research Articles

Increasing risk of revision due to infection after primary total hip arthroplasty: results from the Nordic Arthroplasty Register Association.

The incidence of periprosthetic joint infection after total hip arthroplasty (THA) may be increasing. We performed time-trend analyses of risk, rates, and timing of revision due to infection after primary THAs in the Nordic countries from the period 2004-2018. 569,463 primary THAs reported to the Nordic Arthroplasty Register Association from 2004 to 2018 were studied. Absolute risk estimates were calculated by Kaplan-Meier and cumulative incidence function methods, whereas adjusted hazard ratios (aHR) were assessed by Cox regression with the first revision due to infection after primary THA as primary endpoint. In addition, we explored changes in the time span from primary THA to revision due to infection. 5,653 (1.0%) primary THAs were revised due to infection during a median follow-up time of 5.4 (IQR 2.5-8.9) years after surgery. Compared with the period 2004-2008, the aHRs for revision were 1.4 (95% confidence interval [CI] 1.3-1.5) for 2009-2013, and 1.9 (CI 1.7-2.0) for 2014-2018. The absolute 5-year rates of revision due to infection were 0.7% (CI 0.7-0.7), 1.0% (CI 0.9-1.0), and 1.2% (CI 1.2-1.3) for the 3 time periods respectively. We found changes in the time span from primary THA to revision due to infection. Compared with 2004-2008, the aHR for revision within 30 days after THA was 2.5 (CI 2.1-2.9) for 2009-2013, and 3.4 (CI 3.0-3.9) for 2013-2018. The aHR for revision within 31-90 days after THA was 1.5 (CI 1.3-1.9) for 2009-2013, and 2.5 (CI 2.1-3.0) for 2013-2018, compared with 2004-2008. The risk of revision due to infection after primary THA almost doubled, both in absolute cumulative incidence and in relative risk, throughout the period 2004-2018. This increase was mainly due to an increased risk of revision within 90 days of THA. This may reflect a "true" increase (i.e., frailer patients or more use of uncemented implants) and/or an "apparent" increase (i.e., improved diagnostics, changed revision strategy, or completeness of reporting) in incidence of periprosthetic joint infection. It is not possible to disclose such changes in the present study, and this warrants further research.

Does choice of bearings influence the survival of cementless total hip arthroplasty in patients aged 20-55 years? Comparison of 21,594 patients reported to the Nordic Arthroplasty Register Association dataset 2005-2017.

The bearings with the best survivorship for young patients with total hip arthroplasty (THA) should be identified. We compared hazard ratios (HR) of revision of primary stemmed cementless THAs with metal-on-metal (MoM), ceramic-on-ceramic (CoC), and ceramic-on-highly-crosslinked-polyethylene (CoXLP) with that of metal-on-highly-crosslinked-polyethylene (MoXLP) bearings in patients aged 20-55 years with primary osteoarthritis or childhood hip disorders. From the Nordic Arthroplasty Register Association dataset we included 1,813 MoM, 3,615 CoC, 5,947 CoXLP, and 10,219 MoXLP THA in patients operated on between 2005 and 2017 in a prospective cohort study. We used the Kaplan-Meier estimator for THA survivorship and Cox regression to estimate HR of revision adjusted for confounders (including 95% confidence intervals [CI]). MoXLP was used as reference. HRs were calculated during 3 intervals (0-2, 2-7, and 7-13 years) to meet the assumption of proportional hazards. Median follow-up was 5 years for MoXLP, 10 years for MoM, 6 years for CoC, and 4 years for CoXLP. 13-year Kaplan-Meier survival estimates were 95% (CI 94-95) for MoXLP, 82% (CI 80-84) for MoM, 93% (CI 92-95) for CoC, and 93% (CI 92-94) for CoXLP bearings. MoM had higher 2-7 and 7-13 years' adjusted HRs of revision (3.6, CI 2.3-5.7 and 4.1, CI 1.7-10). MoXLP, CoC, and CoXLP had similar HRs in all 3 periods. The 7-13-year adjusted HRs of revision of CoC and CoXLP were statistically non-significantly higher. In young patients, MoXLP for primary cementless THA had higher revision-free survival and lower HR for revision than MoM bearings. Longer follow-up is needed to compare MoXLP, CoC, and CoXLP.

Impact of Nordic Arthroplasty Register Association (NARA) collaboration on demographics, methods and revision rates in knee arthroplasty: a register-based study from NARA 2000-2017.

We have previously observed differences in treatment and outcome of knee arthroplasties in the Nordic countries. To evaluate the impact of Nordic collaboration in the last 15 years we aimed to compare patient demographics, methods, and revision rates in primary knee arthroplasties among the 4 Nordic countries. We included 535,051 primary knee arthroplasties reported 2000-2017 from the Nordic Arthroplasty Register Association (NARA) database. Kaplan-Meier analysis (KM) and restricted mean survival time (RMST) analysis were used to evaluate the cumulative revision rate (CRR) and RMST estimates with 95% confidence intervals (CI) and to compare countries in relation to risk of revision for any reason. After 2010, the increase in incidence of knee arthroplasty plateaued in Sweden and Denmark but continued to increase in Finland and Norway. In 2017 the incidence was highest in Finland with 226 per 105 person-years, while it was less than 150 per 105 in the 3 other Nordic countries. In total knee arthroplasties performed for osteoarthritis (OA), overall CRR at 15 years for revision due to any reason was higher in Denmark (CRR 9.6%, 95% CI 9.2-10), Norway (CRR 9.1%, CI 8.7-9.5), and Finland (CRR 7.0%, CI 6.8-7.3) compared with Sweden (CRR 6.6%, CI 6.4-6.8). There were differences among the countries in use of implant brand and type, fixation, patellar component, and use of unicompartmental knee arthroplasty. We evinced a slowing growth of incidence of knee arthroplasties in the Nordic countries after 2010 with Finland having the highest incidence. We also noted substantial differences among the 4 Nordic countries, with Sweden having a lower risk of revision than the other countries. No impact of NARA could be demonstrated and CRR did not improve over time.

Editorial: Different, yet strong together: the Nordic Arthroplasty Register Association (NARA)

The Nordic Arthroplasty Register Association (NARA) was established in 2007 by hip and knee arthroplasty registry leaders from Denmark, Norway, and Sweden. Purportedly, the idea of combining nation...

Total hip arthroplasties in the Dutch Arthroplasty Register (LROI) and the Nordic Arthroplasty Register Association (NARA): comparison of patient and procedure characteristics in 475,685 cases

Background and purpose — Collaborations between arthroplasty registries are important in order to create the possibility of detecting inferior implants early and improve our understanding of differences between nations in terms of indications and outcomes. In this registry study we compared patient and procedure characteristics, and revision rates in the Nordic Arthroplasty Register Association (NARA) database and the Dutch Arthroplasty Register (LROI). Patients and methods — All total hip arthroplasties (THAs) performed in 2010–2016 were included from the LROI (n = 184,862) and the NARA database (n = 290,823), which contains data from Denmark, Norway, Sweden, and Finland. Descriptive statistics and Kaplan–Meier survival analyses based on all reasons for revision and stratified by fixation were performed and compared between countries. Results — In the Netherlands, the proportion of patients aged < 55 years (9%) and male patients (34%) was lower than in Nordic countries (< 55 years 11–13%; males 35–43%); the proportion of osteoarthritis (OA) (87%) was higher compared with Sweden (81%), Norway (77%), and Denmark (81%) but comparable to Finland (86%). Uncemented fixation was used in 62% of patients in the Netherlands, in 70% of patients in Denmark and Finland, and in 28% and 19% in Norway and Sweden, respectively. The 5-year revision rate for THAs for OA was lower in Sweden (2.3%, 95% CI 2.1–2.5) than in the Netherlands (3.0%, CI 2.9–3.1), Norway (3.8%, CI 3.6–4.0), Denmark (4.6%, CI 4.4–4.8), and Finland (4.4%, CI 4.3–4.5). Revision rates in Denmark, Norway, and Finland were higher for all fixation groups. Interpretation — Patient and THA procedure characteristics as well as revision rates evinced some differences between the Netherlands and the Nordic countries. The Netherlands compared best with Denmark in terms of patient and procedure characteristics, but resembled Sweden more in terms of short-term revision risk. Combining data from registries like LROI and the NARA collaboration is feasible and might possibly enable tracking of potential outlier implants.

Similar early mortality risk after cemented compared with cementless total hip arthroplasty for primary osteoarthritis: data from 188,606 surgeries in the Nordic Arthroplasty Register Association database

Background and purpose — Current literature indicates no difference in 90-day mortality after cemented compared with cementless total hip arthroplasty (THA). However, previous studies are hampered by potential selection bias and suboptimal adjustment for comorbidity confounding. Therefore, we examined the comorbidity-adjusted mortality up to 90 days after cemented compared with cementless THA performed due to osteoarthritis. Patients and methods — Using the Nordic Arthroplasty Register Association database, 2005–2013, we included 108,572 cemented and 80,034 cementless THA due to osteoarthritis. We calculated the Charlson comorbidity index of each patient based on data from national patient registers. The Kaplan–Meier method was used to estimate unadjusted all-cause mortality. Cox regression was used to estimate hazard ratios (HR) with 95% confidence intervals (CI) for 14, 30-, and 90-day mortality comparing cemented with cementless THA, adjusting for age, sex, comorbidity, nation, and year of surgery. Results — Cumulative all-cause mortality within 90 days was 0.41% (CI 0.37–0.46) after cemented and 0.26% (CI 0.22–0.30) after cementless THA. The adjusted HR for cemented vs. cementless fixation was 0.97 (CI 0.79–1.2), and similar risk estimates were obtained for mortality within 14 (adjusted HR 0.91 [CI 0.64–1.3]) and 30 days (adjusted HR 0.94 [CI 0.71–1.3]). We found no clinically relevant differences in mortality between cemented and cementless THA in analyses stratified by age, sex, Charlson comorbidity index, or year of surgery. Interpretation — After adjustment for comorbidity as an important confounder, we observed similar early mortality between the 2 fixation techniques.

Association between fixation type and revision risk in total knee arthroplasty patients aged 65 years and older: a cohort study of 265,877 patients from the Nordic Arthroplasty Register Association 2000–2016

Background and purpose — The population of the Nordic countries is aging and the number of elderly patients undergoing total knee arthroplasty (TKA) is also expected to increase. Reliable fixation methods are essential to avoid revisions. We compared the survival of different TKA fixation concepts with cemented fixation as the gold standard. Patients and methods — We used data from the Nordic Arthroplasty Register Association (NARA) database of 265,877 unconstrained TKAs performed for patients aged ≥ 65 years with primary knee osteoarthritis between 2000 and 2016. Kaplan–Meier (KM) survival analysis with 95% confidence intervals (CI) and the Cox multiple-regression model were used to compare the revision risk of the fixation methods. Results — Cemented fixation was used in 243,166 cases, uncemented in 8,000, hybrid (uncemented femur with cemented tibia) in 14,248, and inverse hybrid (cemented femur with uncemented tibia) fixation in 463 cases. The 10-year KM survivorship (95% CI) of cemented TKAs was 96% (96 − 97), uncemented 94% (94 − 95), hybrid 96% (96 − 96), and inverse hybrid 96% (94 − 99), respectively. Uncemented TKA was associated with increased risk of revision compared with the cemented TKA; the adjusted hazard ratio was 1.3 (95% CI 1.1 − 1.4). Interpretation — Cemented, hybrid, and inverse hybrid TKAs showed 10-year survival rates exceeding 95%. Uncemented fixation was associated with an increased risk of revision in comparison with cemented fixation. As both hybrid and inverse hybrid fixation were used in only a limited number of TKAs, indicating possibility of selection bias in their favor, cemented TKA still remains the gold standard, as it works reliably in the hands of many.

Low arthroplasty survival after treatment for proximal humerus fracture sequelae: 3,245 shoulder replacements from the Nordic Arthroplasty Register Association

Background and purpose — Proximal humerus fractures (PHF) may result in sequelae indicating arthroplasty. We report cumulative survival rates and reasons for revision after arthroplasty for proximal humerus fracture sequelae (PHFS).Patients and methods — Data were derived from the Nordic Arthroplasty Register Association. The Kaplan–Meier method was used to illustrate survival rates. A scaled Schoenfeld residual plot was used to report the risk of revision for men relative to women in patients who were treated with reverse shoulder arthroplasty (RSA). Revision was defined as removal or exchange of any component or the addition of a glenoid component.Results — 30,190 primary arthroplasties were reported from 2004 to 2016, of which 3,245 were for PHFS. The estimated 1-, 5-, and 10-year cumulative survival rates (95% CI) were 96% (95–97), 90% (89–92), and 86% (83–88) for stemmed hemiarthroplasty and 94% (92–95), 89% (87–91), and 86% (82–90) for RSA with a median time to revision of 18 months (IQR 9–44) and 3 months (IQR 0–17). The risk of revision for men relative to women in patients who were treated with RSA was 3.2 (1.9–5.1) 0–1 year after surgery and 1.9 (0.9–4.1) 1–8 years after surgery. The estimated 1-, 5-, and 10-year cumulative survival rates (95% CI) were 94% (92–96), 88% (85–90), and 80% (75–86) for men and 95% (94–96), 86% (84–89), and 81% (77–84) for young patients.Interpretation — Shoulder arthroplasty for PHFS was associated with lower survival rates, compared with previously published results of shoulder arthroplasty for acute PHF. The low arthroplasty survival rates for men and young patients especially are worrying.

Is there a reduction in risk of revision when 36-mm heads instead of 32 mm are used in total hip arthroplasty for patients with proximal femur fractures?

Background and purpose — 32-mm heads are widely used in total hip arthroplasty (THA) in Scandinavia, while the proportion of 36-mm heads is increasing as they are expected to increase THA stability. We investigated whether the use of 36-mm heads in THA after proximal femur fracture (PFF) is associated with a lower risk of revision compared with 32-mm heads.Patients and methods — We included 5,030 patients operated with THA due to PFF with 32- or 36-mm heads from the Nordic Arthroplasty Register Association database. Each patient with a 36-mm head was matched with a patient with a 32-mm head, using propensity score. The patients were operated between 2006 and 2016, with a metal or ceramic head on a polyethylene bearing. Cox proportional hazards models were fitted to estimate the unadjusted and adjusted hazard ratio (HR) with 95% confidence intervals (CI) for revision for any reason and revision due to dislocation for 36-mm heads compared with 32-mm heads.Results — 36-mm heads had an HR of 0.9 (CI 0.7–1.2) for revision for any reason and 0.8 (CI 0.5–1.3) for revision due to dislocation compared with 32-mm heads at a median follow-up of 2.5 years (interquartile range 1–4.4).Interpretation — We were not able to demonstrate any clinically relevant reduction of the risk of THA revision for any reason or due to dislocation when 36-mm heads were used versus 32-mm. Residual confounding due to lack of data on patient comorbidities and body mass index could bias our results.

Low risk of revision after reverse shoulder arthroplasty for acute proximal humeral fractures

BackgroundReverse shoulder arthroplasty (RSA) has gained popularity in the treatment of proximal humeral fractures (PHFs), especially in elderly patients. The purpose of this study was to investigate the use of RSA implants for acute PHFs and risk of revision, as well as risk factors for revision.MethodsRSA implants for acute PHFs were identified from the Nordic Arthroplasty Register Association registry data from 2004 to 2016. Kaplan-Meier survival analysis was used to calculate implant survival. Cox multiple regression analysis was used to calculate the adjusted revision rate for sex, age, country of operation, and year of surgery.ResultsThe study included 1523 RSA implants for PHFs (84% women; average age, 77 years; average follow-up time, 2.5 years). The 5-year cumulative implant survival rate was 97% (confidence limits, 95.5% and 98%). Revision was performed for 33 implants (2%). The most common reason for revision was instability, occurring in 11 cases (0.7%), followed by fracture, occurring in 6 (0.4%), and infection, occurring in 5 (0.3%). Four different arthroplasty brands were used in this cohort, with the Delta Xtend in two-thirds of cases (n = 1025). Age younger than 60 years and male sex were associated with slightly higher rates of revision; however, these differences did not reach statistical significance (hazard ratio of 2.02 with P = .075 and hazard ratio of 3.23 with P = .057, respectively).ConclusionThe use of RSA for acute PHFs is increasing in the Nordic countries. The short-term risk of revision is low. The main reason for revision of RSA for this indication is instability.

The effect of fixation type on the survivorship of contemporary total knee arthroplasty in patients younger than 65 years of age: a register-based study of 115,177 knees in the Nordic Arthroplasty Register Association (NARA) 2000–2016

Background and purpose — Cemented fixation is regarded as the gold standard in total knee arthroplasty (TKA). Among working-age patients, there has been controversy regarding the optimal fixation method in TKA. To address this issue, we conducted a register-based study to assess the survivorship of cemented, uncemented, hybrid, and inverse hybrid TKAs in patients aged < 65 years.Patients and methods — We used the Nordic Arthroplasty Register Association data of 115,177 unconstrained TKAs performed for patients aged < 65 years with primary knee osteoarthritis over 2000–2016. Kaplan–Meier (KM) survival analysis with 95% confidence intervals (CI) and Cox multiple-regression model with adjustment for age, sex, and nation were used to compare fixation methods in relation to revision for any reason.Results — The 10-year KM survivorship of cemented TKAs was 93.6% (95% CI 93.4–93.8), uncemented 91.2% (CI 90.1–92.2), hybrid 93.0% (Cl 92.2–93.8), and inverse hybrid 96.0% (CI 94.1–98.1). In the Cox model, hybrid TKA showed decreased risk of revision after 6 years’ follow-up compared with the reference group (cemented) (hazard ratio [HR] 0.5 [CI 0.4–0.8]), while uncemented TKAs showed increased risk of revision both < 1 year (HR 1.4 [1.1–1.7]) and > 6 years’ (HR 1.3 [1.0–1.7]) follow-up compared to the reference.Interpretation — Both cemented and hybrid TKAs had 10-year survival rates exceeding 92–>93% in patients aged < 65 years. Cemented TKA, however, was used in the vast majority (89%) of the operations in the current study. As it performs reliably in the hands of many, it still deserves the status of gold standard for TKA in working-age patients.

Low Survival Rates of Stemmed Hemiarthroplasty and Reverse Arthroplasty After Treatment for Proximal Humerus Fracture Sequelae. A Register-Based Study from the Nordic Arthroplasty Register Association

Low Survival Rates of Stemmed Hemiarthroplasty and Reverse Arthroplasty After Treatment for Proximal Humerus Fracture Sequelae. A Register-Based Study from the Nordic Arthroplasty Register Association

The Short-Term Survival of Total Stemless Shoulder Arthroplasty for Osteoarthritis is Comparable to that of Total Stemmed Shoulder Arthroplasty: A Nordic Arthroplasty Register Association Study

The Short-Term Survival of Total Stemless Shoulder Arthroplasty for Osteoarthritis is Comparable to that of Total Stemmed Shoulder Arthroplasty: A Nordic Arthroplasty Register Association Study

Reduced Revision Risk for Dual-Mobility Cup in Total Hip Replacement Due to Hip Fracture: A Matched-Pair Analysis of 9,040 Cases from the Nordic Arthroplasty Register Association (NARA).

The dual-mobility acetabular cup (DMC) has an additional bearing consisting of a mobile polyethylene component between the prosthetic head and the outer metal shell. This design has gained popularity in revision total hip arthroplasty (THA) and in primary treatment of femoral neck fractures with the anticipation of a reduced risk of THA instability. Our primary aim was to evaluate the overall revision risk of these cups on the basis of data from the Nordic Arthroplasty Register Association (NARA) database, and our secondary aim was to study specific revision causes including dislocation. Propensity score matching for age, sex, fixation of the cup and stem, and the year of surgery (2001 to 2014) was used to match 4,520 hip fractures treated with a DMC to 4,520 hip fractures treated with conventional THA (control group). Competing risk regression analyses with revision or death as the end point were used. Revision was defined as a secondary surgical procedure in which any component of the implant was removed or exchanged. In addition, revision of the cup was analyzed. The DMCs had a lower risk of revision compared with conventional THA, with an adjusted hazard ratio (AHR) of 0.75 (95% confidence interval [CI] = 0.62 to 0.92). This was consistent after adjusting for surgical approach. DMCs had a lower risk of revision due to dislocation (AHR = 0.45 [95% CI = 0.30 to 0.68]) but we found no difference regarding revision for deep infection. Revision of the acetabular component, both in general and due to dislocation, was more frequent with the use of conventional cups. The risk of death was higher in the DMC group (AHR = 1.49 [95% CI = 1.40 to 1.59]). The use of a DMC as primary treatment for hip fracture was associated with a lower risk of revision in general and due to dislocation in particular. The total number of DMCs analyzed (4,520) likely exceeds any cohort of DMC-treated fractures published to date. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Homogeneity in prediction of survival probabilities for subcategories of hipprosthesis data: the Nordic Arthroplasty Register Association, 2000-2013.

Introduction: The four countries in the Nordic Arthroplasty Register Association (NARA) share geographic proximity, culture, and ethnicity. Pooling data from different sources in order to obtain higher precision and accuracy of survival-probability estimates is appealing. Nevertheless, survival probabilities of hip replacements vary between the countries. As such, risk prediction for individual patients within countries may be problematic if data are merged. In this study, our primary question was to address when data merging for estimating prosthesis survival in subcategories of patients is advantageous for survival prediction of individual patients, and at what sample sizes this may be advised.Methods: Patients undergoing total hip replacements for osteoarthritis between January 1, 2000 and December 31, 2013 in the four Nordic countries were studied. A total of 184,507 patients were stratified into 360 patient subcategories based on country, age-group, sex, fixation, head size, and articulation. For each patient category, we determined the sample size needed from a single country to obtain a more accurate and precise estimate of prosthesis-survival probability at 5 and 10 years compared to an estimate using data from all countries. The comparison was done using mean-square error.Results: We found large variations in the sample size needed, ranging from 40 to 2,060 hips, before an estimate from a single Nordic country was more accurate and precise than estimates based on the NARA data.Conclusion: Using pooled survival-probability estimates for individual risk prediction may be imprecise if there is heterogeneity in the pooled data sources. By applying mean-square error, we demonstrate that for small sample sizes, applying the larger NARA database may provide a more accurate and precise estimate; however, this effect is not consistent and varies with the characteristics of the subcategory.

The benefits of collaboration: the Nordic Arthroplasty Register Association.

The Nordic Arthroplasty Register Association (NARA) was established in 2007 by arthroplasty register representatives from Sweden, Norway and Denmark with the overall aim to improve the quality of research and thereby enhance the possibility for quality improvement with arthroplasty surgery. Finland joined the NARA collaboration in 2010.NARA minimal hip, knee and shoulder datasets were created with variables that all countries can deliver. They are dynamic datasets, currently with 25 variables for hip arthroplasty, 20 for knee arthroplasty and 20 for shoulder arthroplasty.NARA has published statistical guidelines for the analysis of arthroplasty register data. The association is continuously working on the improvement of statistical methods and the application of new ones.There are 31 published peer-reviewed papers based on the NARA databases and 20 ongoing projects in different phases. Several NARA publications have significantly affected clinical practice. For example, metal-on-metal total hip arthroplasty and resurfacing arthroplasty have been abandoned due to increased revision risk based on i.a. NARA reports. Further, the use of uncemented total hip arthroplasty in elderly patients has decreased significantly, especially in Finland, based on the NARA data.The NARA collaboration has been successful because the countries were able to agree on a common dataset and variable definitions. The collaboration was also successful because the group was able to initiate a number of research projects and provide answers to clinically relevant questions. A number of specific goals, set up in 2007, have been achieved and new one has emerged in the process.Cite this article: EFORT Open Rev 2019;4 DOI: 10.1302/2058-5241.4.180058

Reverse shoulder arthroplasty has a higher risk of revision due to infection than anatomical shoulder arthroplasty: 17 730 primary shoulder arthroplasties from the Nordic Arthroplasty Register Association.

The aim of this study was to use national registry database information to estimate cumulative rates and relative risk of revision due to infection after reverse shoulder arthroplasty. We included 17 730 primary shoulder arthroplasties recorded between 2004 and 2013 in The Nordic Arthroplasty Register Association (NARA) data set. With the Kaplan-Meier method, we illustrated the ten-year cumulative rates of revision due to infection and with the Cox regression model, we reported the hazard ratios as a measure of the relative risk of revision due to infection. In all, 188 revisions were reported due to infection during a mean follow-up of three years and nine months. The ten-year cumulative rate of revision due to infection was 1.4% overall, but 3.1% for reverse shoulder arthroplasties and 8.0% for reverse shoulder arthroplasties in men. Reverse shoulder arthroplasties were associated with an increased risk of revision due to infection also when adjusted for sex, age, primary diagnosis, and year of surgery (relative risk 2.41 (95% confidence interval 1.26 to 5.59); p = 0.001). The overall incidence of revision due to infection was low. The increased risk in reverse shoulder arthroplasty must be borne in mind, especially when offering it to men. Cite this article: Bone Joint J 2019;101-B:702-707.

Outcome of 881 total hip arthroplasties in 747 patients 21 years or younger: data from the Nordic Arthroplasty Register Association (NARA) 1995–2016

Background and purpose — The literature is scarce on the outcome of the youngest patients with total hip arthroplasties (THAs). We analyzed register data, revision risk, and related factors in patients 21 years or younger with THAs in the Nordic Arthroplasty Register Association (NARA).Patients and methods — We included all THA patients 21 years or younger reported during 1995 through 2016 to the Danish, Finnish, Norwegian, and Swedish hip arthroplasty registers and merged these into the NARA dataset. Primary outcome was any implant revision.Results — We identified 881 THAs in 747 patients. Mean age at primary surgery was 18 years (9–21). The indications for THA were pediatric hip diseases (33%), systemic inflammatory disease (23%), osteoarthritis (4%), avascular necrosis (12%), hip fracture sequelae (7%), and other diagnoses (21%). Unadjusted 10-year survival for all THAs was 86%. Comparison between indications showed no differences in survival. Uncemented implants were used most frequently. Survival for uncemented and cemented implants was the same adjusted for sex, indication, head size, and time period for primary surgery. Aseptic loosening was the main cause of revision.Interpretation — Both cemented and uncemented fixations seem to be a viable option in this age group, but with a lower implant survival than in older patient groups.

Optimal duration of anticoagulant thromboprophylaxis in total hip arthroplasty: new evidence in 55,540 patients with osteoarthritis from the Nordic Arthroplasty Register Association (NARA) group

Background and purpose — The recommended optimal duration of the thromboprophylaxis treatment in total hip arthroplasty (THA) patients has been a matter of debate for years. We examined the association between short (1–5 days), standard (6–14 days), and extended (≥ 15 days) duration of thromboprophylaxis, with regards to the risk of venous thromboembolism (VTE), major bleeding, and death in unselected THA patients.Patients and methods — We performed a cohort study using prospectively collected data from the population-based hip arthroplasty registries, prescription databases, and patient administrative registries in Denmark and Norway. We included 55,540 primary THA patients with osteoarthritisResults — The 90-day cumulative incidence of VTE was 1.0% for patients with standard treatment (reference), 1.1% for those with short-term treatment (adjusted hazard ratio [aHR] of 1.1, 95% confidence interval (CI) 0.8–1.5) and 1.0% for those with extended treatment (aHR of 0.9, CI 0.8–1.2). The aHRs for major bleeding were 1.1 (CI 0.8–1.6) for short and 0.8 (CI 0.6–1.1) for extended vs. standard treatment. In addition, patients with short and extended treatment had aHRs for death of 1.2 (CI 0.8–1.8) and 0.8 (CI 0.5–1.1) vs. standard treatment, respectively. Patients who started short treatment postoperatively had an aHR for death of 1.8 (CI 1.1–3.1) and absolute risk difference of 0.2%, whereas patients who started short treatment preoperatively had an aHR for death of 0.5 (CI 0.2–1.2) and absolute risk difference of 0.3% compared with patients who had standard treatment with post- and preoperative start, respectively.Interpretation — In routine clinical practice, we observed no overall clinically relevant difference in the risks of VTE and major bleeding within 90 days of THA with respect to thromboprophylaxis duration. However, our data indicate that short-term thromboprophylaxis started postoperatively is associated with increased 90-day mortality. The significance of these data should be explored further.

The short-term survival of total stemless shoulder arthroplasty for osteoarthritis is comparable to that of total stemmed shoulder arthroplasty: a Nordic Arthroplasty Register Association study

The purpose of this study was to compare the short-term survival rate of total stemless, metaphyseal fixated, shoulder arthroplasty with that of total stemmed shoulder arthroplasty in the treatment of osteoarthritis. Data were collected by the national arthroplasty registries in Denmark, Finland, Norway, and Sweden and merged into 1 dataset under the umbrella of the Nordic Arthroplasty Register Association. For the present study, we included all patients with osteoarthritis treated with either stemless (n = 761) or stemmed (n = 4398) shoulder arthroplasty from 2011 to2016. A total of 21 (2.8%) stemless and 116 (2.6%) stemmed shoulder arthroplasties were revised. The 6-year unadjusted cumulative survival rates were 0.953 for stemless shoulder arthroplasty and 0.958 for stemmed shoulder arthroplasty, P = .77. The most common indication for revision of both arthroplasty types was infection. Five (0.7%) stemless and 16 (0.4%) stemmed shoulder arthroplasties were revised because of loosening of either the glenoid or the humeral component. In the multivariate cox regression model, which included age, category, gender, year of surgery, previous surgery, and arthroplasty type, the hazard ratio (HR) for revision of the stemless shoulder arthroplasty was 1.00 (95% confidence interval [CI], 0.63-1.61), P = .99, with the stemmed shoulder arthroplasty as reference. Male gender (HR = 1.50 [95% CI, 1.06-2.13], P = .02) and previous surgery (HR = 2.70 [95% CI, 1.82-4.01], P < .001) were associated with increased risk of revision. The short-term survival of total stemless shoulder arthroplasty appears comparable with total stemmed shoulder arthroplasty, but longer observation time is needed to confirm whether they continue to perform equally.