Guideline for RSA and CT-RSA implant migration measurements: an update of standardizations and recommendations.

Opening remarks: These guidelines are the result of discussions within a diverse group of RSA researchers. They were approved in December 2023 by the board and selected members of the International Radiostereometry Society to update the guidelines by Valstar et al. [1]. By adhering to these guidelines, RSA studies will become more transparent and consistent in execution, presentation, reporting, and interpretation. Both authors and reviewers of scientific papers using RSA may use these guidelines, summarized in the Checklist, as a reference. Deviations from these guidelines should have the underlying rationale stated.

What is the Role of Stem Size and Offset in the Risk of Nonseptic Revision of the Exeter® 150-mm Stem? A Study From the Swedish Arthroplasty Register.

BACKGROUND: The Exeter® stem is used worldwide, often in older patients, and it is the second most commonly used cemented stem design in Sweden. Previous studies have shown that for cemented stems with a composite beam, the smallest sizes result in an increased risk of revision for mechanical failure. However, little is known about whether the survivorship of the polished Exeter stem, which generally has been shown to be good, might be associated with design parameters such as stem dimensions or offset at extreme implant sizes. QUESTION/PURPOSE: Are differences in (1) stem size or (2) offset of the standard Exeter V40 150-mm stem associated with differences in the risk of stem revision for aseptic loosening? METHODS: Between 2001 and 2020, 47,161 Exeter stems were reported to the Swedish Arthroplasty Register, with very high coverage and completeness documented during the period studied. In this cohort, we included patients with primary osteoarthritis who underwent surgery with a standard Exeter stem length of 150 mm and V40 cone with any type of cemented cups that had had at least 1000 reported insertions. This selection resulted in a study cohort representing 79% (37,619 of 47,161) of the total number of Exeter stems in the registry during that time. The primary study outcome was stem revision for aseptic indications such as loosening, periprosthetic fracture, dislocation, and implant fracture. A Cox regression was performed, with adjustment for age, gender, surgical approach, year of surgery, use of highly crosslinked polyethylene cups, and femoral head size and length dictated by the shape of the head trunnion. Adjusted hazard ratios are presented with 95% confidence intervals. Two separate analyses were performed. The first analysis excluded stems with the highest offsets (50 mm and 56 mm, which were not available for stem size 0). The second analysis excluded stem size 0 to include all offsets. Because stem survival was not proportional over time, we divided the analyses into two insertion periods, 0 to 8 years and beyond 8 years. RESULTS: Stem size 0 (compared to size 1) was associated with an increased risk of revision up to 8 years when all stem sizes were included (first analysis 0 to 8 years, HR 1.7 [95% CI 1.2 to 2.3]; p = 0.002). Forty-four percent (63 of 144) of revisions of size 0 stems were for periprosthetic fracture. There was no consistent association between stem size and risk of aseptic stem revision when size 0 was excluded in the second analysis beyond 8 years. The most common offset (44 mm) was associated with an increased risk of revision (compared with 37.5 mm) up to 8 years when all sizes were included (first analysis, HR 1.6 [95% CI 1.1 to 2.1]; p = 0.01). In the second analysis (beyond 8 years, all offsets included), offset of 44 mm was compared with offset of 37.5 mm; compared with the first period, this offset was associated with a reduced risk (HR 0.6 [95% CI 0.4 to 0.9]; p = 0.005). CONCLUSION: We found overall high survival of the Exeter stem, with generally little or no influence of stem variations on the risk of aseptic revision. However, stem size 0 was associated with an increased risk of revision mainly for periprosthetic fractures. If the femoral anatomy offers a choice between sizes 0 and 1 in patients with poor bone quality who are at risk of periprosthetic fracture, our data speak in favor of choosing the larger stem if the surgeon believes it is safe to insert the larger size, or, if available, another stem design that has a documented lower risk of this complication. For patients with good cortical bone quality but very narrow canals, a cementless stem may also be a good alternative. LEVEL OF EVIDENCE: Level III, therapeutic study.

Outcome of patients with osteoarthritis aged 90 to 101 years after cemented total hip arthroplasty: 1,385 patients from the Swedish Arthroplasty Register.

BACKGROUND AND PURPOSE: Few studies have focused on nonagenarians treated with total hip arthroplasty (THA). We investigated 30- and 90-day postoperative mortality, patient-reported outcome measures (PROMs), reoperation rate, risk factors for reoperation, and relative patient survival in nonagenarians or older. PATIENTS AND METHODS: 167,091 patients with primary cemented THA performed for osteoarthritis between 1992 and 2019 were identified in the Swedish Arthroplasty Register. Patients were divided into age groups based on age at time of surgery: 60-74 (n = 90,285), 75-89 (n = 75,421), and > 90 years (n = 1,385). Mortality rate, PROMs (pain-Likert scale, satisfaction-Likert scale, EQ-VAS, n = 67,553), reoperation rate, risk factors for reoperation, and relative patient survival were studied. RESULTS: The nonagenarians had the highest postoperative mortality rate, 1.7% and 2.6% at 30 and 90 days, respectively. Nonagenarian females reported significantly lower pre- and postoperative EQ-VAS compared with patients aged 60-89 years but reported least pain and highest patient satisfaction 1 year after surgery. At 2 years the nonagenarians had highest reoperation frequency-2.7%-due to infection (1.5%), dislocation (0.8%), and periprosthetic fracture (0.4%). Increasing age, male sex, and polished stem were associated with higher risk of reoperation within 2 years. 8-year age- and sex-matched relative survival was highest among nonagenarians (study group/matched population: ≥ 90 years 3.4, 95% confidence interval [CI] 3.0-3.8; 75-89 years: 1.4, CI 1.4-1.4, and 60-74 years: 1.1, CI 1.1-1.1). CONCLUSION: 30- and 90-day postoperative mortality and reoperation rates were higher in nonagenarians but PROM data showed least pain and highest patient satisfaction 1 year after surgery with THA among female nonagenarians with primary osteoarthritis.

Fracture pattern and risk factors for reoperation after treatment of 156 periprosthetic fractures around an anatomic cemented hip stem.

BACKGROUND AND PURPOSE: The Lubinus SP2 stem has been associated with a very low risk of periprosthetic femoral fractures (PPFFs). We aimed, primarily, to study the radiographic morphology of PPFFs close to a Lubinus SP2 stem. Secondarily, we analyzed whether higher reoperation rate was correlated to the revision method chosen or to the characteristics of the fracture and of the bone. PATIENTS AND METHODS: The study included 156 femoral fractures close to a Lubinus cemented stem. These fractures were treated in 40 hospitals in Sweden between 2006 and 2011 and were followed up until 2019. Data from the Swedish Arthroplasty Register was used. Medical records and radiographs were studied. The fractures were classified according to the Vancouver classification. The fracture location and anatomy were delineated. We also measured the remaining attachment index (RAI) and the canal thickness ratio. RESULTS: Vancouver type C (n = 101) and spiral fractures (n = 67, 41 in Vancouver C and 26 in Vancouver B) were the most common fracture types. 4 fractures were avulsion of the greater trochanter. The remaining 51 fractures occurred around the stem (B1: 25, B2: 16, and B3: 10). B fractures were more commonly reoperated on (18 of 51, 35%) than type C fractures (11 of 101, 11%, P = 0.001). In most femurs with type B3 fracture, the fracture line covered an area only around the stem, but in all B1 and in 11 of 16 B2 fractures, it was extended even distal to the stem. ORIF instead of stem revision in B2 fractures, use of short stems or plates, and inadequate reduction of the fractures were risk factors for subsequent reoperations. CONCLUSION: The higher reoperation rate in type B fractures, compared with fractures distal to the stem, could be caused by their higher degree of complexity and reduced capacity for healing in the region around the stem.

Corrigendum: Similar outcome with a new anteverted or a straight standard stem: a randomized study of 72 total hip arthroplasties evaluated with clinical variables, radio-stereometry, and DXA up to 2 years.

When we checked our data in our article "Similar outcome with a new anteverted or a straight standard stem: a randomized study of 72 total hip arthroplasties evaluated with clinical variables, radiostereometry, and DXA up to 2 years" by Karin Rilby, Maziar Mohaddes, Emma Nauclér, and Johan Kärrholm, Acta Orthop 2021; 92, Published online October 21, 2021 we noticed that the numbers in Table 7 (Supplementary data) were incorrect. We have not been able to fully reconstruct the reason for this error. We are sorry for this mistake. Even if the corrected numbers are different the overall conclusions will be same and also the statistical significances.

No difference in clinical outcome but in RSA in total knee arthroplasty with the ATTUNE vs. the PFC Sigma: a randomized trial with 2-year follow-up.

BACKGROUND AND PURPOSE: Despite usage of the ATTUNE total knee arthroplasty (TKA) for about 10 years, few randomized trials exist. We evaluated whether the ATTUNE CR design showed improved clinical results compared with the PFC Sigma CR after 2 years and if there was a difference in tibial component migration. PATIENTS AND METHODS: 96 patients with knee osteoarthritis were randomly treated with cemented ATTUNE or PFC Sigma TKA. 42 patients with the ATTUNE and 48 with the PFC Sigma attended the 2-year follow-up. Patient-reported outcome measurements (PROMs), migration measured with RSA, implant position, and the development of radiolucent zones were studied. Non-parametric tests and repeated measures analysis were used at the statistical evaluation. RESULTS: The Oxford Knee Score (OKS) at 2 years (primary outcome) and neither of the secondary PROM outcomes differed between the groups (mean difference OKS ATTUNE - PFC: -0.08, 95% confidence interval [CI] -2.9 to 2.7). RSA showed posterior tilt of the tibial component in the ATTUNE group with proximal lift-off anteriorly and subsidence of the tibial tray posteriorly. In contrast, the PFC Sigma tibial component tilted forward (mean difference ATTUNE - PFC: -0.7°, CI -1.1° to -0.4°) with maximum subsidence in the front and maximum lift-off of the posterior edge. The postoperative implant positions and the extension of radiolucent lines around the tibial component at 2 years did not differ. CONCLUSION: We found no significant differences in clinical outcome between the 2 groups but minor differences in migration pattern of the tibial component. The clinical long-term significance of this finding if any is not known.

Computed tomography-based radiostereometric analysis in orthopedic research: practical guidelines.

Early implant migration is an indicator of the long-term survival/failure of implants. CT-based radio-stereometric analysis (CT-RSA) is a precise method for measuring and visualizing implant migration in vivo using image processing of CT scans. This makes the method widely applicable to orthopedic researcher. Since its development in the early 2000s, CT-RSA has benefited from breakthroughs in CT and computing technology. These advancements have allowed for the acquisition of images with higher resolution at a much lower radiation dose. As a result, the measurement precision of CT-RSA is now comparable to that of the current gold standard technology while still compatible with most ethical considerations regarding radiation exposure. In this review we present bests practices for the successful execution of CT-RSA research projects. These practices are based on experience from projects on the hip, knee, shoulder, lower back, cervical spine, foot, pelvis, and wrist.

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

BACKGROUND AND PURPOSE: 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. PATIENTS AND METHODS: 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. RESULTS: 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. CONCLUSION: 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.

BACKGROUND AND PURPOSE: 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. PATIENTS AND METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Influence of implant variations on survival of the Lubinus SP II stem: evaluation of 76,530 hips in the Swedish Arthroplasty Register, 2000-2018.

Background and purpose - Almost all prosthetic implant brands include several variations. Most studies on implant performance investigate an implant system without sub-analysis of implant attributes. We studied the influence of design variations during the last 2 decades on implant survival of the most frequently used cemented femoral stem, the Lubinus SPII, reported to the Swedish Arthroplasty Register (SHAR). Patients and methods - Between 2000 and 2018, 100,032 cemented Lubinus SP II stems had been reported to SHAR. Patients with primary osteoarthritis operated on with stem length 150 mm together with a cemented cup from the same manufacturer (n = 76,530) were included in this analysis. Primary study outcome was non-infectious stem revision. Cox regression with adjustment for age, sex, surgical approach, and year of surgery was used. Hazard rates (HR) are presented with 95% confidence intervals (CI). Results - Average follow-up was 7.6 years (SD 4.2). At 18 years the overall stem survival was 99.1 (CI 98.9-99.3). Increased revision rate was observed for stems with extra offset, when a long or an extra-long head length had been used. Smaller stem sizes, in particular the smallest stem size (01), substantially increased the rate of mechanical failure as reflected by an almost 10 times increased rate of revision compared with the standard size (2). Interpretation - In this study with larger sample size and longer follow-up than previously presented from the same register, we observed more pronounced effects of previously documented design variations. Based on our results, surgeons using the Lubinus SPII stems are advised to consider an alternative solution if a Lubinus stem size 01, Lubinus extra offset, or an extra-long head seems to be the most suitable choice at the preoperative planning.

Similar outcome with a new anteverted or a straight standard stem: a randomized study of 72 total hip arthroplasties evaluated with clinical variables, radiostereometry, and DXA up to 2 years.

Background and purpose - The anatomical uncemented stem, SP-CL (Static Physiologicus - CementLess), designed to facilitate insertion and to avoid stress concentration at solitary contact points, has been on the market since 2014 but is not well documented. We studied its clinical performance, migration, and associated bone remodeling in a randomized controlled trial, with the Corail stem as control. Patients and methods - 79 patients (80 hips) were primarily recruited and 71 patients (72 hips, 36 SP-CL, 36 Corail) attended the last follow-up at 2 years. The Oxford Hip Score (OHS) was the primary outcome. In addition, we assessed stem migration, changes in bone mineral density, and development of radiolucencies by RSA, DXA, and conventional radiography. Results - At 2 years Oxford Hip Score was similar between the SP-CL and Corail stem. At 2 years the SP-CL stems showed a median distal migration of 0.23 mm (-0.1 to 5.2) and the Corail stems of 0.11 mm (-0.4 to 4.4). The SP-CL stems showed slightly more loss of bone mineral density in Gruen region 7 (p = 0.003). Interpretation - We found no difference in clinical results between the SP-CL and the well-documented Corail stem. The same stem stability was reached between 1 and 2 years postoperatively for both stems. As a next step we think that the SP-CL stem should be studied in a multi-center setting, before being accepted for general use.

Similar risk of cancer in patients younger than 55 years with or without a total hip arthroplasty (THA): a population- based cohort study on 18,771 exposed to THA and 87,683 controls.

BACKGROUND AND PURPOSE: Concerns related to a potentially increased risk of cancer after total hip arthroplasty (THA) have frequently surfaced, especially since the novel EU medical device regulation classified cobalt as carcinogenic. We assessed the risk of cancer after THA in a nationwide cohort of patients younger than 55 years at surgery. PATIENTS AND METHODS: In this population-based longitudinal cohort study, 18,771 individuals exposed to THA were identified in the Swedish Hip Arthroplasty Registry (SHAR) and compared with 87,683 unexposed individuals who were matched by age, sex, and residence. Diagnoses, socioeconomic background, and dates of death were obtained from the Swedish Cancer Register, the National Patient Register, and Statistics Sweden. Primary outcome was the adjusted risk of any cancer after the first THA; secondary outcomes were specific cancer forms. RESULTS: We found no enhanced adjusted risk of developing any cancer, either in exposed females compared with unexposed females (hazard ratio [HR] 1.1, 95% confidence interval [CI] 0.95-1.2), or in exposed males (HR 1.1, CI 0.99-1.2). When analysing specific cancers, increased adjusted risks were found for thyroid and pancreas cancer in exposed females, and for cancer of the stomach, skin melanoma, and prostate cancer in exposed males. INTERPRETATION: This study indicates that there is no statistically significant increased overall risk of cancer in young THA-exposed patients. The potentially slightly enhanced risk for specific cancers may be due to residual confounding resulting from risk factors not accounted for and merits further investigation.

Dislocation of hemiarthroplasty after hip fracture is common and the risk is increased with posterior approach: result from a national cohort of 25,678 individuals in the Swedish Hip Arthroplasty Register.

Background and purpose - Reported revision rates due to dislocation after hemiarthroplasty span a wide range. Dislocations treated with closed reduction are rarely reported despite the fact that they can be expected to constitute most of the dislocations that occur. We aimed to describe the total dislocation rate on the national level, and to identify risk factors for dislocation.Patients and methods - We co-processed a national cohort of 25,678 patients in the Swedish Hip Arthroplasty Register, with the National Patient Register (NPR) and Statistics Sweden. Dislocation was defined as the occurrence of any ICD-10 or procedural code related to hip dislocation recorded in the NPR, with a minimum of 1-year-follow-up. In theory, all early dislocations should thereby be traced, including those treated with closed reduction only.Results - 366/13,769 (2.7%) patients operated on with direct lateral approach dislocated, compared with 850/11,834 (7.2%) of those with posterior approach. Posterior approach was the strongest risk factor for dislocation (OR = 2.7; 95% CI 2.3-3.1), followed by dementia (OR = 1.3; CI 1.1-1.5). The older the patients, the lower the risk of dislocation (OR = 0.98 per year of age; CI 0.98-1.0). Neither bipolar design nor cementless stems influenced the risk.Interpretation - The choice of posterior approach and dementia was associated with an increased dislocation risk. When hips treated with closed reduction were identified, the frequency of dislocation with use of direct lateral and posterior approach more than doubled and tripled, respectively, compared with when only revisions due to dislocation are measured.

Uncemented or cemented stems in first-time revision total hip replacement? An observational study of 867 patients including assessment of femoral bone defect size.

Background and purpose - Uncemented stems are gradually replacing cemented stems in hip revision surgery. We compared the risk of re-revision between uncemented and cemented revision stems and assessed whether the different fixation methods are used in similar femoral bone defects.Patients and methods - 867 patients operated on with uncemented or cemented stems in first-time hip revision surgery due to aseptic loosening performed 2006-2016 were identified in the Swedish Hip Arthroplasty Register. Preoperative femoral bone defect size was assessed on radiographs of all patients. Cox regression models were fitted to estimate the adjusted risk of re-revision during different postoperative time periods. Re-revision of any component for any reason, and stem re-revision, as well as risk of cause-specific re-revision was estimated.Results - Most patients in both fixation groups had Paprosky class IIIA femoral bone defects prior to surgery, but there were more severe bone defects in the cemented group. The adjusted risk of re-revision of any component for any reason was higher in patients with uncemented compared with those with cemented revision stems during the first 3 years after index surgery (hazard ratio [HR] 4, 95% confidence interval [CI] 2-9). From the 4th year onward, the risk of re-revision of any component for any reason was similar (HR 0.5, CI 0.2-1.4). Uncemented revision stems conferred a higher risk of dislocation compared with cemented stems (HR 5, CI 1.2-23) during the first 3 years.Interpretation - Although not predominantly used in more complex femoral defects, uncemented revision stem fixation confers a slightly higher risk of re-revision during the first years, but this risk is attenuated after longer follow-up.

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.

No generally increased risk of cancer after total hip arthroplasty performed due to osteoarthritis.

Previous studies on the risk of cancer after total hip arthroplasty (THA) contradict each other, and many are hampered by small cohort sizes, residual confounding, short observation times or a mix of indications underlying the THA procedure. We evaluated the risk of cancer after total hip arthroplasty due to osteoarthritis in a nationwide cohort by comparing cancer incidences in individuals exposed to total hip arthroplasty due to osteoarthritis and in unexposed, sex-, age- and residence matched individuals. To address some previous studies' shortcomings, information on comorbidity and socioeconomic background were obtained and adjusted for. We included 126,276 patients exposed to a cemented THA between 1992 and 2012, and 555,757 unexposed individuals. Follow-up started on the day of surgery for exposed individuals and respective date for matched, unexposed individuals, and ended on the day of death, emigration, censuring or December 31st, 2012, whichever came first. The Swedish Hip Arthroplasty Registry (SHAR), the Swedish Cancer Registry, the Swedish National Patient Registry and Statistics Sweden were accessed to obtain information on procedural details of the THA, cancer diagnoses, comorbidities, and socioeconomic background. The primary outcome measure was the occurrence of any cancer after the index date. Exposed individuals had a slightly lower adjusted risk of developing any cancer than unexposed individuals (hazard ratio [HR] 0.97; CI 0.95-0.99). The only cancer with a statistically significant risk increase in exposed individuals was skin melanoma (HR 1.15; CI 1.05-1.24). We attained similar risk estimates in analyses stratified by sex, in individuals with minimum 5 years of follow-up, in an analysis including individuals with a history of previous cancer, and in patients with cementless THA. In this study on a large and well-defined population with long follow-up, we found no increased overall risk of cancer after THA. These reassuring findings could be included in the guidelines on preoperative information given to THA patients.

Validity and Responsiveness of Forearm Strength Measurements in the Evaluation of Distal Radioulnar Joint Implant Arthroplasty.

PURPOSE: To assess the responsiveness of forearm strength tests and to correlate the change to grip strength and a patient-reported outcome measure used for evaluation of distal radioulnar joint (DRUJ) implant arthroplasty. METHODS: We performed a retrospective review of 18 patients treated with Herbert (n = 12) and Scheker (n = 6) DRUJ implants. Patients who had undergone the various measurements of arm and grip strength both before surgery and after a minimum follow-up of 1 year were included. Our primary aim was to compare the responsiveness of grip strength with our new methods for measuring forearm torque and lifting strength. The secondary aim was to correlate observed changes in strength measurements to change in a patient-reported outcome measure with use of the patient-reported wrist evaluation (PRWE). Measurements of grip strength, forearm torque, and lifting strength were performed with the Jamar dynamometer and the Kern and Baseline instruments. Preoperative values were compared with 1-year values. RESULTS: Standardized response mean and effect size values were higher for forearm torque than for grip strength. Change in forearm torque and lifting strength had a moderate to strong correlation with change in PRWE. The correlation between grip strength and PRWE was weak. CONCLUSIONS: Forearm torque measurements were better than grip strength in detecting changes after DRUJ arthroplasty. It also had a stronger correlation to patient-reported outcome, measured with the PRWE. CLINICAL RELEVANCE: Forearm torque testing may add further information to the evaluation of DRUJ disorders and their treatments. These tests can provide quantifiable data on the patient's ability to perform various tasks requiring physical strength.

How do EQ-5D-3L and EQ-5D-5L compare in a Swedish total hip replacement population?

Background and purpose - To better detect small changes in postoperative outcome following total hip replacement (THR), the Swedish Hip Arthroplasty Register (SHAR) has decided to change from the EQ-5D-3L (3L) to the EQ-5D-5L (5L). To enable comparison of results obtained with use of the 2 versions of EQ-5D, transferal of results between the questionnaires used is necessary. We assessed the measurement properties of the EQ-5D-5L compared with the EQ-5D-3L, preoperatively and 1-year postoperatively in a Swedish THR population.Patients and methods - Patients eligible for elective THR during 2015 in Western Sweden were invited to the study. With a 2-week separation, the 3L and 5L questionnaires were administered to patients before and 1 year after surgery. Comparing the 2 versions of the EQ-5D, we investigated redistribution of responses, ceiling and floor effects, EQ VAS correlations (Spearman's rank correlation coefficient, rs), and EQ VAS scores for different severity levels by dimension (univariable ordinary least square regression).Results - The additional severity levels of the 5L version were frequently used on both measurement occasions (preoperative mobility 5%, self-care 17%, usual activities 20%, pain 5% and anxiety 3%, postoperative mobility 6%, self-care 5%, usual activities 8%, pain 9%, and anxiety 5%). Ceiling effects of the 3L version diminished overall by 7% using the 5L version. The correlations between the 2 EQ VAS scores obtained with the 3L and 5L instruments were strong both pre- (rs = 0.71) and postoperatively (rs = 0.87). Estimated EQ VAS scores for different levels of severity were consistent for all dimensions except for the mobility dimension of the preoperative 5L version and the anxiety dimension in the postoperative 5L version.Interpretation - Our findings support that the 5L has a higher resolution than the 3L version regarding description of health-related quality of life in patients undergoing THR in Sweden. The EQ VAS scores for different levels of severity agree well between the EQ-5D versions. This could potentially be used to develop a crosswalk value set for transforming 3L to 5L responses in this patient group.

More hip complications after total hip arthroplasty than after hemi-arthroplasty as hip fracture treatment: analysis of 5,815 matched pairs in the Swedish Hip Arthroplasty Register.

Background and purpose - Total hip arthroplasty (THA) is increasing as treatment of displaced femoral neck fractures. Several studies compare hemiarthroplasty (HA) with THA, but results vary and few studies report on medical complications. We examined the outcome of THA and HA with a focus on medical complications, hip complications, and death.Patients and methods - Data from the Swedish Hip Arthroplasty Register on 30,953 acute hip fracture patients treated with cemented THA or HA in 2005-2011 were cross-matched with Statistics Sweden for socioeconomic data and with the National Patient Register for diagnostic codes representing medical complications within 180 days or hip complications within the study period. Propensity score matching was used to create comparable groups based on age, sex, income, level of education, marital status, Elixhauser index, and year of surgery. Logistic regression models were created for each outcome.Results - 81% were treated with HA, 73% and 71% were female (HA and THA respectively). Matching resulted in 2 groups of 5,815 patients each. THA was associated with fewer medical complications (OR = 0.83; 95% CI 0.76-0.91) and lower 1-year mortality (OR = 0.42; CI 0.38-0.48), but more hip complications (OR = 1.31; CI 1.20-1.43).Interpretation - THA as treatment of hip fracture was associated with more hip-related complications than HA. The results on mortality and medical complications are, rather, influenced by residual confounding than by the implant design per se. An expansive use of THAs for hip fracture treatment, at the expense of HAs, is not recommended based on our findings if hip complications are to be avoided.