Socioeconomic inequalities in patient-reported outcome measures of Dutch primary hip and knee arthroplasty patients for osteoarthritis.

OBJECTIVE: To study socio-economic inequalities in patient-reported outcomes in primary hip and knee arthroplasty (THA/TKA) patients for osteoarthritis, using two analytical techniques. METHODS: We obtained data from 44,732 THA and 30,756 TKA patients with preoperative and 12-month follow-up PROMs between 2014 and 2020 from the Dutch Arthroplasty Registry. A deprivation indicator based on neighborhood income, unemployment rate, and education level was linked and categorized into quintiles. The primary outcome measures were the EQ-5D-3L index and Oxford Hip/Knee Score (OHS/OKS) preoperative, at 12-month follow-up, and the calculated change score between these measurements. We contrasted the most and least deprived quintiles using multivariable linear regression, adjusting for patient characteristics. Concurrently, we calculated concentration indices as a non-arbitrary tool to quantify inequalities. RESULTS: Compared to the least deprived, the most deprived THA patients had poorer preoperative (EQ-5D -0.03 (95%CI -0.02, -0.04), OHS -1.26 (-0.99, -1.52)) and 12-month follow-up health (EQ-5D -0.02 (-0.01, -0.02), OHS -0.42 (-0.19, -0.65)), yet higher mean change (EQ-5D 0.02 (0.01, 0.03), OHS 0.84 (0.52, 1.16)). The most deprived TKA patients had similar results. The higher mean change among the deprived resulted from lower preoperative health in this group (confounding). After accounting for this, the most deprived patients had a lower mean change. The concentration indices showed similar inequality effects and provided information on the magnitude of inequalities over the entire socio-economic range. CONCLUSION: The most deprived THA and TKA patients have worse preoperative health, which persisted after surgery. The concentration indices allow comparison of inequalities across different outcomes (e.g., revision risk).

Machine Learning Did Not Outperform Conventional Competing Risk Modeling to Predict Revision Arthroplasty.

BACKGROUND: Estimating the risk of revision after arthroplasty could inform patient and surgeon decision-making. However, there is a lack of well-performing prediction models assisting in this task, which may be due to current conventional modeling approaches such as traditional survivorship estimators (such as Kaplan-Meier) or competing risk estimators. Recent advances in machine learning survival analysis might improve decision support tools in this setting. Therefore, this study aimed to assess the performance of machine learning compared with that of conventional modeling to predict revision after arthroplasty. QUESTION/PURPOSE: Does machine learning perform better than traditional regression models for estimating the risk of revision for patients undergoing hip or knee arthroplasty? METHODS: Eleven datasets from published studies from the Dutch Arthroplasty Register reporting on factors associated with revision or survival after partial or total knee and hip arthroplasty between 2018 and 2022 were included in our study. The 11 datasets were observational registry studies, with a sample size ranging from 3038 to 218,214 procedures. We developed a set of time-to-event models for each dataset, leading to 11 comparisons. A set of predictors (factors associated with revision surgery) was identified based on the variables that were selected in the included studies. We assessed the predictive performance of two state-of-the-art statistical time-to-event models for 1-, 2-, and 3-year follow-up: a Fine and Gray model (which models the cumulative incidence of revision) and a cause-specific Cox model (which models the hazard of revision). These were compared with a machine-learning approach (a random survival forest model, which is a decision tree-based machine-learning algorithm for time-to-event analysis). Performance was assessed according to discriminative ability (time-dependent area under the receiver operating curve), calibration (slope and intercept), and overall prediction error (scaled Brier score). Discrimination, known as the area under the receiver operating characteristic curve, measures the model's ability to distinguish patients who achieved the outcomes from those who did not and ranges from 0.5 to 1.0, with 1.0 indicating the highest discrimination score and 0.50 the lowest. Calibration plots the predicted versus the observed probabilities; a perfect plot has an intercept of 0 and a slope of 1. The Brier score calculates a composite of discrimination and calibration, with 0 indicating perfect prediction and 1 the poorest. A scaled version of the Brier score, 1 - (model Brier score/null model Brier score), can be interpreted as the amount of overall prediction error. RESULTS: Using machine learning survivorship analysis, we found no differences between the competing risks estimator and traditional regression models for patients undergoing arthroplasty in terms of discriminative ability (patients who received a revision compared with those who did not). We found no consistent differences between the validated performance (time-dependent area under the receiver operating characteristic curve) of different modeling approaches because these values ranged between -0.04 and 0.03 across the 11 datasets (the time-dependent area under the receiver operating characteristic curve of the models across 11 datasets ranged between 0.52 to 0.68). In addition, the calibration metrics and scaled Brier scores produced comparable estimates, showing no advantage of machine learning over traditional regression models. CONCLUSION: Machine learning did not outperform traditional regression models. CLINICAL RELEVANCE: Neither machine learning modeling nor traditional regression methods were sufficiently accurate in order to offer prognostic information when predicting revision arthroplasty. The benefit of these modeling approaches may be limited in this context.

The Rise of the Direct Anterior Approach: Trends, Learning Curves, and Patient Characteristics of 63,182 Primary Total Hip Arthroplasties in the Dutch Arthroplasty Register (LROI).

BACKGROUND: The use of the direct anterior approach (DAA) in total hip arthroplasty (THA) has steadily increased in the Netherlands since 2007. The aim of this study was to outline how the DAA has been implemented in the Netherlands. Moreover, we investigated the learning curve of the DAA at a hospital level, and explored patient characteristics of the DAA compared with other approaches and during the learning phase after implementing the DAA. METHODS: In this population-based cohort study, we included all primary THAs between 2007 and 2020 (n = 342,473) from the Dutch Arthroplasty Register. For hospitals implementing the DAA (n > 20), patients were categorized in 4 experience groups using the date of surgery: 1 to 50, 51 to 100, 101 to 150, or > 150. Subsequently, data from different hospitals were pooled and survival rates were calculated using Kaplan-Meier survival analyses. Adjusted revision rates were calculated using mixed Cox proportional hazard models (frailty). RESULTS: The use of the DAA gradually rose from 0.2% in 2007 to 41% of all primary THAs in 2020. A total of 64 (56%) hospitals implemented the DAA. However, not all hospitals continued using this approach. After implementation, the 5-year survival rate for the first 50 procedures was significantly lower (96% confidence interval [CI] 95.8 to 97.2) compared to >150 procedures (98% CI 97.7 to 98.1). Multivariable Cox hazard analyses demonstrated a higher risk of revision during the first 50 procedures compared with >150 procedures (hazard ratio 1.6, CI 1.3 to 2.0). CONCLUSIONS: The use of DAA for primary THA significantly increased. For hospitals implementing DAA, a considerable learning curve with increased revision risk was seen.

Socioeconomic Status Affects Patient-Reported Outcome Measures in Total Hip and Knee Arthroplasty: A Retrospective Dutch Registry Study.

BACKGROUND: To determine the association between socioeconomic status (SES) and patient-reported outcome measures in a Dutch cohort who have undergone total hip arthroplasty (THA) or total knee arthroplasty (TKA). METHODS: A retrospective national registry study of all patients who underwent primary THA or TKA between 2014 and 2020 in the Netherlands was performed. Linear mixed effects regression models were used to assess the association between SES and patient-reported outcome measures for THA and TKA patients separately. The following measures were collected: numeric rating scale for pain, Oxford Hip/Knee Score, Hip/Knee disability and Osteoarthritis Outcome Score, and the EuroQol 5-Dimensions questionnaire. Sex, age, body mass index, American Society of Anesthesiologists classification, Charnley classification, and smoking status were considered as covariates in the models. RESULTS: THA patients (n = 97,443) were on average 70 years old with a body mass index of 27.4 kg/m2, and TKA patients (n = 78,811) were on average 69 years old with a body mass index of 29.7 kg/m2. Preoperatively, patients with a lower SES undergoing THA or TKA reported more severe symptoms and lower health-related quality of life. At 1-year follow-up, they also reported lower scores and less improvement over time compared to patients with a higher SES. CONCLUSIONS: Patients with lower SES report worse symptoms when admitted for surgery and less improvement after surgery. Future research must address potentially mediating factors of the association between SES and symptom reporting such as access to surgery and rehabilitation, subjectivity in reporting, and patient expectation for THA and TKA outcomes.

Inadequate Classification of Poor Response After Total Knee Arthroplasty: A Comparative Analysis of 15 Definitions Using Data from the Dutch Arthroplasty Register and the Osteoarthritis Initiative Database.

BACKGROUND: Variations in defining poor response to total knee arthroplasty (TKA) impede comparisons of response after TKA over time and across hospitals. This study aimed to compare the prevalence, overlap, and discriminative accuracy of 15 definitions of poor response after TKA using two databases. METHODS: Data of patients one year after primary TKA from the Dutch Arthroplasty Register (LROI) (n = 12,275) and the Osteoarthritis Initiative (OAI) database (n = 204) were used to examine the prevalence, overlap (estimated by Cohen's kappa), and discriminative accuracy (sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and Youden index) of 15 different definitions of poor response after TKA. In the absence of a gold standard for measuring poor response to TKA, the numeric rating scale (NRS) satisfaction (≤ 6 'poor responder') and the global assessment of knee impact (dichotomized: ≥ 4 'poor responder') were used as anchors for assessing discriminative accuracy for the LROI and OAI dataset, respectively. These anchors were chosen based on a prior qualitative study that identified (dis)satisfaction as a central theme of poor responses to TKA by patients and knee specialists. RESULTS: The median (25th to 75th percentile) prevalence of poor responders in the examined definitions was 18.5% (14.0 to 25.5%), and the median Cohen's kappa for the overlap between pairs of definitions was 0.41 (0.32 to 0.59). Median (25th to 75th percentile) sensitivity was 0.45 (0.39 to 0.54), specificity was 0.86 (0.82 to 0.94), PPV was 0.45 (0.34 to 0.62), NPV was 0.89 (0.87 to 0.89), and the Youden index was 0.36 (0.20 to 0.43). CONCLUSION: This found a lack of overlap between different definitions of poor response to TKA. None of the examined definitions adequately classified poor responders to TKA. In contrast, the absence of a poor response could be classified with confidence.

Multiple Joint Arthroplasty in Hip and Knee Osteoarthritis Patients: A National Longitudinal Cohort Study.

BACKGROUND: Many patients suffer from osteoarthritis (OA) in multiple joints, possibly resulting in multiple joint arthroplasties (MJAs). Primarily, we determined the cumulative incidence (Cin) of MJA in hip and knee joints up to 10 years. Secondly, we calculated the mean time between the first and subsequent joint arthroplasty, and evaluated the different MJA trajectories. Lastly, we compared patient characteristics and outcomes (functionality and pain) after surgery between MJA patients and single hip arthroplasty or knee arthroplasty (HA and KA) patients. METHODS: Primary index (first) HA or KA for OA were extracted from the Dutch Arthroplasty Register. The 1, 2, 5, and 10-year Cin (including competing risk death) of MJA, mean time intervals, and MJA-trajectories were calculated and stratified for primary index HA or KA. Sex, preoperative age, and body mass index were compared using ordinal logistic regression. Outcomes, measured preoperatively, 3, 6, and 12 months postoperatively (function: Hip Disability or Knee Injury and OA Outcome Score; Pain: Numerical Rating Scale), were compared using linear regression. RESULTS: A total of 140,406 HA-patients and 140,268 KA-patients were included. One, 2, 5, and 10-year Cin for a second arthroplasty were respectively 8.9% [95% confidence interval (CI): 8.7 to 9.0], 14.3% [95% CI: 14.1 to 14.5], 24.0% [95% CI: 23.7 to 24.2], and 32.7% [95% CI: 32.2 to 33.1] after index HA, and 9.5% [95% CI: 9.4 to 9.7], 16.0% [95% CI: 15.9 to 16.2], 26.4% [95% CI: 26.1 to 26.6], and 35.8% [95% CI: 35.4 to 36.3] after index KA. The 10-year Cin for > 2 arthroplasties were small in both the index HA and KA groups. Time-intervals from first to second, third, and fourth arthroplasty were 26 [95% CI: 26.1 to 26.7], 47 [95% CI: 46.4 to 48.4], and 58 [95% CI: 55.4 to 61.1] months after index HA, and 26 [95% CI: 25.9 to 26.3], 52 [95% CI: 50.8 to 52.7], and 61 [95% CI: 58.3 to 63.4] months after index KA. There were 83% of the second arthroplasties placed in the contralateral cognate joint (ie, knee or hip). Differences in postoperative functionality and pain between MJAs and single HAs and KAs were small. CONCLUSIONS: The 10-year Cin showed that about one-third of patients received a second arthroplasty after approximately 2 years, with the majority in the contralateral cognate joint. Few patients received > 2 arthroplasties within 10 years. Being a women, having a higher body mass index, and being younger increased the odds of MJA. Postoperative outcomes were slightly negatively affected by MJA.

Time trends in case-mix and risk of revision following hip and knee arthroplasty in public and private hospitals: a cross-sectional analysis based on 476,312 procedures from the Dutch Arthroplasty Register.

BACKGROUND AND PURPOSE: This study aims to assess time trends in case-mix and to evaluate the risk of revision and causes following primary THA, TKA, and UKA in private and public hospitals in the Netherlands. METHODS: We retrospectively analyzed 476,312 primary arthroplasties (public: n = 413,560 and private n = 62,752) implanted between 2014 and 2023 using Dutch Arthroplasty Register data. We explored patient demographics, procedure details, trends over time, and revisions per hospital type. Adjusted revision risk was calculated for comparable subgroups (ASA I/II, age ≤ 75, BMI ≤ 30, osteoarthritis diagnosis, and moderate-high socioeconomic status (SES). RESULTS: The volume of THAs and TKAs in private hospitals increased from 4% and 9% in 2014, to 18% and 21% in 2022. Patients in private hospitals were younger, had lower ASA classification, lower BMI, and higher SES compared with public hospital patients. In private hospitals, age and ASA II proportion increased over time. Multivariable Cox regression demonstrated a lower revision risk for primary THA (HR 0.7, CI 0.7-0.8), TKA (HR 0.8, CI 0.7-0.9), and UKA (HR 0.8, CI 0.7-0.9) in private hospitals. After initial arthroplasty in private hospitals, 49% of THA and 37% of TKA revisions were performed in public hospitals. CONCLUSION: Patients in private hospitals were younger, had lower ASA classification, lower BMI, and higher SES com-pared with public hospital patients. The number of arthroplasties increased in private hospitals, with a lower revision risk compared with public hospitals.

Out-of-hospital opioid prescriptions after knee and hip arthroplasty: prescribers and the first prescribed opioid.

BACKGROUND: We determined the first prescribed opioid and the prescribers of opioids after knee and hip arthroplasty (KA/HA) between 2013 and 2018 in the Netherlands. We also evaluated whether the first prescribed opioid dose was associated with the total dispensed dose and long-term opioid use in the first postoperative year. METHODS: The Dutch Foundation for Pharmaceutical Statistics was linked to the Dutch Arthroplasty Register. Stratified for KA/HA, the first out-of-hospital opioid within 30 days of operation was quantified as median morphine milligram equivalent (MME). Opioid prescribers were orthopaedic surgeons, general practitioners, rheumatologists, anaesthesiologists, and other physicians. Long-term use was defined as ≥1 opioid prescription for >90 postoperative days. We used linear and logistic regression analyses adjusted for confounders. RESULTS: Seventy percent of 46 106 KAs and 51% of the 42 893 HAs were prescribed ≥1 opioid. Oxycodone increased as first prescribed opioid (from 44% to 85%) whereas tramadol decreased (64-11%), but their dosage remained stable (stronger opioids were preferred by prescribers). An increase in the first prescription of 1% MME resulted in a 0.43%/0.37% increase in total MME (KA/HA, respectively). A 100 MME increase in dose of the first dispensed opioid had a small effect on long-term use (prevalence: 25% KA, 20% HA) (odds ratio=1.02/1.01 for KA/HA, respectively). Orthopaedic surgeons increasingly prescribed the first prescription between 2013 and 2018 (44-69%). General practitioners mostly prescribed consecutive prescriptions (>50%). CONCLUSION: Oxycodone increased as first out-of-hospital prescription between 2013 and 2018. The dose of the first prescribed opioid was associated with the total dose and a small increased risk of prolonged use. First prescriptions were mostly written by orthopaedic surgeons and consecutive prescriptions by general practitioners.

A comparison of uncemented short versus standard stem length in total hip arthroplasty: results from the Dutch Arthroplasty Register.

BACKGROUND AND PURPOSE: We aimed to compare revision rates between uncemented short and standard stems in total hip arthroplasties (THAs) and the corresponding patient-reported outcome measures (PROMs). PATIENTS AND METHODS: We included all short (C.F.P., Fitmore, GTS, Metha, Nanos, Optimys, Pulchra, and Taperloc Microplasty) and standard stems in uncemented THAs registered between 2009 and 2021 in the Dutch Arthroplasty Register. Kaplan-Meier survival and multivariable Cox regression analyses were performed with overall and femoral stem revision as endpoints. RESULTS: Short stems were used in 3,352 and standard stems in 228,917 hips. 10-year overall revision rates (4.8%, 95% confidence interval [CI] 3.7-6.3 vs. 4.5%, CI 4.4-4.6) and femoral stem revision rates (3.0%, CI 2.2-4.2 vs. 2.3%, CI 2.2-2.4) were comparable for short- and standard-stem THAs. Today's predominant short stems (Fitmore and Optimys) showed short-term revision rates similar to that of standard-stem THAs. Other, less frequently used short stems had higher 10-year overall (6.3%, CI 4.7-8.5) and femoral stem (4.5%, CI 3.1-6.3) revision rates. Multivariable Cox regression also showed a higher risk for overall (HR 1.7, CI 1.0-2.9) and femoral stem revision (HR 2.0, CI 1.1-3.5) using the latter short stems compared with standard stems. An exploratory analysis of PROMs showed no difference. CONCLUSION: There was no overall difference in revision rates but a tendency toward increased revision of short stems both for the whole THA and for the stem itself. The less frequently used short stems had increased revision risk. No difference in PROMs was shown.

Revision risk by using the direct superior approach (DSA) for total hip arthroplasty compared with postero-lateral approach: early nationwide results from the Dutch Arthroplasty Register (LROI).

BACKGROUND AND PURPOSE: The direct superior approach (DSA) is a modification of the classic posterolateral approach (PLA) for total hip arthroplasty (THA), in which the iliotibial band and short external rotators are spared. The revision rate of the DSA has not been investigated previously using arthroplasty registry data. We examined the reasons and risk of revision of the DSA, compared with the direct anterior approach (DAA) and PLA. PATIENTS AND METHODS: In this population-based cohort study we included 175,543 primary THAs performed between 2014 and 2020 (PLA, n = 117,576; DAA, n = 56,626; DSA, n = 1,341). Competing risk survival analysis and multivariable Cox proportional hazard analyses, adjusted for potential confounders, were performed. RESULTS: After 3 years, crude revision rates due to any reason were 2.1% (95% confidence interval [CI] 1.3-3.3) for DSA, and 2.9% (CI 2.8-3.0) for PLA. Crude dislocation revision rates were 0.3% (CI 0.1-0.8) for DSA, versus 1.0% (CI 0.9-1.0) for PLA. Dislocation revision rate for DSA did not differ from DAA (0.3% [CI 0.2-0.3]). Multivariable Cox regression analysis demonstrated no overall difference in revision rates for the DSA (HR 0.6 [CI 0.4-1.09) compared with the PLA. Lower risk of revision due to dislocation was found in patients operated on through the DSA (HR 0.3 [0.1-0.9]) compared with the PLA. CONCLUSION: Early nationwide results suggest that the DSA for total hip arthroplasty seems to show a tendency towards a lower risk of revision for dislocation but no overall reduced revision risk compared with the PLA.

Short-stem hip arthroplasty in Australia and the Netherlands: a comparison of 12,680 cases between the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) and the Dutch Arthroplasty Register (LROI).

BACKGROUND AND PURPOSE: We compared the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) and the Dutch Arthroplasty Register (LROI) regarding patient, prosthesis, and procedure characteristics as well as revision rates for uncemented short-stem total hip arthroplasties (THAs). PATIENTS AND METHODS: All THAs with an uncemented short-stemmed femoral component performed between 2009 and 2021 were included from the AOANJRR (n = 9,328) and the LROI (n = 3,352). Kaplan-Meier survival analyses and multivariable Schemper's weighted Cox regression analyses with data from 2009-2021 and 2015-2021 were performed with overall revision as endpoint. RESULTS: In Australia, the proportion of male patients (51% vs. 40%), patients with ASA III-IV score (30% vs. 3.7%), BMI ≥ 30.0 (39% vs. 19%), and femoral heads of 36 mm (58% vs. 20%) were higher than in the Netherlands. Short-stem THAs in Australia and the Netherlands had comparable 10-year revision rates (3.4%, 95% confidence interval [CI] 2.9-4.0 vs. 4.8%, CI 3.7-6.3). Multivariable Cox regression analyses with data from 2009-2021 showed a higher risk for revision of short-stem THAs performed in the Netherlands (HR 1.8, CI 1.1-2.8), whereas the risk for revision was comparable (HR 0.9, CI 0.5-1.7) when adjusted for more potential confounders using data from 2015-2021. CONCLUSION: Short-stem THAs in Australia and the Netherlands have similar crude and adjusted revision rates, which are acceptable at 10 years of follow-up.

No difference in 1-year improvement of patient-reported physical functioning and pain between resurfaced and unresurfaced patellae: analysis of 17,224 primary total knee arthroplasties in the Dutch Arthroplasty Register.

BACKGROUND AND PURPOSE: Whether or not to resurface the patella during primary total knee arthroplasty (TKA) remains controversial. We aimed to investigate the association between patellar resurfacing and patient-reported outcome measure (PROM) improvement 1 year postoperatively in terms of physical functioning and pain following TKA. PATIENTS AND METHODS: We performed an observational study using the Dutch Arthroplasty Register on prospectively collected PROM data (n = 17,224, years 2014-2019). Preoperative and 1-year PROM pain scores (NRS at rest; during activity) and physical functioning scores (KOOS-PS, OKS) were examined. Stratification was performed for cruciate-retaining (CR) and posterior-stabilized (PS) and for the 4 most frequently used TKA implants in the Netherlands (Nexgen, Genesis II, PFC/Sigma, Vanguard) using multivariable linear regression adjusting for age, ASA classification, preoperative general health (EQ VAS), and preoperative PROMs. RESULTS: 4,525 resurfaced and 12,699 unresurfaced patellae in TKA were analyzed. Overall, no significant difference in 1-year PROM improvement was found between the 2 groups. In CR TKAs, resurfacing resulted in less improvement in KOOS-PS and OKS (adjusted difference between groups (B) -1.68, 95% confidence interval (CI) -2.86 to -0.50 and B -0.94, CI -1.57 to -0.31. Fewer improvements for patellar resurfacing in TKA were found for the Genesis TKA on NRS pain at rest (B -0.23, CI-0.40 to -0.06) and Oxford knee score (B -1.61, CI -2.24 to -0.98). CONCLUSION: No significant differences were found in 1-year improvement of physical functioning and pain between TKA with resurfaced and unresurfaced patellae.

No difference in the use of revision components and rerevision rate in conversion to total knee replacement following Oxford Partial Knee Microplasty Instrumentation: a registry study of 529 conversions.

BACKGROUND AND PURPOSE: Microplasty Instrumentation was introduced to improve Oxford Mobile Partial Knee placement and preserve tibial bone in partial knee replacement (PKR). This might therefore reduce revision complexity. We aimed to assess the difference in use of revision total knee replacement (TKR) tibial components in failed Microplasty versus non-Microplasty instrumented PKRs. PATIENTS AND METHODS: Data on 529 conversions to TKR (156 Microplasty instrumented and 373 non-Microplasty instrumented PKRs) from the Dutch Arthroplasty Register (LROI) between 2007 and 2019 was used. The primary outcome was the difference in use of revision TKR tibial components during conversion to TKR, which was calculated with a univariable logistic regression analysis. The secondary outcomes were the 3-year re-revision rate and hazard ratios calculated with Kaplan-Meier and Cox regression analyses. RESULTS: Revision TKR tibial components were used in 29% of the conversions to TKR after failed Microplasty instrumented PKRs and in 24% after failed non-Microplasty instrumented PKRs with an odds ratio of 1.3 (CI 0.86-2.0). The 3-year re-revision rates were 8.4% (CI 4.1-17) after conversion to TKR for failed Microplasty and 11% (CI 7.8-15) for failed non-Microplasty instrumented PKRs with a hazard ratio of 0.77 (CI 0.36-1.7). CONCLUSION: There was no difference in use of revision tibial components for conversion to TKR or in re-revision rate after failed Microplasty versus non-Microplasty instrumented PKRs nor in the 3-year revision rate.

No clinically relevant difference in patient-reported outcomes between the direct superior approach and the posterolateral or anterior approach for primary total hip arthroplasty: analysis of 37,976 primary hip arthroplasties in the Dutch Arthroplasty Registry.

BACKGROUND AND PURPOSE: The direct superior approach (DSA) is a modification of the posterolateral approach (PLA) for total hip arthroplasty (THA). Patient-reported outcome measures (PROMs) of the DSA have not been investigated previously using nationwide data. Our aim was to assess PROMs after THA using the DSA compared with the PLA and, secondarily, with the anterior approach (DAA). PATIENTS AND METHODS: In this population-based cohort study we included 37,976 primary THAs performed between 2014 and 2020 (PLA: n = 22,616; DAA: n = 15,017; DSA: n = 343) using Dutch Arthroplasty Registry data. PROMs (NRS pain, EQ-5D, HOOS-PS, and OHS) were measured preoperatively, and at 3 and 12 months postoperatively. Repeated measurements were analyzed using mixed-effects models, adjusted for confounders, to investigate the association between surgical approach and PROMs over time. RESULTS: From baseline to 3 and 12 months, improvements for NRS pain scores, EQ-5D, and OHS were comparable for the DSA compared with the PLA or DAA. No difference was found in HOOS-PS improvement 3 months postoperatively between DSA and PLA (-0.2, 95% confidence interval [CI] -2.4 to 1.9) and between DSA and DAA (-1.7, CI -3.9 to 0.5). At 12 months postoperatively, patients in the DSA group had improved -2.8 points (CI -4.9 to -0.6) more in HOOS-PS compared with the DAA, but not with the PLA group (-1.0, CI -3.2 to 1.1). CONCLUSION: Our study showed no clinically meaningful differences between the DSA and either PLA or DAA.

The use of antibiotic-loaded bone cement and systemic antibiotic prophylactic use in 2,971,357 primary total knee arthroplasties from 2010 to 2020: an international register-based observational study among countries in Africa, Europe, North America, and Oceania.

BACKGROUND AND PURPOSE: Antibiotic-loaded bone cement (ALBC) and systemic antibiotic prophylaxis (SAP) have been used to reduce periprosthetic joint infection (PJI) rates. We investigated the use of ALBC and SAP in primary total knee arthroplasty (TKA). PATIENTS AND METHODS: This observational study is based on 2,971,357 primary TKAs reported in 2010-2020 to national/regional joint arthroplasty registries in Australia, Denmark, Finland, Germany, Italy, the Netherlands, New Zealand, Norway, Romania, South Africa, Sweden, Switzerland, the UK, and the USA. Aggregate-level data on trends and types of bone cement, antibiotic agents, and doses and duration of SAP used was extracted from participating registries. RESULTS: ALBC was used in 77% of the TKAs with variation ranging from 100% in Norway to 31% in the USA. Palacos R+G was the most common (62%) ALBC type used. The primary antibiotic used in ALBC was gentamicin (94%). Use of ALBC in combination with SAP was common practice (77%). Cefazolin was the most common (32%) SAP agent. The doses and duration of SAP used varied from one single preoperative dosage as standard practice in Bolzano, Italy (98%) to 1-day 4 doses in Norway (83% of the 40,709 TKAs reported to the Norwegian arthroplasty register). CONCLUSION: The proportion of ALBC usage in primary TKA varies internationally, with gentamicin being the most common antibiotic. ALBC in combination with SAP was common practice, with cefazolin the most common SAP agent. The type of ALBC and type, dose, and duration of SAP varied among participating countries.

Do Dual-mobility Cups Reduce Revision Risk in Femoral Neck Fractures Compared With Conventional THA Designs? An International Meta-analysis of Arthroplasty Registries.

BACKGROUND: Dual-mobility cups in THA were designed to reduce prosthesis instability and the subsequent risk of revision surgery in high-risk patients, such as those with hip fractures. However, there are limited data from clinical studies reporting a revision benefit of dual-mobility over conventional THA. Collaboration between anthroplasty registries provides an opportunity to describe international practice variation and compare between-country, all-cause revision rates for dual-mobility and conventional THA. QUESTIONS/PURPOSES: We summarized observational data from multiple arthroplasty registries for patients receiving either a dual-mobility or conventional THA to ask: (1) Is dual-mobility use associated with a difference in risk of all-cause revision surgery compared with conventional THA? (2) Are there specific patient characteristics associated with dual-mobility use in the hip fracture population? (3) Has the use of dual-mobility constructs changed over time in patients receiving a THA for hip fracture? METHODS: Six member registries of the International Society of Arthroplasty Registries (from Australia, Denmark, Sweden, the Netherlands, the United Kingdom, and the United States) provided custom aggregate data reports stratified by acetabular cup type (dual-mobility or conventional THA) in primary THA for hip fracture between January 1, 2002, and December 31, 2019; surgical approach; and patient demographic data (sex, mean age, American Society of Anesthesiologists class, and BMI). The cumulative percent revision and mortality were calculated for each registry. To determine a global hazard ratio of all-cause revision for dual-mobility compared with conventional THA designs, we used a pseudoindividual patient data approach to pool Kaplan-Meier prosthesis revision data from each registry and perform a meta-analysis. The pseudoindividual patient data approach is a validated technique for meta-analysis of aggregate time-to-event survival data, such as revision surgery, from multiple sources. Data were available for 15,024 dual-mobility THAs and 97,200 conventional THAs performed for hip fractures during the study period. RESULTS: After pooling of complete Kaplan-Meier survival data from all six registries, the cumulative percent revision for conventional THA was 4.3% (95% confidence interval [CI] 4.2% to 4.5%) and 4.7% (95% CI 4.3% to 5.3%) for dual-mobility THA at 5 years. We did not demonstrate a lower risk of all-cause revision for patients receiving dual-mobility over conventional THA designs for hip fracture in the meta-analysis once between-registry differences were adjusted for (HR 0.96 [95% CI 0.86 to 1.06]). A lower proportion of dual-mobility procedures were revised for dislocation than conventional THAs (0.9% versus 1.4%) but a higher proportion were revised for infection (1.2% versus 0.8%). In most registries, a greater proportion of dual-mobility THA patients were older, had more comorbidities, and underwent a posterior approach compared with conventional THA (p < 0.001). The proportion of dual-mobility THA used to treat hip fractures increased in each registry over time and constituted 21% (2438 of 11,874) of all THA procedures in 2019. CONCLUSION: The proportion of dual-mobility THAs in patients with hip fractures increased over time, but there was large variation in use across countries represented here. Dual-mobility cups were not associated with a reduction in the overall risk of revision surgery in patients with hip fractures. A randomized controlled trial powered to detect the incidence of dislocation and subsequent revision surgery is required to clarify the efficacy of dual-mobility cups to treat hip fractures. LEVEL OF EVIDENCE: Level III, therapeutic study.

Mismatch in Capture of Periprosthetic Joint Infections Between the Dutch Arthroplasty Register (LROI) and a Detailed Regional Periprosthetic Joint Infection Registry.

BACKGROUND: National arthroplasty registries are important sources for periprosthetic joint infection (PJI) data and report an average incidence ranging from 0.5% to 2.0%. However, studies have shown that PJI incidence in national arthroplasty registries may be underestimated. Therefore, the incidence of PJI in the Dutch Arthroplasty Register (LROI) was evaluated. METHODS: We matched revisions due to infection within 90 days of index procedure in the LROI database (prospectively registered in 2014-2018) with acute PJI cases registered in a Regional Infection Cohort (RIC) and vice versa. The RIC comprised of 1 university hospital, 3 large orthopedic teaching hospitals and 4 general district hospitals, representing 11.3% of all Dutch arthroplasty procedures with a similar case mix. RESULTS: From the 352 acute PJIs in the RIC, 166 (47%) were registered in the LROI. Of the 186 confirmed PJI cases not registered in the LROI, 51% (n = 95) were a unregistered Debridement, Antibiotics, and Implant Retention procedure without component exchange. The remaining missing PJI cases (n = 91, 49%) were of administrative origin. The acute PJI incidence in the RIC was 1%, compared to a 0.6% incidence of revision <90 days due to infection from LROI data. CONCLUSION: Besides unregistered Debridement, Antibiotics, and Implant Retention procedures without component exchange, administrative errors are an important source of missing PJI data for the LROI, leading to underestimation of PJI incidence in the Netherlands. A national arthroplasty complication registry, linked to the LROI, might decrease the number of missing PJI cases. Although our study concerns Dutch data, it supports the scarce literature on PJI incidence obtained from national arthroplasty registries, which also reports an underestimation.

Patient-reported outcome of 95% of young patients improves after primary total hip arthroplasty: identification of 3 recovery trajectories in 3,207 patients younger than 55 years from the Dutch Arthroplasty Register.

BACKGROUND AND PURPOSE: Little is known about the outcome after receiving total hip arthroplasty (THA), specifically in young patients. We identified different recovery trajectories in young patients using data from the Dutch Arthroplasty Register (LROI). We also explored whether risk factors commonly associated with functional outcome were associated with recovery trajectory. PATIENTS AND METHODS: We used HOOS-PS score data up to 1 year postoperatively from the LROI from all patients younger than 55 years who received a primary THA between 2014 and 2019. To investigate whether different recovery trajectories could be distinguished, we performed latent class growth analysis (LCGA). Subsequently, we used multinomial logistic regression analyses to explore factors associated with class membership. RESULTS: 3,207 patients were included. LCGA identified 3 groups of patients: optimal responders (75%), good responders (21%), and poor responders (4.7%). Female sex (RR 1.1; 95% CI 1.1-1.1), ASA II (RR 1.1; CI 1.0-1.1), ASA III-IV (RR 1.1; CI 1.0-1.2), smoking (RR 1.1; CI 1.0-1.1), cemented fixation (RR 1.2; CI 1.1-1.2), and a 22-28 mm head diameter (RR 1.1; CI 1.0-1.2) were associated with "good responder" class membership. ASA II (RR 1.1; 1.0-1.2), ASA III-IV (RR 1.2; 1.1-1.3), smoking (RR 1.2; CI 1.1-1.2), and hybrid fixation (RR 1.2; CI 1.0-1.2) were associated with "poor responder" class membership. INTERPRETATION: 3 recovery trajectories could be identified. Female sex, higher ASA classifications, smoking, cemented or hybrid fixation, and small head diameter were associated with a suboptimal result after primary THA in young patients. These findings can aid in the process to determine which patients are at risk of a suboptimal outcome.

Comparable mortality but higher revision rate after uncemented compared with cemented total hip arthroplasties in patients 80 years and older: report of 43,053 cases of the Dutch Arthroplasty Register.

Background and purpose - Mortality and revision risks are important issues during shared decision-making for total hip arthroplasty (THA) especially in elderly patients. We examined mortality and revision rates as well as associated patient and prosthesis factors in primary THA for osteoarthritis (OA) in patients ≥ 80 years in the Netherlands. Patients and methods - We included all primary THAs for OA in patients ≥ 80 years in the period 2007-2019. Patient mortality and prosthesis revision rates were calculated using Kaplan-Meier survival analyses. Risk factors for patient mortality and prosthesis revision were analyzed using multivariable Cox regression analysis adjusted for age, sex, ASA class, fixation method, head size, and approach. Results - Mortality was 0.2% at 7 days, 0.4% at 30 days, 2.7% at 1 year, and 20% at 5 years. Mortality was higher in males and higher ASA class, but did not differ between fixation methods. The 1-year revision rate was 1.6% (95% CI 1.5-1.7) and 2.6% (CI 2.5-2.7) after 5 years. Multivariable Cox regression analysis showed a higher risk of revision for uncemented (hazard ratio [HR] 1.6; CI 1.4-1.8) and reverse hybrid THAs (HR 2.9; CI 2.1-3.8) compared with cemented THAs. Periprosthetic fracture was the most frequently registered reason for revision in uncemented THAs. Interpretation - Mortality is comparable but revision rate is higher after uncemented compared with cemented THA in patients 80 years and older, indicating that cemented THA might be a safer option in this patient group.

A more comprehensive evaluation of quality of care after total hip and knee arthroplasty: combining 4 indicators in an ordered composite outcome.

Background and purpose - Most arthroplasty registers give hospital-specific feedback on revision rates after total hip and knee arthroplasties (THA/TKA). However, due to the low number of events per hospital, multiple years of data are required to reliably detect worsening performance, and any single indicator provides only part of the quality of care delivered. Therefore, we developed an ordered composite outcome including revision, readmission, complications, and long length-of-stay (LOS) for a more comprehensive view on quality of care and assessed the ability to reliably differentiate between hospitals in their performance (rankability) with fewer years of data. Methods - All THA and TKA performed between 2017 and 2019 in 20 Dutch hospitals were included. All combinations of the 4 indicators were ranked from best to worst to create the ordinal composite outcome for THA and TKA separately. Between-hospital variation for the composite outcome was compared with individual indicators standardized for case-mix differences, and we calculated the statistical rankability using fixed and random effects models. Results - 22,908 THA and 20,423 TKA were included. Between-hospital variation for the THA and TKA composite outcomes was larger when compared with revision, readmission, and complications, and similar to long LOS. Rankabilities for the composite outcomes were above 80% even with 1 year of data, meaning that largely true hospital differences were detected rather than random variation. Interpretation - The ordinal composite outcome gives a more comprehensive overview of quality of delivered care and can reliably differentiate between hospitals in their performance using 1 year of data, thereby allowing earlier introduction of quality improvement initiatives.