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Background: The ability to identify which patients are at a greater risk of early revision knee arthroplasty has important practical and resource implications. Many international arthroplasty registries administer patient-reported outcome measures (PROMs) to provide a holistic assessment of pain, function, and quality of life. However, few PROM scores have been evaluated as potential indicators of early revision knee arthroplasty, and earlier studies have largely focused on knee-specific measures Questions/purposes: This national registry-based study asked: (1) Which 6-month postoperative knee-specific and generic PROM scores are associated with early revision knee arthroplasty (defined as revision surgery performed 6 to 24 months after the primary procedure)? (2) Is a clinically important improvement in PROM scores (based on thresholds for the minimal important change) after primary knee arthroplasty associated with a lower risk of early revision? Methods: Preoperative and 6-month postoperative PROM scores for patients undergoing primary knee arthroplasty were sourced from the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) and Arthroplasty Clinical Outcomes Registry National. Between January 2013 and December 2020, PROM data were available for 19,402 primary total knee arthroplasties; these data were linked to AOANJRR data on revision knee arthroplasty. Of these, 3448 procedures were excluded because they did not have 6-month PROM data, they had not reached the 6-month postoperative point, they had died before 24 months, or they had received revision knee arthroplasty before the 6-month PROMs assessment. After these exclusions, data were analyzed for 15,954 primary knee arthroplasties. Associations between knee-specific (knee pain, Oxford Knee Score, and 12-item Knee injury and Osteoarthritis Outcome Score [KOOS-12]) or generic PROM scores (5-level EuroQol quality of life instrument [EQ-5D], EQ VAS, perceived change, and satisfaction) and revision surgery were explored using t-tests, chi-square tests, and regression models. Ninety-four revision procedures were performed at 6 to 24 months, most commonly for infection (39% [37 procedures]). The early revision group was younger than the unrevised group (mean age 64 years versus 68 years) and a between-group difference in American Society of Anesthesiologists (ASA) grade was noted. Apart from a small difference in preoperative low back pain for the early revision group (mean low back pain VAS 4.2 points for the early revision group versus 3.3 points for the unrevised group), there were no between-group differences in preoperative knee-specific or generic PROM scores on univariate analysis. As the inclusion of ASA grade or low back pain score did not alter the model results, the final multivariable model included only the most clinically plausible confounders (age and gender) as covariates. Multivariable models (adjusting for age and gender) were also used to examine the association between a clinically important improvement in PROM scores (based on published thresholds for minimal important change) and the likelihood of early revision. Results: After adjusting for age and gender, poor postoperative knee pain, Oxford, KOOS-12, EQ-5D, and EQ VAS scores were all associated with early revision. A one-unit increase (worsening) in knee pain at 6 months was associated with a 31% increase in the likelihood of revision (RR 1.31 [95% confidence interval (CI) 1.19 to 1.43]; p < 0.001). Reflecting the reversed scoring direction, a one-unit increase (improvement) in Oxford or KOOS-12 score was associated with a 9% and 5% reduction in revision risk, respectively (RR for Oxford: 0.91 [95% CI 0.90 to 0.93]; p < 0.001; RR for KOOS-12 summary: 0.95 [95% CI 0.94 to 0.97]; p < 0.001). Patient dissatisfaction (RR 6.8 [95% CI 3.7 to 12.3]) and patient-perceived worsening (RR 11.7 [95% CI 7.4 to 18.5]) at 6 months were also associated with an increased likelihood of early revision. After adjusting for age and gender, patients who did not achieve a clinically important improvement in PROM scores had a higher risk of early revision (RR 2.9 for the knee pain VAS, RR 4.2 for the Oxford Knee Score, RR 6.3 to 8.6 for KOOS-12, and RR 2.3 for EQ-5D) compared with those who did (reference group). Conclusion: Knee-specific and generic PROM scores offer an efficient approach to identifying patients at greater risk of early revision surgery, using either the 6-month score or the magnitude of improvement. These data indicate that surgeons can use single- and multi-item measures to detect a patient-perceived unsuccessful surgical outcome at 6 months after primary knee arthroplasty. Surgeons should be alert to poor PROM scores at 6 months or small improvements in scores (for example, less than 2 points for knee pain VAS or less than 10.5 points for Oxford Knee Score), which signal a need for direct patient follow-up or expedited clinical review. Level of Evidence: Level III, therapeutic study. Refereed/Peer-reviewed

This article was updated on August 17, 2022, because of previous errors, which were discovered after the preliminary version of the article was posted online. On page 1462, in the first sentence of the Abstract section entitled "Results," the phrase that had read "and 36-mm heads had fewer dislocations than 28-mm (HR = 0.33 [95% CI, 0.16 to 0.68]; p = 0.003), but more dislocations than 32-mm heads (HR for2 weeks = 2.25 [95% CI, 1.13 to 4.49]; p = 0.021)" now reads "and 36-mm heads had fewer dislocations than 28-mm (HR = 0.33 [95% CI, 0.16 to 0.68]; p = 0.003) and 32-mm heads (HR for ≥2 weeks = 0.44 [95% CI, 0.22 to 0.88]; p = 0.021)." On page 1468, in the last sentence of the section entitled "Acetabular Components with a Diameter of51 mm," the phrase that had read "and HR for ≥2 weeks = 2.25 [95% CI, 1.13 to 4.49; p = 0.021]) ( Fig. 3 )" now reads "and HR for ≥2 weeks = 0.44 [95% CI, 0.22 to 0.88; p = 0.021]) ( Fig. 3 )." Finally, on page 1466, in the upper right corner of Figure 3 , under "32mm vs 36mm," the second line that had read "2Wks+: HR=2.25 (1.13, 4.49), p=0.021" now reads "2Wks+: HR=0.44 (0.22, 0.88), p= 0.021."The acetabular component diameter can influence the choice of femoral head size in total hip arthroplasty (THA). We compared the rates of revision by femoral head size for different acetabular component sizes. Data from the Australian Orthopaedic Association National Joint Replacement Registry were analyzed for patients undergoing primary THA for a diagnosis of osteoarthritis from September 1999 to December 2019. Acetabular components were stratified into quartiles by size:51 mm, 51 to 53 mm, 54 to 55 mm, and 56 to 66 mm. Femoral head sizes of 28 mm, 32 mm, and 36 mm were compared for each cup size. The primary outcome was the cumulative percent revision (CPR) for all aseptic causes and for dislocation. The results were adjusted for age, sex, femoral fixation, femoral head material, year of surgery, and surgical approach and were stratified by femoral head material. For acetabular components of51 mm, 32-mm (hazard ratio [HR] = 0.75 [95% confidence interval (CI), 0.57 to 0.97]; p = 0.031) and 36-mm femoral heads (HR = 0.58 [95% CI, 0.38 to 0.87]; p = 0.008) had a lower CPR for aseptic causes than 28-mm heads; and 36-mm heads had fewer dislocations than 28-mm (HR = 0.33 [95% CI, 0.16 to 0.68]; p = 0.003), and 32-mm heads (HR for ≥2 weeks = 0.44 [95% CI, 0.22 to 0.88]; p = 0.021). For 51 to 53-mm, 54 to 55-mm, and 56 to 66-mm-diameter acetabular components, there was no difference in the CPR for aseptic causes among head sizes. A femoral head size of 36 mm had fewer dislocations in the first 2 weeks than a 32-mm head for the 51 to 53-mm acetabular components (HR for2 weeks = 3.79 [95% CI, 1.23 to 11.67]; p = 0.020) and for the entire period for 56 to 66-mm acetabular components (HR = 1.53 [95% CI, 1.05 to 2.23]; p = 0.028). The reasons for revision differed for each femoral head size. There was no difference in the CPR between metal and ceramic heads. There is no clear advantage to any single head size except with acetabular components of51 mm, in which 32-mm and 36-mm femoral heads had lower rates of aseptic revision. If stability is prioritized, 36-mm femoral heads may be indicated. Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

Refereed/Peer-reviewed Background: The objective is to determine whether body mass index is associated with patient-reported expectations and well-being before primary total hip or total knee arthroplasty, and patient-reported outcomes 6 months after surgery. Methods: Data were obtained from the Australian Orthopaedic Association National Joint Replacement Registry. Outcome measures included pre-operative expectations for post-operative mobility, joint pain and health, pre- and post-operative EQ-5D-5L, EQ-VAS, Oxford Hip/Knee Scores and joint pain scales, and post-operative perceived change and perceived satisfaction. Associations with BMI were assessed using chi-square tests, analysis of variance and Linear Mixed Models equations. Results: Data were available for 12 816 primary THA patients and 20 253 primary TKA patients. Pre-operatively, patients in higher BMI categories were significantly more likely to expect ongoing problems with mobility, more joint pain and poorer health following surgery (P

Aims National joint registries under-report revisions for periprosthetic joint infection (PJI). We aimed to validate PJI reporting to the Australian Orthopaedic Association National Joint Arthroplasty Registry (AOANJRR) and the factors associated with its accuracy. We then applied these data to refine estimates of the total national burden of PJI. Methods A total of 561 Australian cases of confirmed PJI were captured by a large, prospective observational study, and matched to data available for the same patients through the AOANJRR. Results In all, 501 (89.3%) cases of PJI recruited to the prospective observational study were successfully matched with the AOANJRR database. Of these, 376 (75.0%) were captured by the registry, while 125 (25.0%) did not have a revision or reoperation for PJI recorded. In a multivariate logistic regression analysis, early (within 30 days of implantation) PJIs were less likely to be reported (adjusted odds ratio (OR) 0.56; 95% confidence interval (CI) 0.34 to 0.93; p = 0.020), while two-stage revision procedures were more likely to be reported as a PJI to the registry (OR 5.3 (95% CI 2.37 to 14.0); p ≤ 0.001) than debridement and implant retention or other surgical procedures. Based on this data, the true estimate of the incidence of PJI in Australia is up to 3,900 cases per year. Conclusion In Australia, infection was not recorded as the indication for revision or reoperation in one-quarter of those with confirmed PJI. This is better than in other registries, but suggests that registry-captured estimates of the total national burden of PJI are underestimated by at least one-third. Inconsistent PJI reporting is multifactorial but could be improved by developing a nested PJI registry embedded within the national arthroplasty registry. Cite this article: Bone Jt Open 2022;3(5):367–373.

For patient-reported outcome measures (PROMs) to provide meaningful information to support clinical care, we need to understand the magnitude of change that matters to patients. The aim of this study was to estimate minimal clinically important changes (MCICs) for the 12-item Hip disability and Osteoarthritis Outcome Score (HOOS-12) and Knee injury and Osteoarthritis Outcome Score (KOOS-12) among people undergoing joint replacement for osteoarthritis.Individual-level data from the Australian Orthopaedic Association National Joint Replacement Registry's pilot PROMs program were used for this analysis. Preoperative and 6-month postoperative HOOS-12 and KOOS-12 domain and summary impact scores plus a rating of patient-perceived change after surgery (on a 5-point scale ranging from "much worse" to "much better") were available. Three anchor-based approaches-mean change, receiver operating characteristics (ROC) based on Youden's J statistic, and predictive modeling using a binary logistic regression model-were used to calculate MCICs based on patient-perceived change.Data were available for 1,490 patients treated with total hip replacement (THR) (mean age, 66 years; 54% female) and 1,931 patients treated with total knee replacement (TKR) (mean age, 66 years; 55% female). Using the mean change method, the MCIC ranged from 24.0 to 27.5 points for the HOOS-12 and 17.5 to 21.8 points for the KOOS-12. The ROC analyses generated comparable MCIC values (28.1 for HOOS-12 and a range of 15.6 to 21.9 for KOOS-12) with high sensitivity and specificity. Lower estimates were derived from predictive modeling following adjustment for the proportion of improved patients (range, 15.7 to 19.2 for HOOS-12 and 14.2 to 16.5 for KOOS-12).We report MCIC values for the HOOS-12 and KOOS-12 instruments that we derived using 3 different methods. As estimates obtained using predictive modeling can be adjusted for the proportion of improved patients, these may be the most clinically applicable. These MCIC values can be used to interpret important changes in pain, function, and quality of life from the patient's perspective.Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Background A socioeconomic gradient exists in the utilisation of total hip replacements (THR) and total knee replacements (TKR) for osteoarthritis. However, the relations between socioeconomic status (SES) and time to THR or TKR is unknown. Aim To describe the association between SES and time to THR and TKR. Methods 1072 older-adults residing in Tasmania, Australia were studied. Incident primary THR and TKR were determined by data linkage to the Australian Orthopaedic Association National Joint Replacement Registry. At baseline, each participant's area-level SES was determined by the Index of Relative Socioeconomic Advantage and Disadvantage (IRSAD), from the Australian Bureau of Statistics' 2001 census data. IRSAD was analysed in two ways; 1) categorised into quartiles, whereby quartile 1 represented the most socioeconomically disadvantaged group, 2) the cohort dichotomised at the quartile 1 cut-point. Results The mean age was 63.0 (±7.5) years, and 51% were women. Over the median follow-up of 12.9 (Interquartile range: 12.2-13.9) years, 56 (5%) participants had a THR, and 79 (7%) had a TKR. Compared to the most disadvantaged quartile, less disadvantaged participants were less likely to have a THR (i.e. less disadvantaged participants had a longer time to THR) (HR: 0.56, 95% CI 0.32, 1.00) but not TKR (HR: 0.90, 95% CI 0.53, 1.54). However, the former became non-significant after adjustment for pain and radiographic osteoarthritis, suggesting that the associations may be mediated by these factors. Conclusions This study suggests that time to joint replacement was determined according to the symptoms/need of the participants rather than their SES. This article is protected by copyright. All rights reserved.

Background Highly porous-coated titanium acetabular components have a high coefficient of friction and ultraporous surfaces to enhance bone ingrowth and osseointegration in total hip arthroplasty (THA). There have been concerns with the development of early radiolucent lines and aseptic loosening of highly porous acetabular components. It is unclear whether these concerns relate to a specific implant or the entire class. The aim of this study is to compare the revision rates for aseptic loosening of highly porous acetabular combinations in primary THA using data from a large joint replacement registry. Methods Data were retrieved from the Australian Orthopedic Association National Joint Replacement Registry for the study period September 1999 to December 2019. All primary THA procedures recorded and performed for osteoarthritis using the most common combinations for each highly porous acetabular component with highly cross-linked polyethylene and a 32-mm or 36-mm femoral head were included. The primary outcome measure was revision for aseptic loosening of the acetabular component. Results were adjusted for patient age and gender. Results There were 20,993 primary THA procedures performed for osteoarthritis using a highly porous acetabular component across 6 combinations. Relative to the POLARSTEM/R3 (StikTite), the Exeter V40/Tritanium had a significantly higher risk of revision for aseptic loosening of the acetabular component (hazard ratio 0.21, 95% confidence interval 0.06-0.74, P = .014). There was no difference between any other highly porous acetabular component combination and no late revisions for aseptic loosening. Conclusion Highly porous-coated titanium acetabular components have low rates of aseptic loosening with long-term follow-up. A difference between components may exist. Level of Evidence Level III.

ImportanceThere remains a lack of randomized trials investigating aspirin monotherapy for symptomatic venous thromboembolism (VTE) prophylaxis following total hip arthroplasty (THA) or total knee arthroplasty (TKA).ObjectiveTo determine whether aspirin was noninferior to enoxaparin in preventing symptomatic VTE after THA or TKA.Design, Setting, and ParticipantsCluster-randomized, crossover, registry-nested trial across 31 hospitals in Australia. Clusters were hospitals performing greater than 250 THA or TKA procedures annually. Patients (aged ≥18 years) undergoing hip or knee arthroplasty procedures were enrolled at each hospital. Patients receiving preoperative anticoagulation or who had a medical contraindication to either study drug were excluded. A total of 9711 eligible patients were enrolled (5675 in the aspirin group and 4036 in the enoxaparin group) between April 20, 2019, and December 18, 2020. Final follow-up occurred on August 14, 2021.InterventionsHospitals were randomized to administer aspirin (100 mg/d) or enoxaparin (40 mg/d) for 35 days after THA and for 14 days after TKA. Crossover occurred after the patient enrollment target had been met for the first group. All 31 hospitals were initially randomized and 16 crossed over prior to trial cessation.Main Outcomes and MeasuresThe primary outcome was symptomatic VTE within 90 days, including pulmonary embolism and deep venous thrombosis (DVT) (above or below the knee). The noninferiority margin was 1%. Six secondary outcomes are reported, including death and major bleeding within 90 days. Analyses were performed by randomization group.ResultsEnrollment was stopped after an interim analysis determined the stopping rule was met, with 9711 patients (median age, 68 years; 56.8% female) of the prespecified 15 562 enrolled (62%). Of these, 9203 (95%) completed the trial. Within 90 days of surgery, symptomatic VTE occurred in 256 patients, including pulmonary embolism (79 cases), above-knee DVT (18 cases), and below-knee DVT (174 cases). The symptomatic VTE rate in the aspirin group was 3.45% and in the enoxaparin group was 1.82% (estimated difference, 1.97%; 95% CI, 0.54%-3.41%). This failed to meet the criterion for noninferiority for aspirin and was significantly superior for enoxaparin (P = .007). Of 6 secondary outcomes, none were significantly better in the enoxaparin group compared with the aspirin group.Conclusions and RelevanceAmong patients undergoing hip or knee arthroplasty for osteoarthritis, aspirin compared with enoxaparin resulted in a significantly higher rate of symptomatic VTE within 90 days, defined as below- or above-knee DVT or pulmonary embolism. These findings may be informed by a cost-effectiveness analysis.Trial RegistrationANZCTR Identifier: ACTRN12618001879257

Aims The aim of this study was to estimate the 90-day periprosthetic joint infection (PJI) rates following total knee arthroplasty (TKA) and total hip arthroplasty (THA) for osteoarthritis (OA). Methods This was a data linkage study using the New South Wales (NSW) Admitted Patient Data Collection (APDC) and the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR), which collect data from all public and private hospitals in NSW, Australia. Patients who underwent a TKA or THA for OA between 1 January 2002 and 31 December 2017 were included. The main outcome measures were 90-day incidence rates of hospital readmission for: revision arthroplasty for PJI as recorded in the AOANJRR; conservative definition of PJI, defined by T84.5, the PJI diagnosis code in the APDC; and extended definition of PJI, defined by the presence of either T84.5, or combinations of diagnosis and procedure code groups derived from recursive binary partitioning in the APDC. Results The mean 90-day revision rate for infection was 0.1% (0.1% to 0.2%) for TKA and 0.3% (0.1% to 0.5%) for THA. The mean 90-day PJI rates defined by T84.5 were 1.3% (1.1% to 1.7%) for TKA and 1.1% (0.8% to 1.3%) for THA. The mean 90-day PJI rates using the extended definition were 1.9% (1.5% to 2.2%) and 1.5% (1.3% to 1.7%) following TKA and THA, respectively. Conclusion When reporting the revision arthroplasty for infection, the AOANJRR substantially underestimates the rate of PJI at 90 days. Using combinations of infection codes and PJI-related surgical procedure codes in linked hospital administrative databases could be an alternative way to monitor PJI rates. Cite this article: Bone Joint J 2022;104-B(9):1060–1066.

Background When analyzing the outcomes of joint arthroplasty, an important factor to consider is patient comorbidities. The presence of multiple comorbidities has been associated with longer hospital stays, more postoperative complications, and increased mortality. The American Society of Anesthesiologists (ASA) physical status classification system score is a measure of a patient's overall health and has been shown to be associated with complications and mortality after joint arthroplasty. The Rx-Risk score is another measure for determining the number of different health conditions for which an individual is treated, with a possible score ranging from 0 to 47. Questions/purposes For patients undergoing THA or TKA, we asked: (1) Which metric, the Rx-Risk score or the ASA score, correlates more closely with 30- and 90-day mortality after TKA or THA? (2) Is the Rx-Risk score correlated with the ASA score? Methods This was a retrospective analysis of the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) database linked to two other national databases, the National Death Index (NDI) database and the Pharmaceutical Benefits Scheme (PBS), a dispensing database. Linkage to the NDI provided outcome information on patient death, including the fact of and date of death. Linkage to the PBS was performed to obtain records of all medicines dispensed to patients undergoing a joint replacement procedure. Patients were included if they had undergone either a THA (119,076 patients, 131,336 procedures) or TKA (182,445 patients, 215,712 procedures) with a primary diagnosis of osteoarthritis, performed between 2013 and 2017. We excluded patients with missing ASA information (THA: 3% [3055 of 119,076]; TKA: 2% [4095 of 182,445]). This left 127,761 primary THA procedures performed in 116,021 patients (53% [68,037 of 127,761] were women, mean age 68 ± 11 years) and 210,501 TKA procedures performed in 178,350 patients (56% [117,337 of 210,501] were women, mean age 68 ± 9 years) included in this study. Logistic regression models were used to determine the concordance of the ASA and Rx-Risk scores and 30-day and 90-day postoperative mortality. The Spearman correlation coefficient (r) was used to estimate the correlation between the ASA score and Rx-Risk score. All analyses were performed separately for THAs and TKAs. Results We found both the ASA and Rx-Risk scores had high concordance with 30-day mortality after THA (ASA: c-statistic 0.83 [95% CI 0.79 to 0.86]; Rx-Risk: c-statistic 0.82 [95% CI 0.79 to 0.86]) and TKA (ASA: c-statistic 0.73 [95% CI 0.69 to 0.78]; Rx-Risk: c-statistic 0.74 [95% CI 0.70 to 0.79]). Although both scores were strongly associated with death, their correlation was moderate for patients undergoing THA (r = 0.45) and weak for TKA (r = 0.38). However, the median Rx-Risk score did increase with increasing ASA score. For example, for THAs, the median Rx-Risk score was 1, 3, 5, and 7 for ASA scores 1, 2, 3, and 4, respectively. For TKAs, the median Rx-Risk score was 2, 4, 5, and 7 for ASA scores 1, 2, 3, and 4, respectively. Conclusion The ASA physical status and RxRisk were associated with 30-day and 90-day mortality; however, the scores were only weakly to moderately correlated with each other. This suggests that although both scores capture a similar level of patient illness, each score may be capturing different aspects of health. The Rx-Risk may be used as a complementary measure to the ASA score. Level of evidence Level III, therapeutic study.

Aims This study aims to describe the pre- and postoperative self-reported health and quality of life from a national cohort of patients undergoing elective total conventional hip arthroplasty (THA) and total knee arthroplasty (TKA) in Australia. For context, these data will be compared with patient-reported outcome measures (PROMs) data from other international nation-wide registries. Methods Between 2018 to 2020, and nested within a nationwide arthroplasty registry, preoperative and six-month postoperative PROMs were electronically collected from patients before and after elective THA and TKA. There were 5,228 THA and 8,299 TKA preoperative procedures as well as 3,215 THA and 4,982 TKA postoperative procedures available for analysis. Validated PROMs included the EuroQol five-dimension five-level questionnaire (EQ-5D-5L; range 0 to 100; scored worst-best health), Oxford Hip/Knee Scores (OHS/OKS; range 0 to 48; scored worst-best hip/knee function) and the 12-item Hip/Knee disability and Osteoarthritis Outcome Score (HOOS-12/KOOS-12; range 0 to 100; scored best-worst hip/knee health). Additional items included preoperative expectations, patient-perceived improvement, and postoperative satisfaction. Descriptive analyses were undertaken. Results For THA and TKA patients respectively, the patient profile was 2,850 (54.5%) and 4,684 (56.4%) female, mean age 66.8 years (SD 10.6) and 67.5 (SD 8.8), and mean BMI 29.9 kg/m2 (SD 7.7) and 32.5 kg/m2 (SD 7.0). The proportion of THA and TKA patients who reported their joint as ‘much better’ was 2,946 (92.6%) and 4,020 (81.6%) respectively, and the majority of patients were ‘satisfied’ or ‘very satisfied’ with their procedure (2,754 (86.5%) and 3,981 (80.8%)). There were 311 (9.7%) of THA patients and 516 (10.5%) of TKA patients who reported ‘dissatisfied’ or ‘very dissatisfied’ with their surgery. Conclusion Large improvements in pain, function, and overall health were evident following primary THA and TKA. Approximately 10% of patients reported dissatisfaction with their surgery. Future analyses will focus on factors contributing to dissatisfaction after arthroplasty. Cite this article: Bone Jt Open 2021;2(6):422–432.

Objective: To evaluate the psychometric properties of the 12-item Hip disability and Osteoarthritis Outcome Score (HOOS-12) and Knee injury and Osteoarthritis Outcome Score (KOOS-12) for use in evaluating outcomes after joint replacement for osteoarthritis. Design: Patient-reported outcomes data collected by the Australian Orthopaedic Association National Joint Replacement Registry were used for this analysis. HOOS-12 and KOOS-12 domain (pain, function, quality of life) and summary impact data were available. The Oxford Hip Score (OHS), Oxford Knee Score (OKS) and EQ-5D-5L were used as comparators. Instruments were administered pre-operatively and at 6 months post-operatively. Internal consistency reliability, floor and ceiling effects, convergent validity, known groups validity, and responsiveness were evaluated using standard psychometric techniques. Results: Baseline HOOS-12 and KOOS-12 data were available for 3,023 patients undergoing primary total hip replacement and 4,010 patients undergoing primary total knee replacement. At baseline, high internal consistency was demonstrated for all domains and summary scores (Cronbach's alpha: HOOS-12 = 0.81–0.93; KOOS-12 = 0.82–0.92). Post-operative ceiling effects (>15% of patients scoring the best possible score) were identified for the HOOS-12 pain (46%), function (39%) and quality of life domains (26%) and summary score (17%), and for the KOOS-12 pain (21%) and function domains (18%). The HOOS-12 and KOOS-12 could differentiate between two known groups (lowest/highest OHS or OKS quartiles post-operatively; p < 0.001) and were highly responsive to change (effect sizes for HOOS-12: 2.20–2.83; KOOS-12: 1.82–2.35). Conclusion: The HOOS-12 and KOOS-12 have good psychometric properties for capturing joint replacement outcomes including excellent responsiveness, although ceiling effects may limit monitoring of post-operative improvement Refereed/Peer-reviewed

BACKGROUND: Joint arthroplasty registries traditionally report survivorship outcomes mainly on primary joint arthroplasty. The outcome of first revision procedures is less commonly reported, because large numbers of primary procedures are required to analyze a sufficient number of first revision procedures. Additionally, adequate linkage of primary procedures to revisions and mortality is required. When undertaking revision hip surgery, it is important for surgeons to understand the outcomes of these procedures to better inform patients. QUESTIONS/PURPOSES: Using data from a large national joint registry, we asked: (1) What is the overall rate of revision of the first aseptic revision procedure for a primary THA? (2) Does the rate of revision of the first revision vary by the diagnosis for the first revision? (3) What is the mortality after the first revision, and does it vary by the reason for first revision? METHODS: The Australian Orthopaedic Association National Joint Replacement Registry longitudinally maintains data on all primary and revision joint arthroplasties, with nearly 100% capture. The analyses for this study were performed on primary THA procedures in patients with a diagnosis of osteoarthritis up to December 31, 2020, who had undergone subsequent revision. We excluded all primary THAs involving metal-on-metal and ceramic-on-metal bearing surfaces and prostheses with exchangeable necks because these designs may have particular issues associated with revisions, such as extensive soft tissue destruction, that are not seen with conventional bearings, making a comparative analysis of the first revision involving these bearing surfaces more complicated. Metal-on-metal bearing surfaces have not been used in Australia since 2017. We identified 17,046 first revision procedures from the above study population and after exclusions, included 13,713 first revision procedures in the analyses. The mean age at the first revision was 71 ± 11 years, and 55% (7496 of 13,713) of the patients were women. The median (IQR) time from the primary procedure to the first revision was 3 years (0.3 to 7.3), ranging from 0.8 years for the diagnosis of dislocation and instability to 10 years for osteolysis. There was some variation depending on the reason for the first revision. For example, patients undergoing revision for fracture were slightly older (mean age 76 ± 11 years) and patients undergoing revision for dislocation were more likely to be women (61% [2213 of 3620]). The registry has endeavored to standardize the sequence of revisions and uses a numerical approach to describe revision procedures. The first revision is the revision of a primary procedure, the second revision is the revision of the first revision, and so on. We therefore described the outcome of the first revision as the cumulative percent second revision. The outcome measure was the cumulative percent revision, which was defined using Kaplan-Meier estimates of survivorship to describe the time to the second revision. Hazard ratios from Cox proportional hazards models, adjusting for age and gender, were performed to compare the revision rates among groups. When possible, the cumulative percent second revision at the longest follow-up timepoint was determined with the available data, and when there were insufficient numbers, we used appropriate earlier time periods. RESULTS: The cumulative percent second revision at 18 years was 26% (95% confidence interval [CI] 24% to 28%). When comparing the outcome of the first revision by reason, prosthesis dislocation or instability had the highest rate of second revision compared with the other reasons for first revision. Dual‐mobility prostheses had a lower rate of second revision for dislocation or instability than head sizes 32 mm or smaller and when compared to constrained prostheses after 3 months. There was no difference between dual-mobility prostheses and head sizes larger than 32 mm. There were no differences in the rate of second revision when first revisions for loosening, periprosthetic fracture, and osteolysis were compared. If cemented femoral fixation was performed at the time of the first revision, there was a higher cumulative percent second revision for loosening than cementless fixation from 6 months to 6 years, and after this time, there was no difference. The overall mortality after a first revision of primary conventional THA was 1% at 30 days, 2% at 90 days, 5% at 1 year, and 40% at 10 years. A first revision for periprosthetic fracture had the highest mortality at all timepoints compared with other reasons for the first revision. CONCLUSION: Larger head sizes and dual-mobility cups may help reduce further revisions for dislocation, and the use of cementless stems for a first revision for loosening seems advantageous. Surgeons may counsel patients about the higher risk of death after first revision procedures, particularly if the first revision is performed for periprosthetic fracture. Level of Evidence Level III, therapeutic study.

When arthroplasty is indicated for a femoral neck fracture (FNF), it is unclear whether total hip arthroplasty (THA) or hemiarthroplasty (HA) is best. This study compares data from the Australian Orthopaedic Association National Joint Replacement Registry using contemporary surgical options.Patients from 60 to 85 years old who were treated with arthroplasty for FNF, between September 1999 and December 2019, were included if the femoral stems were cemented. Only THAs with femoral heads of ≥36 mm or dual-mobility articulations were included. Patients who had monoblock HA were excluded. Rates of revision for all aseptic failures and dislocation were compared. Competing risks of revision and death were considered using the cumulative incidence function. Subdistribution hazard ratios (HRs) for revision or death from a Fine-Gray regression model were used to compare THA and HA. Interactions of procedure with age group and sex were considered. Secondary analysis adjusting for body mass index (BMI) and American Society of Anesthesiologists (ASA) classification was also considered.There were 4,551 THA and 29,714 HA procedures included. The rate of revision for THA was lower for women from 60 to 69 years old (HR = 0.58 [95% confidence interval (CI), 0.39 to 0.85]) and from 70 to 74 years old (HR = 0.65 [95% CI, 0.43 to 0.98]) compared with HA. However, women from 80 to 85 years old (HR = 1.56 [95% CI, 1.03 to 2.35]) and men from 75 to 79 years old (HR = 1.61 [95% CI, 1.05 to 2.46]) and 80 to 85 years old (HR = 2.73 [95% CI, 1.89 to 3.95]) had an increased rate of revision when THA was undertaken compared with HA. There was no difference in the rate of revision for dislocation between THA and HA for either sex or age categories.When contemporary surgical options for FNF are used, there is a benefit with respect to revision outcomes for THA in women who are75 years old and a benefit for HA in women who are ≥80 years old and men who are ≥75 years old. There is no difference in dislocation rates.Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

Infection is a major complication following joint replacement (JR) surgery. However, little data exist regarding antibiotic utilisation following primary JR and how use changes with subsequent revision surgery. This study aimed to examine variation in antibiotic utilisation rates before and after hip replacement surgery in those revised for infection, revised for other reasons and those without revision.This retrospective cohort analysis used linked data from the Australian Orthopaedic Association National Joint Replacement Registry and Australian Government Pharmaceutical Benefits Scheme. Patients were included if undergoing total hip replacement (THR) for osteoarthritis in private hospitals between 2002 and 2017. Three groups were examined: primary THR with no subsequent revision (n = 102 577), primary THR with a subsequent revision for reasons other than periprosthetic joint infection (PJI) (n = 3156) and primary THR with a subsequent revision for PJI (n = 520). Monthly antibiotic utilisation rates and prevalence rate ratios (PRRs) with 95% confidence intervals (CIs) were calculated in the 2 years pre- and post-THR.Prior to primary THR antibiotic utilisation was 9%-10%. After primary THR, antibiotic utilisation rates were higher among patients revised for PJI (PRR 1.69, 95% CI 1.60-1.79) compared to non-revised patients, while the utilisation rate was lower in patients revised for reasons other than infection (PRR 0.96, 95% CI 0.93-0.98). For those revised for infection, antibiotic utilisation post-revision surgery was two times higher than those revised for other reasons (PRR 2.16, 95% CI 2.08-2.23). Utilisation of injectable antibiotics including, vancomycin, flucloxacillin and cephazolin was higher in those revised for PJI patients 0-2 weeks following surgery but not in those revised for other reasons compared to the non-revised group.Ongoing antibiotic utilisation after primary surgery may be an early signal of problems with the THR and should be a prompt for primary care physicians to refer patients to specialists for further appropriate investigations and management.

Background and purpose — The increase in shoulder arthroplasty may lead to a burden of revision surgery. This study compared the rate of (2nd) revision following aseptic 1st revision shoulder arthroplasty, considering the type of primary, and the class and type of the revision. Patients and methods — All aseptic 1st revisions of primary total reverse shoulder arthroplasty (rTSA group) and of primary total stemmed and stemless total shoulder arthroplasty (non-rTSA group) procedures reported to our national registry between April 2004 to December 2018 were included. The rate of 2nd revision was determined using Kaplan–Meier estimates and comparisons were made using Cox proportional hazards models. Results — There was an increased risk of 2nd revision in the 1st month only for the rTSA group (n = 700) compared with the non-rTSA group (n = 991); hazard ratio (HR) = 4.8 (95% CI 2.2–9). The cumulative percentage of 2nd revisions (CPR) was 24% in the rTSA group and 20% in the non-rTSA group at 8 years. There was an increased risk of 2nd revision for the type (cup vs. head) HR = 2.2 (CI 1.2–4.2), but not class of revision for the rTSA group. Minor (> 3 months) vs. major class revision, and humeral revision vs. all other revision types were second revision risk factors for the non-rTSA group. Interpretation — The CPR of revision shoulder arthroplasty was > 20% at 8 years and was influenced by the type of primary, the class, and the type of revision. The most common reasons for 2nd revision were instability/dislocation, loosening, and infection.

Background and purpose — A challenge comparing outcomes from total hip arthroplasty between countries is variation in preoperative characteristics, particularly comorbidity. Therefore, we investigated between-country variation in comorbidity in patients based on ASA class distribution, and determined any variation of ASA class to mortality risk between countries.\ud \ud \ud Patients and methods — All arthroplasty registries collecting ASA class and mortality data in patients with elective primary THAs performed 2012–2016 were identified. Survival analyses of the influence of ASA class on 1-year mortality were performed by individual registries, followed by meta-analysis of aggregated data.\ud \ud \ud Results — 6 national registries and 1 US healthcare organization registry with 418,916 THAs were included. There was substantial variation in the proportion of ASA class III/IV, ranging from 14% in the Netherlands to 39% in Finland. Overall, 1-year mortality was 0.93% (95% CI 0.87–1.01) and increased from 0.2% in ASA class I to 8.9% in class IV. The association between ASA class and mortality measured by hazard ratios (HR) was strong in all registries even after adjustment for age and sex, which reduced them by half in all registries. Combined adjusted HRs were 2.0, 6.1, and 22 for ASA class II–IV vs. I, respectively. Associations were moderately heterogeneous across registries.\ud \ud \ud Interpretation — We observed large variation in ASA class distribution between registries, possibly explained by differences in background morbidity and/or international variation in access to surgery. The similar, strong mortality trends by ASA class between countries enhance the relevance of its use as an indicator of comorbidity in international registry studies.

Aims This study aimed to describe the use of revision knee arthroplasty in Australia and examine changes in lifetime risk over a decade. Methods De-identified individual-level data on all revision knee arthroplasties performed in Australia from 2007 to 2017 were obtained from the Australian Orthopaedic Association National Joint Replacement Registry. Population data and life tables were obtained from the Australian Bureau of Statistics. The lifetime risk of revision surgery was calculated for each year using a standardized formula. Separate calculations were undertaken for males and females. Results In total, 43,188 revision knee arthroplasty procedures were performed in Australia during the study period, with a median age at surgery of 69 years (interquartile range (IQR) 62 to 76). In 2017, revision knee arthroplasty rates were highest for males aged 70 to 79 years (102.9 procedures per 100,000 population). Lifetime risk of revision knee arthroplasty for females increased slightly from 1.61% (95% confidence interval (CI) 1.53% to 1.69%) in 2007 to 2.22% (95% CI 2.13% to 2.31%) in 2017. A similar pattern was evident for males, with a lifetime risk of 1.43% (95% CI 1.36% to 1.51%) in 2007 and 2.02% (95% CI 1.93% to 2.11%) in 2017. A decline in procedures performed for loosening/lysis (from 41% in 2007 to 24% in 2017) and pain (from 14% to 9%) was evident, while infection became an increasingly common indication (from 19% in 2007 to 29% in 2017). Conclusion Well-validated national registry data can help us understand the epidemiology of revision knee arthroplasty, including changing clinical indications. Despite a small increase over a decade, the lifetime risk of revision knee arthroplasty in Australia is low at one in 45 females and one in 50 males. These methods offer a population-level approach to quantifying revision burden that can be used for ongoing national surveillance and between-country comparisons. Cite this article: Bone Joint J 2022;104-B(5):613–619.

Obesity is associated with the development of knee osteoarthritis (OA). The aim of this study was to examine the incidence of obesity in patients undergoing knee replacement (KR) for OA in Australia compared to the incidence of obesity in the general population.A cohort study was conducted, comparing data from the Australian Bureau of Statistics (ABS) 2017-2018 National Health Survey with data from the National Joint Replacement Registry. The distribution of patients who underwent KR from July 2017 to June 2018 by BMI category was compared to the distribution of the general population, in age and gender sub-groups.During the study period, 35.6% of Australian adults were overweight and 31.3% were obese. Of the 56 217 patients who underwent primary KR for OA, 31.9% were overweight and 57.7% were obese. The relative risk of undergoing KR for OA increased with increasing BMI category. Class 1, 2 and 3 obese females aged 55-64 years were 4.7, 8.4 and 17.3 times more likely to undergo KR than their normal weight counterparts, respectively. Males in the same age and BMI categories were 3.4, 4.5 and 5.8 times more likely to undergo KR, respectively. Class 3 obese patients underwent KR 7 years younger, on average, than normal weight individuals.Obesity is associated with an increased risk of undergoing KR, and at a younger age, particularly for females. There is an urgent need for a societal level approach to address the prevalence of obesity, to reduce the burden of obesity related KR.

Background and purpose — Rates of knee replacement (KR) are increasing worldwide. Based on population and practice changes, there are forecasts of a further exponential increase in primary knee replacement through to 2030, and a corresponding increase in revision knee replacement. We used registry data to document changes in KR over the past 15 years, comparing practice changes across Sweden, Australia, and the United States. This may improve accuracy of future predictions. Patients and methods — Aggregated data from the Swedish Knee Arthroplasty Register (SKAR), the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR), and the Kaiser Permanente Joint Replacement Registry (KPJRR) were used to compare surgical volume of primary and revision KR from 2003 to 2017. Incidence was calculated using population census statistics from Statistics Sweden and the Australian Bureau of Statistics, as well as the yearly active membership numbers from Kaiser Permanente. Further analysis of KR by age < 65 and ≥ 65 years was carried out. Results — All registries recorded an increase in primary and revision KR, with a greater increase seen in the KPJRR. The rate of increase slowed during the study period. In Sweden and Australia, there was a smaller increase in revision surgery compared with primary procedures. There was consistency in the mean age at surgery, with a steady small decrease in the proportion of women having primary KR. The incidence of KR in the younger age group remained low in all 3 registries, but the proportional increases were greater than those seen in the ≥ 65 years of age group. Interpretation — There has been a generalized deceleration in the rate of increase of primary and revision KR. While there are regional differences in KR incidence, and rates of change, the rate of increase does not seem to be as great as previously predicted.

ObjectivesObesity is a well-recognised risk factor for osteoarthritis (OA). Our aim is to characterise body mass index (BMI)-associated pathological changes in the osteochondral unit and determine if obesity is the major causal antecedent of early joint replacement in patients with OA.MethodsWe analysed the correlation between BMI and the age at which patients undergo total knee replacement (TKR) in 41 023 patients from the Australian Orthopaedic Association National Joint Replacement Registry. We then investigated the effect of BMI on pathological changes of the tibia plateau of knee joint in a representative subset of the registry.Results57.58% of patients in Australia who had TKR were obese. Patients with overweight, obese class I & II or obese class III received a TKR 1.89, 4.48 and 8.08 years earlier than patients with normal weight, respectively. Microscopic examination revealed that horizontal fissuring at the osteochondral interface was the major pathological feature of obesity-related OA. The frequency of horizontal fissure was strongly associated with increased BMI in the predominant compartment. An increase in one unit of BMI (1 kg/m2) increased the odds of horizontal fissures by 14.7%. 84.4% of the horizontal fissures were attributable to obesity. Reduced cartilage degradation and alteration of subchondral bone microstructure were also associated with increased BMI.ConclusionsThe key pathological feature in OA patients with obesity is horizontal fissuring at the osteochondral unit interface. Obesity is strongly associated with a younger age of first TKR, which may be a result of horizontal fissures.

Background: To provide an estimate of the population at risk for late complications of arthroplasty, we aimed to determine the prevalence of Australians living with one or more joint replacements. Methods: Data included all arthroplasty procedures performed in Australia from 2003 to 2016 recorded by the Australian Orthopaedic Association National Joint Replacement Registry. The age- and gender-specific Australian population was obtained from the Australian Bureau of Statistics and used as denominator data. Survival data for each joint replacement, and of individuals, were used to estimate the arthroplasty prevalence. Analyses by age, gender and joint replacement site were undertaken. Prevalence estimates were augmented with procedural data captured before 2003 modelled with assumptions accounting for age and gender distributions, overall survival and arthroplasty revision rates. Results: By the end of 2016, there were 824 769 Australians living with at least one joint replacement, representing 3.4% of the total population. The prevalence of joint replacement is increasing in all age groups, but was highest amongst older Australians, with an overall prevalence of 22.5%, and 13.3% in those aged >85 years and 65–84 years, respectively. The prevalence of people living with multiple joint replacements is increasing more rapidly than patients who have undergone only one joint replacement procedure. Conclusion: The prevalence of older Australians living with joint replacements is rapidly increasing, providing an estimate of the population-at-risk for late complications of arthroplasty including peri-prosthetic infection and fracture. Refereed/Peer-reviewed

To identify subgroups of community-dwelling older adults and to assess their longitudinal associations with long-term osteoarthritis (OA) outcomes. 1046 older adults aged 50–80 years were studied. At baseline, body mass index (BMI), pedometer-measured ambulatory activity (AA), and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) determined knee pain and information on comorbidities were obtained. Tibial cartilage volume and bone-marrow lesions (BMLs) were assessed using MRI at baseline and 10 years and total knee replacements (TKR) by data linkage to the Australian Orthopaedic Association National Joint Replacement Registry. Latent class analysis was used to determine participant subgroups, considering baseline BMI, AA, pain and comorbidities, and linear mixed-effects or log-binomial models were used to assess the associations. Three subgroups/classes were identified: subgroup 1 (43%): Normal/overweight participants with higher AA, lower pain and lower comorbidities; subgroup 2 (32%): Overweight participants with lower AA, mild pain and higher comorbidities; subgroup 3 (25%): Obese participants with lower AA, mild pain and higher comorbidities. Subgroup 3 had greater cartilage volume loss (β − 60.56 mm3, 95% CI − 105.91, − 15.21) and a higher risk of TKR (RR 3.19, 95% CI 1.75, 5.81), compared to subgroup 1. Subgroup 2 was not associated with cartilage volume change (β 13.06 mm3, 95% CI − 30.87, 57.00) or risk of TKR (RR 1.16, 95% CI 0.56, 2.36), compared to subgroup 1. Subgroup membership was not associated with worsening BMLs. Our findings suggest the existence of homogeneous subgroups of participants and support the utility of identifying patterns of characteristics/risk factors that may cluster together and using them to identify subgroups of people who may be at a higher risk of developing and/or progressing OA.

Background: Total hip replacement (THR) and total knee replacement (TKR) are cost-effective interventions to reduce pain and disability associated with osteoarthritis, however there is no clear guidelines available to determine appropriate patient selection and the timing of surgery. This prospective cohort study aimed to evaluate the hospital- and surgeon-level variation in the severity of patient-reported symptoms prior to THR and TKR. Methods: Patients undergoing primary THR (n = 4330) or TKR (n = 7054) for osteoarthritis who participated in a national registry-led Patient Reported Outcome Measures (PROMs) pilot program were included in the analysis. Pre-operative Oxford Hip Score (OHS) and Oxford Knee Score (OKS) (range 0–48; representing worst to best hip/knee pain and function) data were examined for variation between private and public hospitals and between surgeons using linear mixed models. Results: Pre-operative mean OHS was significantly higher (better) in patients whose surgery was performed in a private hospital compared to public hospitals; 21.39 versus 18.11 (mean difference 3.27, 95% CI 1.75, 4.79). For OKS, the difference between private hospital and public hospital scores was dependent on BMI and gender. Most of the variation in pre-operative OHS and OKS was not at the individual hospital- or surgeon-level, which explained only a negligible proportion of the model variance (⟨5%) for THR and TKR. Conclusion: Apart from a difference between private and public hospitals, there was little between-hospital or between-surgeon symptom variation in joint-specific pain and function prior to THR or TKR. The findings suggest consistency in the surgical thresholds for patients being offered hip and knee joint replacement procedures. Refereed/Peer-reviewed

BACKGROUND Compared with other total hip arthroplasty (THA) approaches, the anterior approach has an increased rate of revision for femoral-sided complications, and certain stems may increase this risk. The present study aimed to assess the outcome of THA by surgical approach, according to the femoral stem utilized in the procedure. METHODS Data from the Australian Orthopaedic Association National Joint Replacement Registry were analyzed for patients undergoing primary THA for osteoarthritis via the anterior or posterior approach with use of 1 of 5 of the most common cementless femoral stems from January 2015 to December 2019. The primary outcome measures were the cumulative percent revision (CPR) for all causes and for femoral stem loosening and fracture. The CPR was compared between THAs performed via the anterior and posterior approaches for all stems and for each individual femoral stem, as well as between individual femoral stems for each approach. RESULTS The study included 48,716 THAs performed with use of cementless stems, of which 22,840 utilized an anterior approach and 25,876 utilized a posterior approach. There was no difference in the all-cause CPR between the anterior and the posterior approach, but the anterior approach had a higher CPR for loosening (hazard ratio [HR], 2.00; 95% confidence interval [CI], 1.48 to 2.69; p < 0.001) and fracture (HR, 1.78; 95% CI, 1.34 to 2.35; p < 0.001). There was apparent variation in the CPR across the different cementless stems when an anterior approach was utilized. The Quadra-H (Medacta) had a higher all-cause CPR when compared with the Polarstem (Smith & Nephew; HR, 1.49; 95% CI, 1.16 to 1.91; p = 0.002) and Corail (DePuy Synthes; HR, 1.31; 95% CI, 1.00 to 1.70; p = 0.0478). Variation was less apparent with the posterior approach. CONCLUSIONS THAs performed via the anterior approach had higher rates of revision for femoral stem loosening and fracture, with greater variation in outcomes between individual stems. LEVEL OF EVIDENCE Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.