Waiting times for arthroplasty surgery in Northern Ireland are among the longest in the National Health Service, which have been further lengthened by the onset of the SARS-CoV-19 global pandemic in March 2020. The Department of Health (DoH) in Northern Ireland has announced a new Elective Care Framework (ECF), with the framework proposing that by March 2026 no patient will wait more than 52 weeks for inpatient/day case treatment. We aimed to assess the feasibility of achieving this with reference to Total Hip Arthroplasty (THA). Waiting list information was obtained via a Freedom of Information request to the DoH (May 2021) and National Joint Registry data was used to determine baseline operative numbers. Mathematical modelling was undertaken to calculate the time taken to meet the ECF target and also to determine the time to clear the waiting lists for THA using the number of patients currently on the waiting list and percentage operating capacity relative to pre-Covid-19 capacity to determine future projections. As of May 2021, there were 3,757 patients awaiting primary THA in Northern Ireland. Prior to April 2020, there were a mean 2,346 patients/annum added to the waiting list for primary THA and there were a mean 1,624 primary THAs performed per annum. The ECF targets for THA will only be achieved in 2026 if operating capacity is 200% of pre COVID-19 pandemic capacity and will be achieved in 2030 if capacity is 170%. Surgical capacity must exceed pre-Covid capacity by at least 30% to meet ongoing demand. THA capacity was significantly reduced following resumption of elective orthopaedics post-COVID-19 (22% of pre-COVID-19 capacity – 355 THAs/annum post-COVID-19 versus 1,624/annum pre-COVID-19). This modelling demonstrates that, in the absence of major funding and reorganisation of elective orthopaedic care, the targets set out in the ECF will not be achieved with regards to hip arthroplasty. Waiting times for THA surgery in the NHS in Northern Ireland are likely to remain greater than 52 weeks for most of this decade

Aims. This study describes the variation in the annual volumes of revision hip arthroplasty (RHA) undertaken by consultant surgeons nationally, and the rate of accrual of RHA and corresponding primary hip arthroplasty (PHA) volume for new consultants entering practice. Methods. National Joint Registry (NJR) data for England, Wales, Northern Ireland, and the Isle of Man were received for 84,816 RHAs and 818,979 PHAs recorded between April 2011 and December 2019. RHA data comprised all revision procedures, including first-time revisions of PHA and any subsequent re-revisions recorded in public and private healthcare organizations. Annual procedure volumes undertaken by the responsible consultant surgeon in the 12 months prior to every index procedure were determined. We identified a cohort of ‘new’ HA consultants who commenced practice from 2012 and describe their rate of accrual of PHA and RHA experience. Results. The median annual consultant RHA volume, averaged across all cases, was 21 (interquartile range (IQR) 11 to 34; range 0 to 181). Of 1,695 consultants submitting RHA cases within the study period, the top 20% of surgeons by annual volume performed 74.2% of total RHA case volume. More than half of all consultants who had ever undertaken a RHA maintained an annual volume of just one or fewer RHA, however, collectively contributed less than 3% of the total RHA case volume. Consultant PHA and RHA volumes were positively correlated. Lower-volume surgeons were more likely to undertake RHA for urgent indications (such as infection) as a proportion of their practice, and to do so on weekends and public holidays. Conclusion. The majority of RHAs were undertaken by higher-volume surgeons. There was considerable variation in RHA volumes by indication, day of the week, and between consultants nationally. The rate of accrual of RHA experience by new consultants is low, and has important implications for establishing an experienced RHA consultant workforce. Cite this article: Bone Joint J 2023;105-B(10):1060–1069

Total hip replacement (THR) for end-stage osteoarthritis is a commonly performed cost-effective procedure, which provides patients with significant clinical improvement. Estimating the future demand for joint replacement is important to identify the healthcare resources needed. We estimated the number of primary THRs that will need to be performed up to the year 2060. We used data from The National Joint Registry for England, Wales, Northern Ireland and the Isle of Man on the current volume of primary THR (n=94,936) performed in 2018. We projected future numbers of THR using a static estimated rate from 2018 applied to population growth forecast data from the UK Office for National Statistics up to 2060. By 2060, primary THR volume would increase from 2018 levels by an estimated 37.7% (n=130,766). For both males and females demand for surgery was also higher for patients aged 70 and over, with older patients having the biggest relative increase in volume over time: 70–79 years (144.6% males, 141.2% females); 80–89 years (212.4% males, 185.6% females); 90 years and older (448.0% males, 298.2% females). By 2060 demand for THR is estimated to increase by almost 40%. Demand will be greatest in older patients (70 years+), which will have significant implications for the health service that requires forward planning given morbidity and resource use is higher in this population. There is a backlog of current demand with cancellation of elective surgery due to seasonal flu pressures in 2017 and now Covid-19 in 2020. Orthopaedics already has the largest waiting list of any speciality. These issues will negatively impact the health services ability to deliver timely joint replacement to many patients for a number of years and require urgent planning

Total hip replacements (THRs) are performed by surgeons at various stages in their training, with varying levels of senior supervision. There is a balance between protecting training opportunities for the next generation of surgeons, while limiting the exposure of patients to unnecessary risk during the training process. The aim of this study was to examine the association between surgeon grade, the senior supervision of trainees, and the risk of revision following THR. We included 603 474 primary THRs recorded in the National Joint Registry for England, Wales, Northern Ireland, and the Isle of Man (NJR) between 2003 and 2016 for an indication of osteoarthritis. Exposures were the grade of the surgeon (consultant or trainee), and whether trainees were supervised by a scrubbed consultant or not. Outcomes were all-cause revision, the indication for revision, and the temporal variation in risk of revision (all up to 10 years). Net failure was calculated using Kaplan-Meier analysis and adjusted analyses used Cox regression and flexible parametric survival analysis (adjusted for patient, operative, and unit level factors). There was no association between surgeon grade and all-cause revision up to 10 years (crude hazard ratio (HR) 0·999, 95% confidence interval (CI) 0.936–1.065; p=0.966); a finding which persisted with adjusted analysis. Adjusted analysis demonstrated an association between trainees operating without supervision by a scrubbed consultant and an increase in all-cause revision (HR 1.100, 95% CI 1.002–1.207; p=0.045). There was an association between the trainee-performed THRs and revision due to instability (crude HR 1.143, 95% CI, 1.007–1.298; p=0.039). However, this was not observed in fully adjusted models, or when trainees were supervised by a scrubbed consultant. Within the current training system in the United Kingdom, trainees achieve comparable outcomes to consultant surgeons when supervised by a scrubbed consultant. Revision rates are higher when trainees are not supervised by a scrubbed consultant but remain within internationally recognised acceptable limits

Introduction. Analysis of registry data shows that few units achieve results better than 99·98% control limits. Implant selection is considered a predictor of outcome variation in joint replacement. We analysed the outcomes of a unit with statistically “better than expected” results and compared to all other units within the National Joint Registry for England, Wales, Northern Ireland and Isle of Man (NJR). We sought to determine whether improved implant survival following primary total hip replacement (THR) is a centre effect or mediated by implant selection. Methods. We identified 664,761 THRs in the NJR. The exposure was the unit in which the THR was implanted and the outcome all-cause revision. Net failure was estimated using Kaplan-Meier and adjusted analyses used flexible parametric survival analysis. Results. The crude 10-year revision rate for THRs was 1·7% (95% CI: 1·3, 2·3) in the exemplar centre and 2·9% (95% CI: 2·8, 3·0) elsewhere (log rank test P<0·001). Of 6,230 THRs performed in the exemplar centre, 99·9% used the same femoral stem. After restricting analyses to this stem, crude survival from other units was 2·3% (95% CI: 2·2, 2·4) (log-rank test p=0·05). Age and sex adjusted analyses, restricted to the same stem/cup combinations as the exemplar centre, show no demonstrable difference in restricted mean survival time between groups (p=0·28). Conclusion. These results suggest the “better than expected” performance of an exemplar centre can be replicated by adopting key treatment decisions, such as implant selection. These decisions are easier to replicate than technical skills or system factors. This is an important and easily applicable lesson for all branches of medicine highlighting the potential pre-eminence of decision making over technical expertise

Introduction. Total hip arthroplasty (THA) is indicated in independently mobile patients sustaining displaced intracapsular hip fractures. Studies presently suggest that the anterolateral approach is preferable to the posterior approach due to a perceived reduced risk of reoperations and dislocations. However, these observations come from small studies with short follow-up. We assessed whether surgical approach in THA performed for hip fractures effects outcomes. Patients and Methods. A retrospective observational study was performed using data collected prospectively by the National Joint Registry for England, Wales, Northern Ireland and the Isle of Man. All primary stemmed THAs implanted for hip fractures between 2003–2015 were eligible for inclusion (n=19,432). The two surgical approach groups (posterior versus anterolateral) were propensity-score matched for multiple potential patient and surgical confounding factors (n=14,536, with 7,268/group). Outcomes (implant survival, patient survival, intraoperative complications) were compared between the approach groups using regression analysis. Results. Five-year implant survival rates were similar between posterior and anterolateral approaches (97.3% vs. 97.4%; sub-hazard ratio (SHR)=1.15 (95% CI 0.93–1.42)). Five-year implant survival rates free from revision for dislocation (SHR=1.28 (CI=0.89–1.84)) and free from revision for periprosthetic fracture (SHR=1.03 (CI=0.68–1.56)) were also comparable. Thirty-day patient survival was significantly higher with a posterior approach (99.5% vs. 98.8%; hazard ratio (HR)=0.44 (CI=0.30–0.64)), which persisted at 1-year (HR=0.73 (CI=0.64–0.84)) and 5-years (HR=0.87 (CI=0.81–0.94)). The posterior approach had a lower risk of intraoperative complications (odds ratio=0.59 (CI=0.45–0.78)). Discussion. This is the largest study assessing the influence of surgical approach on outcomes following THA performed for hip fractures. In THA for hip fractures, the posterior approach had a similar risk of revision, and a lower risk of mortality and intraoperative complications compared with the anterolateral approach. Conclusion. We propose that the posterior approach is safer than the anterolateral approach when performing THA for hip fractures and should be preferred where possible

Outcomes following metal-on-metal hip replacement (MoMHR) revision surgery for adverse reactions to metal debris (ARMD) have been poor, and inferior compared with non-ARMD revisions. Subsequently, surgeons and worldwide authorities widely recommended early revision for ARMD, with a lower surgical threshold adopted. However, the impact of early surgery for ARMD is unknown. We compared the rates of adverse outcomes following MoMHR revision surgery in matched ARMD and non-ARMD patients. We performed a retrospective observational study using data from the National Joint Registry for England, Wales, Northern Ireland and the Isle of Man. All MoMHR patients subsequently undergoing revision surgery for any indication between August 2008 and August 2014 were eligible. ARMD and non-ARMD revisions were matched one-to-one for multiple potential confounding factors using propensity scores. Adverse outcomes following revision surgery (intra-operative complications, mortality, re-revision surgery) were compared between matched groups using regression analysis. In 2,576 matched MoMHR revisions (ARMD=1,288 and non-ARMD=1,288), intra-operative complications were similar between ARMD (2.4%) and non-ARMD (2.5%) revisions (odds ratio=0.97, 95% CI=0.59–1.60; p=0.899). All-cause mortality rates were lower following ARMD revision compared with non-ARMD revision (hazard ratio (HR)=0.43, 95% CI=0.22–0.86; p=0.018). All-cause re-revision rates were lower following ARMD revision compared with non-ARMD revision (HR=0.52, 95% CI=0.36–0.75; p<0.001). Compared with ARMD revision (5-years=94.3%), MoMHR revisions for infection (5-years=81.2%) and dislocation/subluxation (5-years=81.9%) had the lowest implant survival rates. Contrary to previous observations, MoMHRs revised for ARMD have approximately half the risk of re-revision and death compared to non-ARMD revisions. We suspect worldwide regulatory authorities have positively influenced outcomes following ARMD revision by widely recommending that surgeons exercise a lower revision threshold. Our findings suggest the threshold for ARMD revision surgery need not be lowered further. The high risk of failure following MoMHR revision for infection and dislocation is concerning

Background. Antibiotic loaded bone cement (ALBC) is commonly used in cemented total hip arthroplasty (THA) in an attempt to reduce the risk of prosthetic joint infection (PJI). However, its role versus plain cement remains controversial due to the potential risk of developing resistant organisms and potential excess costs incurred from its usage. We investigated the relationship of ALBC and plain cement in affecting outcome of revision surgery after primary THA. Methodology. We conducted a retrospective study of data collected from National Joint Registry for England and Wales, Northern Ireland and the Isle of Man between 1. st. September 2005 until 31. st. August 2017. A logistic regression analysis model was used to investigate the association between ALBC versus plain cement and the odds ratio (OR) for revision, adjusting for age, ASA grade, bearing surfaces, head size and cup and stem fixation. Indications for revision recorded in NJR were considered in separate models. Results. We identified 418,925 THAs where bone cements were used (22,037 plain cement; 396,888 ALBC). After adjusting for confounding factors, the risk of revision for infection was lower with ALBC (OR 0.77, 95% CI 0.62–0.95). There was also lower risk of revision for aseptic loosening of stem (OR 0.53, 95% CI 0.39–0.72), aseptic loosening of socket (OR 0.46, 95% CI 0.37– 0.58). When breaking down hips into fully cemented or hybrid fixation, the protective effect of ALBC against infection was only apparent in fully cemented (OR 0.65, 95% CI 0.48–0.87) when compared against hybrid fixation (OR 0.90, 95% CI 0.66–1.23). Discussion. Within the limits of registry analysis, this study has demonstrated an association between the use of ALBC and lower rates of revision for infection and aseptic loosening. Conclusion. This finding supports the current use of ABLC in cemented THAs

Recent studies have reported on non-metal-on-metal hip arthroplasty (non-MoMHA) patients requiring revision surgery for adverse reactions to metal debris (ARMD). Although the outcomes following revision surgery for ARMD in MoMHA patients are known to generally be poor, little evidence exists regarding outcomes following non-MoMHA revision surgery performed for ARMD. We determined the outcomes following non-MoMHA revision surgery performed for ARMD, and identified predictors of re-revision. We performed a retrospective observational study using data from the National Joint Registry for England, Wales, Northern Ireland and the Isle of Man. All primary non-MoMHA patients who subsequently underwent revision surgery for ARMD between 2008–2014 were included (n=185). Outcome measures following ARMD revision were intraoperative complications, mortality, and re-revision surgery. Predictors of re-revision surgery were identified using Cox regression analysis. Intra-operative complications occurred in 6.0% (n=11) of ARMD revisions. The cumulative 4-year patient survival rate was 98.2% (95% CI=92.9–99.5%). Re-revision surgery was performed in 13.5% (n=25) of hips at a mean time of 1.2 years (range 0.1–3.1 years) following ARMD revision. Infection (32%), dislocation/subluxation (24%), and aseptic loosening (24%) were the commonest re-revision indications. The cumulative 4-year implant survival rate was 83.8% (95% CI=76.7%-88.9%). Significant predictors of re-revision were: multiple revision indications (Hazard Ratio (HR)=2.78; 95% CI=1.03–7.49; p=0.043), incomplete revision procedures (including modular component exchange only) (HR=5.76; 95% CI=1.28–25.9; p=0.022), and ceramic-on-polyethylene revision bearings (HR=3.08; 95% CI=1.01–9.36; p=0.047). Non-MoMHA patients undergoing ARMD revision have a high short-term risk of re-revision. Infection, dislocation/subluxation, and aseptic loosening were the commonest re-revision indications. Furthermore, important and potentially modifiable predictors of future re-revision were identified. Although the poor prognostic factors identified require validation in future studies, our findings may be used to counsel patients about the risks associated with ARMD revision surgery, and guide decisions about the reconstructive procedure

Total hip replacements (THRs) provide pain relief and improved function to thousands of patients suffering from end-stage osteoarthritis, every year. Over 800 different THR constructs were implanted in the UK in 2017. To ensure reliable implants are used, a NICE revision benchmark of 5% after 10 years exists. Given the 10-year cumulative mortality of patients under 55 years of age receiving THRs is only 5% and that a recent study suggests 25-year THR survival of 58%, we aim to produce revision estimates out to 30 years that may guide future long-term benchmarks.

The local database of the Princess Elizabeth Orthopaedic Centre (PEOC), Exeter, holds data on over 20,000 patients with nearly 30-years follow-up with contemporary prostheses. A previous study suggests that the results of this centre are generalisable if comparisons restricted to the same prostheses. Via flexible parametric survival analysis, we created an algorithm using this database, for revision of any part of the construct for any reason, controlling for age and gender. This algorithm was applied to 664,761 patients in the NJR who have undergone THR, producing a revision prediction for patients with the same prostheses as those used at this centre.

Using our algorithm, the 10-year predicted revision rate of THRs in the NJR was 2.2% (95% CI 1.8, 2.7) based on a 68-year-old female patient; well below the current NICE benchmark. Our predictions were validated by comparison to the maximum observed survival in the NJR (14.2 years) using restricted mean survival time (P=0.32). Our predicted cumulative revision estimate after 30 years is 6.5% (95% CI 4.5, 9.4). The low observed and predicted revision rate with the prosthesis combinations studied, suggest current benchmarks may be lowered and new ones introduced at 15 and 20 years to encourage the use of prostheses with high survival.

Background

Total hip replacement (THR) is clinically and cost-effective. The surgical approach influences outcomes, however there is little generalisable and robust evidence to guide practice. We assessed the effect of surgical approach on THR outcomes.

Arthroplasty registries are important for the surveillance of joint replacements and the evaluation of outcome. Independent validation of registry data ensures high quality. The ability for orthopaedic implant retrieval centres to validate registry data is not known. We analysed data from the National Joint Registry for England, Wales and Northern Ireland (NJR) for primary metal-on-metal hip arthroplasties performed between 2003 and 2013. Records were linked to the London Implant Retrieval Centre (RC) for validation. A total of 67 045 procedures on the NJR and 782 revised pairs of components from the RC were included. We were able to link 476 procedures (60.9%) recorded with the RC to the NJR successfully. However, 306 procedures (39.1%) could not be linked. The outcome recorded by the NJR (as either revised, unrevised or death) for a primary procedure was incorrect in 79 linked cases (16.6%). The rate of registry-retrieval linkage and correct assignment of outcome code improved over time. The rates of error for component reference numbers on the NJR were as follows: femoral head category number 14/229 (5.0%); femoral head batch number 13/232 (5.3%); acetabular component category number 2/293 (0.7%) and acetabular component batch number 24/347 (6.5%).

Registry-retrieval linkage provided a novel means for the validation of data, particularly for component fields. This study suggests that NJR reports may underestimate rates of revision for many types of metal-on-metal hip replacement. This is topical given the increasing scope for NJR data. We recommend a system for continuous independent evaluation of the quality and validity of NJR data.

Cite this article: Bone Joint J 2015;97-B:10–18.

Over 800 total hip replacement (THR) constructs were implanted in the UK in 2017. To ensure reliable implants are used, a NICE revision benchmark of 5% after 10 years exists. Surgeons are guided in choice by organisations such as the Orthopaedic Data Evaluation Panel (ODEP). Currently, ODEP publishes ratings for stem and cup separately and not for constructs. We used NJR data to investigate whether revision estimates of an individual stem (with all cups) is an accurate indicator of survival of all constructs using that stem.

The dataset comprised 234,289 THRs using the most frequently implanted stem between 2004 and 2017. Crude ten-year revision estimates were calculated using Kaplan-Meier for all THRs and for the five most implanted constructs. Adjusted comparisons between individual constructs and the overall stem revision estimate were made using flexible parametric survival analysis.

The 10-year crude, revision estimate for all THRs was 2.3% (95% CI 2.2, 2.4). Only four of the most frequently used constructs had long enough follow-up to analyse. 10-year estimates for these constructs ranged from 1.8% (95% CI 1.5, 2.1) to 3.7% (95% CI 3.2, 4.1), a log-rank test revealed strong evidence against the null hypothesis that revision estimates were the same for all constructs (p<0.001). Adjusted for age, sex and ASA, three of the four constructs showed a difference in 10-year revision estimates compared to this stem with all cups (P=0.03, P<0.001, P<0.001).

This study suggests 10-year revision estimates for all THRs using the most implanted stem in the NJR are not representative of all constructs involving that stem in crude or adjusted analyses. Current benchmarking systems report survival for the stem in combination with all cups and not for constructs. We suggest that benchmarking ratings basing on revision estimates for THR constructs would provide more accurate information, enabling informed construct decisions.

Background

Few studies have compared aspirin with DOACs (direct oral anticoagulants = direct thrombin inhibitors and factor Xa inhibitors) for venous thromboembolism (VTE) prophylaxis following total hip and knee replacement (THR and TKR). We assessed the efficacy and safety of aspirin compared with DOACs for VTE prophylaxis following THR and TKR using the world's largest joint replacement registry.

Our previous work presented at BHS revealed a reduced risk of revision for all reasons in THAs using lipped (asymmetric) liners. Some audience members felt that this finding may be due to unaccounted confounders and the hip surgery community remains sceptical.

A fully adjusted Cox model was built after exploratory Kaplan-Meier analyses. The following surgical approaches were included in the analysis: Posterior, Hardinge/anterolateral, Other. The variables included in the final Cox model included: Gender, liner asymmetry, age, head composition, stem fixation method, head diameter, indication for implantation and surgical approach. An additional analysis of the 3 most commonly used polyethylene liners with both a flat and asymmetric version was performed.

In the fully adjusted Cox model, the use of a flat liner was associated with increased risk of revision for instability (HR: 1.79, 95%CI: 1.52–2.10) and increased risk of revision for all reasons (HR 1.195, 95%CI: 1.104 – 1.293) when compared to THAs utilising flat liners. This finding was upheld in the product specific analysis.

When utilising flat liners, the Hardinge/anterolateral approach was associated with a reduced risk of revision for instability compared to the posterior approach (HR 0.56, 95%CI: 0.446 to 0.706). When an asymmetric liner was used, there was no significant difference in the risk of revision for instability between the Hardinge/anterolateral approach and the posterior approach (HR 0.838, 95%CI: 0.633 – 1.110).

The use of polyethylene-based bearings gives the surgeon the option to use asymmetric liners. The reduced risk of revision in THAs with asymmetric liners was seen in the analysis of the complete dataset and in the product specific analysis. Our results demonstrate that the posterior approach, when used with asymmetric XLPE liners, is not associated with a higher risk of revision for instability as historical data suggested.

Aim

To assess the effect of the bearing surface and head size on the survival of total hip replacements with modern bearing surface combinations.

Computer aided Total Hip Arthroplasty (THA) surgery is known to improve implantation precision, but clinical trials have failed to demonstrate an improvement in survivorship or patient reported outcome measures (PROMs). Our aim was to compare the risk of revision, PROMs and satisfaction rates between computer guided and THA implanted without computer guidance.

We used the National Joint Registry dataset and linked PROMs data. Our sample included THAs implanted for osteoarthritis using cementless acetabular components from a single manufacturer (cementless and hybrid). An additional analysis was performed limiting the sample size to THAs using cementless stems (fully cementless). The primary endpoint was revision (of any component) for any reason. Kaplan Meier survivorship analysis and an adjusted Cox Proportional Hazards model were used.

41683 non computer guided, and 871 (2%) computer guided cases were included in our cementless and hybrid analysis. 943 revisions were recorded in the non-guided and 7 in the computer guided group (adjusted Log-rank test, p= 0.028). Cumulative revision rate at 10 years was 3.88% (95%CI: 3.59 – 4.18) and 1.06% (95%CI: 0.45 – 2.76) respectively. Cox Proportional Hazards adjusted HR: 0.45 (95%CI: 0.21 – 0.96, p=0.038). In the fully cementless group, cumulative revision rate at 10 years was 3.99% (95%CI: 3.62 – 4.38) and 1.20% (95%CI: 0.52 – 3.12) respectively. Cox Proportional Hazards adjusted HR: 0.47 (95%CI: 0.22 – 1.01, p=0.053). There was no statistically significant difference in the 6-month Oxford Hip Score, EQ-5D, EQ-VAS and success rates. Patient Satisfaction (single-item satisfaction outcome measure) was improved in the computer guided group but this finding was limited by a reduced number of responses.

In this single manufacturer acetabular component analysis, the use of computer guided surgery was associated with a significant reduction in the early risk of revision. Causality cannot be inferred in view of the observational nature of the study, and further database and prospective studies are recommended to validate these findings.

Aim

To assess the effect of different polyethylene modifications on Total Hip Replacement survival.

Aims. To develop and externally validate a parsimonious statistical prediction model of 90-day mortality after elective total hip arthroplasty (THA), and to provide a web calculator for clinical usage. Methods. We included 53,099 patients with cemented THA due to osteoarthritis from the Swedish Hip Arthroplasty Registry for model derivation and internal validation, as well as 125,428 patients from England and Wales recorded in the National Joint Register for England, Wales, Northern Ireland, the Isle of Man, and the States of Guernsey (NJR) for external model validation. A model was developed using a bootstrap ranking procedure with a least absolute shrinkage and selection operator (LASSO) logistic regression model combined with piecewise linear regression. Discriminative ability was evaluated by the area under the receiver operating characteristic curve (AUC). Calibration belt plots were used to assess model calibration. Results. A main effects model combining age, sex, American Society for Anesthesiologists (ASA) class, the presence of cancer, diseases of the central nervous system, kidney disease, and diagnosed obesity had good discrimination, both internally (AUC = 0.78, 95% confidence interval (CI) 0.75 to 0.81) and externally (AUC = 0.75, 95% CI 0.73 to 0.76). This model was superior to traditional models based on the Charlson (AUC = 0.66, 95% CI 0.62 to 0.70) and Elixhauser (AUC = 0.64, 95% CI 0.59 to 0.68) comorbidity indices. The model was well calibrated for predicted probabilities up to 5%. Conclusion. We developed a parsimonious model that may facilitate individualized risk assessment prior to one of the most common surgical interventions. We have published a web calculator to aid clinical decision-making. Cite this article: Bone Joint J 2021;103-B(3):469–478

Aims. The aim of this study was to investigate whether the use of antibiotic-loaded bone cement influenced the risk of revision surgery after primary total hip arthroplasty (THA) for osteoarthritis. Methods. The study involved data collected by the National Joint Registry (NJR) for England and Wales, Northern Ireland and the Isle of Man between 1 September 2005 and 31 August 2017. Cox proportional hazards were used to investigate the association between use of antibiotic-loaded bone cement and the risk of revision due to prosthetic joint infection (PJI), with adjustments made for the year of the initial procedure, age at the time of surgery, sex, American Society of Anesthesiologists (ASA) grade, head size, and body mass index (BMI). We looked also at the association between use of antibiotic-loaded bone cement and the risk of revision due to aseptic loosening or osteolysis. Results. The cohort included 418,857 THAs of whom 397,896 had received antibiotic-loaded bone cement and 20,961 plain cement. After adjusting for putative confounding factors, the risk of revision for PJI was lower in those in whom antibiotic-loaded bone cement was used (hazard ration (HR) 0.79; 95% confidence interval (CI) 0.64 to 0.98). There was also a protective effect on the risk of revision due to aseptic loosening or osteolysis, in the period of > 4.1 years after primary THA, HR 0.57, 95% CI 0.45, 0.72. Conclusion. Within the limits of registry analysis, this study showed an association between the use of antibiotic-loaded bone cement and lower rates of revision due to PJI. The findings support the continued use of antibiotic-loaded bone cement in cemented THA. Cite this article: Bone Joint J 2020;102-B(8):997–1002