Adjusting expected deaths for mortality displacement during the COVID-19 pandemic: a model based counterfactual approach at the level of individuals.

BACKGROUND: Near-real time surveillance of excess mortality has been an essential tool during the COVID-19 pandemic. It remains critical for monitoring mortality as the pandemic wanes, to detect fluctuations in the death rate associated both with the longer-term impact of the pandemic (e.g. infection, containment measures and reduced service provision by the health and other systems) and the responses that followed (e.g. curtailment of containment measures, vaccination and the response of health and other systems to backlogs). Following the relaxing of social distancing regimes and reduction in the availability of testing, across many countries, it becomes critical to measure the impact of COVID-19 infection. However, prolonged periods of mortality in excess of the expected across entire populations has raised doubts over the validity of using unadjusted historic estimates of mortality to calculate the expected numbers of deaths that form the baseline for computing numbers of excess deaths because many individuals died earlier than they would otherwise have done: i.e. their mortality was displaced earlier in time to occur during the pandemic rather than when historic rates predicted. This is also often termed "harvesting" in the literature. METHODS: We present a novel Cox-regression-based methodology using time-dependent covariates to estimate the profile of the increased risk of death across time in individuals who contracted COVID-19 among a population of hip fracture patients in England (N = 98,365). We use these hazards to simulate a distribution of survival times, in the presence of a COVID-19 positive test, and then calculate survival times based on hazard rates without a positive test and use the difference between the medians of these distributions to estimate the number of days a death has been displaced. This methodology is applied at the individual level, rather than the population level to provide a better understanding of the impact of a positive COVID-19 test on the mortality of groups with different vulnerabilities conferred by sociodemographic and health characteristics. Finally, we apply the mortality displacement estimates to adjust estimates of excess mortality using a "ball and urn" model. RESULTS: Among the exemplar population we present an end-to-end application of our methodology to estimate the extent of mortality displacement. A greater proportion of older, male and frailer individuals were subject to significant displacement while the magnitude of displacement was higher in younger females and in individuals with lower frailty: groups who, in the absence of COVID-19, should have had a substantial life expectancy. CONCLUSION: Our results indicate that calculating the expected number of deaths following the first wave of the pandemic in England based solely on historical trends results in an overestimate, and excess mortality will therefore be underestimated. Our findings, using this exemplar dataset are conditional on having experienced a hip fracture, which is not generalisable to the general population. Fractures that impede mobility in the weeks that follow the accident/surgery considerably shorten life expectancy and are in themselves markers of significant frailty. It is therefore important to apply these novel methods to the general population, among whom we anticipate strong patterns in mortality displacement - both in its length and prevalence - by age, sex, frailty and types of comorbidities. This counterfactual method may also be used to investigate a wider range of disruptive population health events. This has important implications for public health monitoring and the interpretation of public health data in England and globally.

Hip Arthroscopy for Femoroacetabular Impingement Is Associated With Improved Sexual Function And Quality of Life.

PURPOSE: The purpose of this study was to investigate changes in sexual function and activity after arthroscopic hip surgery for femoroacetabular impingement using the United Kingdom Non-Arthroplasty Hip Registry dataset. Subanalyses were performed between males and females, and patients over 40 and under 40 years old. METHODS: Patients who had arthroscopic hip surgery between January 1, 2012, and October 31, 2020, were aged over 16, and completed the relevant patient-reported outcome measures were included. Question 9 of the International Hip Outcome Tool-12 (sexual activity question [SAQ]) refers to problems with sexual activity, and responses to this were compared before surgery and at 6 and 12 months after surgery. Subanalyses were also performed, including SAQ scores by patients' sex or age. SAQ scores were correlated with Euroqol-5 dimension-5 level self-reporting tool (EQ-5D-5L) scores using Spearman's rank coefficient. RESULTS: SAQ was answered by 2,547 patients before and at 6 months after surgery (62.3% female, median age = 36.2, interquartile range [IQR] = 29-44 years) and by 2,314 at 12 months (61.9% female, median age = 36.2, IQR = 29-44 years). Scores for sexual activity increased from 35.0 before surgery to 70.0 at 6 months (P < .001) and were maintained at 12 months (P < .001). Female patients demonstrated a significantly greater improvement in their scores for sexual function from before surgery (median = 30.0, IQR = 14-50) to 6 months (median = 60, IQR = 28-86, P < .001) and 12 months (median = 62.0, IQR = 29-90, P < .001), compared to male patients (preoperative median = 50.0, IQR 25-84; 6-month median = 80, IQR = 45-97; 12-month median = 80, IQR = 41-98). The effect of age on improvements in sexual function did not demonstrate a significant difference. A significant positive correlation was found between improvements in sexual function and quality of life, as measured by the EQ-5D-5L, at 6 and 12 months (P < .001). CONCLUSION: Hip arthroscopy for symptomatic femoroacetabular impingement produces an improvement in sexual function and activity. Scores for sexual function improved regardless of patient age or sex; however, female patients experienced a greater improvement in sexual function than males. LEVEL OF EVIDENCE: Level III (Retrospective cohort study).

Hip arthroscopy for femoroacetabular impingement is associated with significant improvement in early patient reported outcomes: analysis of 4963 cases from the UK non-arthroplasty registry (NAHR) dataset.

PURPOSE: Results from recent randomised controlled trials demonstrate the superiority of surgery over physiotherapy in patients with femoroacetabular impingement (FAI) of the hip in early follow-up. However, there is paucity of evidence regarding which factors influence outcomes of FAI surgery, particularly notable is the lack of information on the effect of impingement subtype (cam or pincer or mixed) on patient reported outcomes measures (PROMs). This study aims to evaluate the early outcomes of hip arthroscopy for FAI, and their determinants. METHODS: This is a retrospective analysis of prospectively collected data from the UK Non-Arthroplasty Hip Registry (NAHR) of patients undergoing arthroscopic intervention for FAI between 2012 and 2019. The null hypothesis was that there is no difference in PROMs, based on morphological subtype of FAI treated or patient characteristics, at each follow-up timepoint. The outcome measures used for the study were the iHOT-12 score and the EQ5D Index and VAS 6- and 12-month follow-up. RESULTS: A cohort of 4963 patients who underwent arthroscopic treatment of FAI were identified on the NAHR database. For all FAI pathology groups, there was significant improvement from pre-operative PROMs when compared to those at 6 and 12 months. Overall, two-thirds of patients achieved the minimum clinically important difference (MCID), and almost half achieved substantial clinical benefit (SCB) for iHOT-12 by 12 months. Pre-operatively, and at 12-month follow-up, iHOT-12 scores were significantly poorer in the pincer group compared to the cam and mixed pathology groups (p < 0.01). Multivariable analysis revealed PROMS improvement in the setting of a higher-grade cartilage lesion. CONCLUSION: This registry study demonstrates that hip arthroscopy is an effective surgical treatment for patients with symptomatic FAI and results in a statistically significant improvement in PROMs which are maintained through 12 months follow-up. LEVEL OF EVIDENCE: III.

Ceramic Bearings Are Associated With a Significantly Reduced Revision Rate in Primary Hip Arthroplasty: An Analysis From the National Joint Registry for England, Wales, Northern Ireland, and the Isle of Man.

BACKGROUND: Prosthetic joint infection (PJI) is a devastating complication. Studies have suggested reduction in PJI with the use of ceramic bearings. METHODS: Adult patients who underwent total hip arthroplasty (THA) using an uncemented acetabular component with ceramic-on-ceramic (CoC), ceramic-on-polyethylene (CoP), or metal-on-polyethylene (MoP) bearing surfaces between 2002 and 2016 were extracted from the National Joint Registry for England, Wales, Northern Ireland, and the Isle of Man. A competing risk regression model to investigate predictors of each revision outcome was used. Time-to-event was determined by duration of implantation since primary surgery with competing risks being death or revision. The results were adjusted for age, gender, American Association of Anaesthesiologists grade, body mass index, surgical indication, intraoperative complications, and implant data. RESULTS: In total, 456,457 THAs (228,786 MoP, 128,403 CoC, and 99,268 CoP) were identified. Multivariable modeling showed that the risk of revision for PJI was significantly lower with CoC (risk ratio 0.748, P < .001) and CoP (risk ratio 0.775, P < .001) compared to MoP. Significant reduction in risk of aseptic and all-cause revision was also seen. The significant protective effect of ceramic bearing was predominantly seen 2 years after implantation. Aseptic revision beyond 2 years reduced by 18.1% and 24.8% for CoC and CoP (P < .001), respectively. All-cause revision rate beyond 2 years reduced by 21.6% for CoC and 27.1% for CoP (P < .001) CONCLUSION: This study demonstrates an association between the use of ceramic as part of the bearing, with lower rates of revision for all causes, revision for infection, and revision for aseptic causes, supporting ceramic bearings in THA.

Staphylococcal resistance profiles in deep infection following primary hip and knee arthroplasty: a study using the NJR dataset.

INTRODUCTION: This study aimed to (1) report the rates of resistance against a variety of antibiotics for pure Staphylococcal infections, and (2) examine the impact of ALBC use at primary surgery has on resistance patterns for patients undergoing first-time revision of primary hip and knee arthroplasty for indication of infection. MATERIALS AND METHODS: Data from the National Joint Registry database for England and Wales were linked to microbiology data held by Public Health England to identify a consecutive series of 258 primary hip and knee arthroplasties performed between April 2003 and January 2014 that went on to have a revision for Staphylococcal deep periprosthetic infection. Multivariate binary logistic regression was used to study predictors of microorganism resistance to a range of antimicrobials. RESULTS: After adjusting for patient and surgical factors, multivariate analysis showed the use of gentamicin-loaded bone cement at the primary surgery was associated with a significant increase in the risk of Staphylococcal gentamicin resistance (odds ratio 8.341, 95% CI 2.297-30.292, p = 0.001) and methicillin resistance (odds ratio 3.870, 95% CI 1.319-11.359, p = 0.014) at revision for infection. CONCLUSIONS: Clinicians must anticipate the possibility of antibiotic resistance to ALBC utilised at primary surgery.

Microbial resistance related to antibiotic-loaded bone cement: a historical review.

PURPOSE: The use of antibiotic-loaded bone cement (ALBC) has a range of indications for use in orthopaedics. It has the advantage of delivering high loads of antibiotics to a targeted site, thereby avoiding the side effects associated with systemic administration. However, there is concern that the use of ALBC may precipitate the development of antibiotic-resistant bacteria. METHODS: This review focuses on (1) the published research using both animal and human models examining the association between ALBC and the induction of microbial resistance (2) the mechanisms by which antimicrobial resistance develop (3) the research pertaining to specific classes of antibiotics commonly used in orthopaedic practice (4) the recent developments in calcium sulphate beads, nanoparticles and chitosan, as alternative antimicrobial treatments for periprosthetic joint infections. CONCLUSION: The literature for and against a link between ALBC and the development of microbiological resistance is reviewed and presented. It is concluded that further research is needed to develop a defined set of indications for the use of ALBC in the management of periprosthetic joint infection. In addition, further research into alternative antimicrobial therapies in this area should be encouraged.

Does pre-operative sampling predict intra-operative cultures and antibiotic sensitivities in knee replacements revised for infection?: a study using the NJR dataset.

PURPOSE: This study examined a cohort of primary knee arthroplasties revised for peri-prosthetic infection to (1) determine whether the microorganisms isolated by sampling (up to 6 months pre-operatively) are representative of the microorganisms encountered at the time of knee revision, (2) determine whether the antibiotic sensitivity profiles of matching organisms correlate and (3) determine whether the proportion of organism and antibiotic sensitivity matches is influenced by the type of infection, timing of sample collection and the type of microorganism isolated. METHODS: From the National Joint Registry database for England and Wales, a consecutive series of primary knee arthroplasties performed between 2003 and 2014 that went on to have a revision for peri-prosthetic infection were identified. Each case was then linked to a national microbiology database held by Public Health England. Following data linkage, intra-operative and pre-operative cultures were identified and compared in a group of 75 patients. RESULTS: Pre-operative genus matched intra-operative genus in 56 of 75 cases (75 %). Of those 56, the corresponding antimicrobial sensitivities matched in 37 (66 % of cases). Overall, 37 of 75 cases (49 %) matched for both microorganism and antimicrobial sensitivity. The proportion of matches was highest in the pure Staphylococcal genus infections (genus match 88 %, sensitivity match 62 %, genus and sensitivity match 55 %) and lowest in those patients with mixed organism infections (genus match 29 %, sensitivity match 14 %). CONCLUSION: Pre-operative joint sampling obtained by either aspiration or tissue biopsy is advocated in cases where peri-prosthetic infection is suspected and provides the only means of determining infecting organism prior to revision. Overall, only half of all pre-operative cultures matched completely the findings of intra-operative samples in terms of both the microorganism(s) encountered and their corresponding antimicrobial sensitivity profile. Clinicians should be vigilant regarding the possibility of the patient acquiring further microorganisms or the development of new antibiotic resistance by the time of revision, especially in historic pre-operative cultures. Broad spectrum antibiotic therapies should therefore be employed until final microorganisms and antimicrobial sensitivities are confirmed from intra-operative samples. LEVEL OF EVIDENCE: IV.

Microorganisms responsible for periprosthetic knee infections in England and Wales.

PURPOSE: This study aimed to delineate epidemiology of infecting microorganism genus in first-time revision knee arthroplasty for indication of periprosthetic joint infection in England and Wales using linked registry data. METHODS: From the National Joint Registry database for England and Wales, a consecutive series of primary knee arthroplasties performed between April 2003 and January 2014 that went on to have a revision for periprosthetic infection were identified (n = 2810). Each case was then linked to microbiology data held by Public Health England in order to identify infecting microorganism at time of revision surgery established from intra-operative cultures. Following data linkage, 403 culture results at time of revision surgery were identified in a group of 331 patients. The demographic characteristics of five microorganism groups were compared: pure staphylococcus (single genus), pure streptococcus (single genus), other gram-positive infections (single genus), gram-negative infections (single genus) and mixed genus infections. RESULTS: Staphylococcus species was the most common organism genus isolated after revision of a primary implant for infection and present in 72 % of cases overall (71.3 % of patients with a single-genus infection and 76.8 % of patients with mixed genus infection). A pure staphylococcal infection was present in 59 % of all cases. A single-genus infection was responsible for infection in 83.1 % of cases, and mixed genera were responsible in 16.9 % of cases. A significant difference was observed for mean age at primary procedure in the cohort of patients where there was an isolated pure streptococcal infection (73.2 years) when compared to gram-negative infections (65.0 years). No other significant differences were observed between microorganism groups in terms of BMI, gender, ASA grade, indication for primary procedure and primary implant characteristics. CONCLUSION: Staphylococci were the most commonly isolated organism species responsible for periprosthetic infection of primary arthroplasty in England and Wales. This information can be used by surgeons to benchmark and audit their own practice against national, publicly available data. Furthermore, this study has shown that even when using the largest national databases available, there is a substantial volume of missing data. Antimicrobial resistance represents a growing clinical problem with significant health and social costs. In order to counteract this threat, this study would advocate the consolidation of national microbial data in order to guide effective strategies towards targeting and combating the threat of antimicrobial resistance. LEVEL OF EVIDENCE: IV.

Changes in surface topography at the TKA backside articulation following in vivo service: a retrieval analysis.

PURPOSE: With the advent of modular total knee arthroplasty (TKA) systems, backside wear at the articulation between the ultra-high-molecular-weight-polyethylene (UHMWPE) component undersurface and the tibial baseplate has received increasing attention as a source of clinically significant polyethylene wear debris. The aim of this study was to investigate the reciprocating interface at the TKA undersurface articulation using profilometry after in vivo service. Our null hypothesis was that there would be no discernible pattern or relationship between the metal tibial baseplate and UHMWPE surface profile. METHODS: A nanoscale analysis of thirty retrieved fixed-bearing TKA explants was performed. Surface roughness (Sa) and skewness (Ssk) were measured on both the UHMWPE component undersurface and the tibial baseplate of explants using a non-contacting profilometer (1 nm resolution). Four pristine unimplanted components of two different designs (Stryker Kinemax and DePuy PFC) were examined for control purposes. RESULTS: Mean explant baseplate surface roughness was 1.24 µm (0.04-3.01 µm). Mean explant UHMWPE undersurface roughness was 1.16 µm (0.23-2.44 µm). Each explant had an individual roughness pattern with unique baseplate and undersurface UHMWPE surface roughness that was different from, but closely related to, surface topography observed in control implants of the same manufacturer and design. Following in vivo service, UHMWPE undersurface showed changes towards a negative skewness, demonstrating that wear is occurring at the backside interface. CONCLUSION: In vivo loading of the TKA prosthesis leads to measurable changes in surface profile at the backside articulation, which appear to be dependent on several factors including implant design and in vivo duration. These findings are consistent with wear occurring at this surface. Findings of this study would support the use of a polished tibial tray over an unpolished design in total knee arthroplasty with the goal of reducing PE wear by means of providing a smoother backside countersurface for the UHMWPE component.

Consultant revision hip arthroplasty volumes and new consultant volume trajectories in England, Wales, Northern Ireland, and the Isle of Man.

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.

Comparison of early outcomes of arthroscopic labral repair or debridement : a study using the UK Non-Arthroplasty Hip Registry dataset.

AIMS: This study uses prospective registry data to compare early patient outcomes following arthroscopic repair or debridement of the acetabular labrum. METHODS: Data on adult patients who underwent arthroscopic labral debridement or repair between 1 January 2012 and 31 July 2019 were extracted from the UK Non-Arthroplasty Hip Registry. Patients who underwent microfracture, osteophyte excision, or a concurrent extra-articular procedure were excluded. The EuroQol five-dimension (EQ-5D) and International Hip Outcome Tool 12 (iHOT-12) questionnaires were collected preoperatively and at six and 12 months post-operatively. Due to concerns over differential questionnaire non-response between the two groups, a combination of random sampling, propensity score matching, and pooled multivariable linear regression models were employed to compare iHOT-12 improvement. RESULTS: A total of 2,025 labral debridements (55%) and 1,659 labral repairs (45%) were identified. Both groups saw significant (p < 0.001) EQ-5D and iHOT-12 gain compared to preoperative scores at 12 months (iHOT-12 improvement: labral repair = +28.7 (95% confidence interval (CI) 26.4 to 30.9), labral debridement = +24.7 (95% CI 22.5 to 27.0)), however there was no significant difference between procedures after multivariable modelling. Overall, 66% of cases achieved the minimum clinically important difference (MCID) and 48% achieved substantial clinical benefit at 12 months. CONCLUSION: Both labral procedures were successful in significantly improving early functional outcome following hip arthroscopy, regardless of age or sex. Labral repair was associated with superior outcomes in univariable analysis, however there was no significant superiority demonstrated in the multivariable model. Level of evidence: III Cite this article: Bone Jt Open 2022;3(4):291-301.

The impact of COVID-19 on mortality after hip fracture : a population cohort study from England.

AIMS: Hip fracture commonly affects the frailest patients, of whom many are care-dependent, with a disproportionate risk of contracting COVID-19. We examined the impact of COVID-19 infection on hip fracture mortality in England. METHODS: We conducted a cohort study of patients with hip fracture recorded in the National Hip Fracture Database between 1 February 2019 and 31 October 2020 in England. Data were linked to Hospital Episode Statistics to quantify patient characteristics and comorbidities, Office for National Statistics mortality data, and Public Health England's SARS-CoV-2 testing results. Multivariable Cox regression examined determinants of 90-day mortality. Excess mortality attributable to COVID-19 was quantified using Quasi-Poisson models. RESULTS: Analysis of 102,900 hip fractures (42,630 occurring during the pandemic) revealed that among those with COVID-19 infection at presentation (n = 1,120) there was a doubling of 90-day mortality; hazard ratio (HR) 2.09 (95% confidence interval (CI) 1.89 to 2.31), while the HR for infections arising between eight and 30 days after presentation (n = 1,644) the figure was greater at 2.51 (95% CI 2.31 to 2.73). Malnutrition (1.45 (95% CI 1.19 to 1.77)) and nonoperative treatment (2.94 (95% CI 2.18 to 3.95)) were the only modifiable risk factors for death in COVID-19-positive patients. Patients who had tested positive for COVID-19 more than two weeks prior to hip fracture initially had better survival compared to those who contracted COVID-19 around the time of their hip fracture; however, survival rapidly declined and by 365 days the combination of hip fracture and COVID-19 infection was associated with a 50% mortality rate. Between 1 January and 30 June 2020, 1,273 (99.7% CI 1,077 to 1,465) excess deaths occurred within 90 days of hip fracture, representing an excess mortality of 23% (99.7% CI 20% to 26%), with most deaths occurring within 30 days. CONCLUSION: COVID-19 infection more than doubles the rate of early hip fracture mortality. Those contracting infection between 8 and 30 days after initial presentation are at even higher mortality risk, signalling the potential for targeted interventions during this period to improve survival.Cite this article: Bone Joint J 2022;104-B(10):1156-1167.

Periacetabular Osteotomy for Developmental Dysplasia of the Hip and Femoroacetabular Impingement: A Study Using the U.K. Non-Arthroplasty Hip Registry (NAHR) Data Set.

BACKGROUND: Periacetabular osteotomy (PAO) is a well-recognized procedure for the treatment of hip dysplasia in young adults and can be used for the surgical management of femoroacetabular impingement (FAI) with acetabular retroversion. The aim of this study was to use a national database to assess the outcomes of PAO for developmental dysplasia of the hip (DDH) and for FAI. METHODS: All patients in whom an isolated PAO had been performed between January 2012 and February 2019 were identified in the Non-Arthroplasty Hip Registry (NAHR). Their outcomes were assessed using the EuroQol-5 Dimensions (EQ-5D) index and the International Hip Outcome Tool (iHOT)-12 preoperatively and then at 6 months, 12 months, and 2 years postoperatively. RESULTS: Six hundred and thirty (630) PAOs were identified, with 558 (89%) performed for DDH and 72 (11%) performed for FAI. Most patients (90%) were female. The mean age in the DDH group (31.2 years) was significantly higher (p < 0.0001) than that in the FAI group (26.5 years). There were no other significant between-group demographic differences. Preoperatively and at each follow-up time-period, iHOT-12 scores were better in the DDH group than in the FAI group; however, only the preoperative scores differed significantly. There was significant improvement between the preoperative and 6-month iHOT-12 and EQ-5D index scores in both the DDH and the FAI group. This improvement was maintained at 12 months postoperatively, by which time almost 90% of the patients had achieved the minimum clinically important difference (MCID) in their iHOT-12 score. CONCLUSIONS: This study shows that PAO is a successful surgical intervention for DDH and FAI in the short term, with significant improvement in patient-reported outcome scores that is maintained up to 2 years postoperatively. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Methicillin sensitive staphylococcus aureus screening and decolonisation in elective hip and knee arthroplasty.

AIMS: Periprosthetic joint infection (PJI) is a catastrophic and potentially life threatening complication following arthroplasty. In addition to the resulting impact on patient morbidity and mortality, PJI is associated with significant financial cost, which is estimated at £21,937 per case. Methicillin sensitive staphylococcus aureus (MSSA) is a common isolate in PJI and colonisation is a proven risk factor for subsequent infection. The aims of this study were: (1) to determine if MSSA screening and decolonisation reduced MSSA PJI rate in primary joint replacement and (2) to determine cost effectiveness of such a screening program. METHODS: Pre-operative screening for MSSA was introduced in our institution in 2010. All MSSA positive patients attending for elective arthroplasty were prescribed Octenisan body wash and nasal Bactroban for use 5 days prior to procedure, and five days after. Infection data was collected prospectively and compared with a control group from before. RESULTS: Between 2007 and 2014, 12,910 primary arthroplasties (5917 hip, 6993 knee) were performed. There were 3593 in the pre-screening group and 9318 in the post-screening group. Pre-screening PJI MSSA rate was 0.75% which reduced to 0.25% post screening introduction (p < 0.0001). Overall PJI rate fell from 1.92% to 1.41% (p = 0.03). The screening program was most effective in MSSA prevention in total hip arthroplasty (3% to 1.5%, p = 0.002) and significant in the multivariate analysis. Following the introduction of the screening programme 47 PJIs were avoided, with a cost per infection prevented of £1893. CONCLUSION: The MSSA screening and eradication protocol used in our institution was effective at reducing rates of MSSA PJI. Furthermore, it resulted in significant savings when compared to the cost of prevented infections.

Analysis of causative microorganism in 248 primary hip arthroplasties revised for infection: a study using the NJR dataset.

INTRODUCTION: This study aimed to describe the epidemiology of the causative organism in a series of primary hip arthroplasties revised for a diagnosis of periprosthetic joint infection (PJI) in England and Wales. METHODS: Patient data from the National Joint Registry (NJR) was linked to microbiology data held by Public Health England (PHE) which identified a series of 248 primary hip arthroplasties revised for PJI between 2003 and 2014. Definitive cultures, isolated at time of revision surgery, were available for all cases. Total hip arthroplasty (n = 239, 96%) and hip resurfacing (n = 5, 2%) were the most commonly performed primary procedures. A two-stage revision was the most common operative management (n = 174, 70%). RESULTS: 202 (81%) cases were infected with a single genus microorganism and the most commonly implicated genus was Staphylococcus species (70% of all single genus infections). Staphylococcus species were also the most commonly identified microorganism in mixed genus infections (74% of patient's cultures). There was a significant difference in microorganism distribution when comparing uncemented vs cement implant fixation, with a higher incidence of Gram-negative infection observed in the uncemented group (p = 0.048, Chi-square). CONCLUSIONS: Both prophylactic and therapeutic antibiotic regimes should be focused on targeting Staphylococci.