Aims. Current treatments of prosthetic joint infection (PJI) are minimally effective against Staphylococcus aureus biofilm. A murine PJI model of debridement, antibiotics, and implant retention (DAIR) was used to test the hypothesis that PlySs2, a bacteriophage-derived lysin, can target S. aureus biofilm and address the unique challenges presented in this periprosthetic environment. Methods. The ability of PlySs2 and vancomycin to kill biofilm and colony-forming units (CFUs) on orthopaedic implants were compared using in vitro models. An in vivo murine PJI model of DAIR was used to assess the efficacy of a combination of PlySs2 and vancomycin on periprosthetic bacterial load. Results. PlySs2 treatment reduced 99% more CFUs and 75% more biofilm compared with vancomycin in vitro. A combination of PlySs2 and vancomycin in vivo reduced the number of CFUs on the surface of implants by 92% and in the periprosthetic tissue by 88%. Conclusion. PlySs2 lysin was able to reduce biofilm, target planktonic bacteria, and work synergistically with vancomycin in our in vitro models. A combination of PlySs2 and vancomycin also reduced bacterial load in periprosthetic tissue and on the surface of implants in a murine model of DAIR treatment for established PJI. Cite this article: Bone Joint J 2020;102-B(7 Supple B):3–10

Objectives. We used the National Joint Registry for England, Wales, Northern Ireland and the Isle of Man (NJR) to investigate the risk of revision due to prosthetic joint infection (PJI) for patients undergoing primary and revision hip arthroplasty, the changes in risk over time, and the overall burden created by PJI. Methods. We analysed revision total hip arthroplasties (THAs) performed due to a diagnosis of PJI and the linked index procedures recorded in the NJR between 2003 and 2014. The cohort analysed consisted of 623 253 index primary hip arthroplasties, 63 222 index revision hip arthroplasties and 7585 revision THAs performed due to a diagnosis of PJI. The prevalence, cumulative incidence functions and the burden of PJI (total procedures) were calculated. Overall linear trends were investigated with log-linear regression. Results. We demonstrated a prevalence of revision THA due to prosthetic joint infection of 0.4/100 procedures following primary and 1.6/100 procedures following revision hip arthroplasty. The prevalence of revision due to PJI in the three months following primary hip arthroplasty has risen 2.3-fold (95% confidence interval (CI) 1.3 to 4.1) between 2005 and 2013, and 3.0-fold (95% CI 1.1 to 8.5) following revision hip arthroplasty. Over 1000 procedures are performed annually as a consequence of hip PJI, an increase of 2.6-fold between 2005 and 2013. Conclusions. Although the risk of revision due to PJI following hip arthroplasty is low, it is rising and, coupled with the established and further predicted increased incidence of both primary and revision hip arthroplasty, this represents a growing and substantial treatment burden. Cite this article: E. Lenguerrand, M. R. Whitehouse, A. D. Beswick, S. A. Jones, M. L. Porter, A. W. Blom. Revision for prosthetic joint infection following hip arthroplasty: Evidence from the National Joint Registry. Bone Joint Res 2017;6:391–398. DOI: 10.1302/2046-3758.66.BJR-2017-0003.R1

Aims. Prosthetic joint infection (PJI) and aseptic loosening in total hip arthroplasty (THA) can present with pain and osteolysis. The Musculoskeletal Infection Society (MSIS) has provided criteria for the diagnosis of PJI. The aim of our study was to analyze the utility of F18-fluorodeoxyglucose (FDG) positron emission tomography (PET) CT scan in the preoperative diagnosis of septic loosening in THA, based on the current MSIS definition of prosthetic joint infection. Patients and Methods. A total of 130 painful unilateral cemented THAs with a mean follow-up of 5.17 years (. sd. 1.12) were included in this prospective study. The mean patient age was 67.5 years (. sd. 4.85). Preoperative evaluation with inflammatory markers, aspiration, and an F18 FDG PET scan were performed. Diagnostic utility tests were also performed, based on the MSIS criteria for PJI and three samples positive on culture alone. Results. The mean erythrocyte sedimentation rate, C-reactive protein, and white cell count were 47.83 mm/hr, 25.21 mg/l, and 11.05 × 10. 9. /l, respectively. The sensitivity, specificity, accuracy, negative predictive value, and false-positive rate of FDG PET compared with MSIS criteria were 94.87%, 38.46 %, 56.38%, 94.59 %, and 60.21%, respectively. The false-positive rate of FDG PET compared with culture alone was 77.4%. Conclusion. FDG PET has a definitive role in the preoperative evaluation of suspected PJI. This the first study to evaluate its utility based on MSIS criteria and compare it with microbiology results alone. However, FDG PET has a high false-positive rate. Therefore, we suggest that F18 FDG PET is useful in confirming the absence of infection, but if positive, may not be confirmatory of PJI. Cite this article: Bone Joint J 2019;101-B:910–914

The management of prosthetic joint infection (PJI) has been widely performed for total hip arthroplasties (THA), but none has compared it with hip resurfacing arthroplasty (RSA). We also carried out a retrospective case-control study comparing the surgical treatment of PJI by surgical debridement and implant retention between RSA and THA in order to clarify whether there was a difference in terms of (1) successful healing of PJI (2) functional scores after recovery (3) risk factors for recurrence of PJI. Our hypothesis was that simple debridement with prosthesis retention regardless of the timeframe allowed to obtain a higher success rate for RSA compared to THA. From 2010 to 2018, a single-center case-control study based on 3056 RSA found 13 PJI were age-matched (based on the 139 THA PJI treated) with 15 THA PJI (mean age of 53 years old (47–58) for THA and 59 (45–66) for RSA (p=0.34)). We compared their survival (absence of infectious recurrence) and the means differences between the 2 groups (demographical, clinical and biological data). There was no difference between the 2 groups concerning: age (p=0.3), BMI (p=0.4), initial diagnosis (p=0.4), operating time for primary surgery (p=0.3), the presence of a postoperative hematoma (p=0.4), the type of bacteria (p=0.5), the total duration of antibiotic therapy (p=0.9) and the type of antibiotic therapy (p=0.6). Early postoperative infections (less than 6 weeks) occurred in 7/13 RSA cases (54%) compared to 11/15 THA cases (73%). At the mean follow-up of 5 years (2–7), the success rate without recurrence was significantly higher in the RSA group 100% versus 66.7% (10/15) for the THA group (p=0.044). At the last follow-up, the Oxford Hip Score was higher in the RSA versus THA group's (14 versus 22 p=0.004). Simple surgical debridement an RSA without changing implants after PJI can be done regardless of the time to onset of infection. This is secondary to the absence of metaphyseal bone invasion and the low content of joint fluid

Aims. The increasing infection burden after total hip arthroplasty (THA) has seen a rise in the use of two-stage exchange arthroplasty and the use of increasingly powerful antibiotics at the time of this procedure. As a result, there has been an increase in the number of failed two-stage revisions during the past decade. The aim of this study was to clarify the outcome of repeat two-stage revision THA following a failed two-stage exchange due to recurrent prosthetic joint infection (PJI). Patients and Methods. We identified 42 patients who underwent a two-stage revision THA having already undergone at least one previous two stage procedure for infection, between 2000 and 2015. There were 23 women and 19 men. Their mean age was 69.3 years (48 to 81). The outcome was analyzed at a minimum follow-up of two years. Results. A satisfactory control of infection and successful outcome was seen in 26 patients (57%). There therefore remained persistent symptoms that either required further surgery or chronic antibiotic suppression in 16 patients (38%). One-third of patients had died by the time of two years’ follow-up. Conclusion. The rate of failure and complication rate of repeat two-stage exchange THA for PJI is high and new methods of treatment including host optimization, immunomodulation, longer periods between stages, and new and more powerful forms of antimicrobial treatment should be investigated. Cite this article: Bone Joint J 2019;101-B(6 Supple B):110–115

Introduction. The infection rate after total joint arthroplasty (TJA) has been shown to be 1–2% in multiple series and registry data. Irrigation, debridement, and polyethylene exchange (IDPE) is a common first line treatment in many cases of acute prosthetic joint infection (PJI). The reinfection rate in open IDPE procedures is variable with studies showing reinfection rates of 10–70% depending on various patient and microbial factors. Our pilot study aimed to determine if the bacterial load in infected total joints was sufficiently reduced by IDPE to allow for the use of post-debridement cultures as an independent marker of procedural success. Methods. 46 prosthetic joint infections underwent irrigation and debridement using 6L of normal saline and 3L of a normal saline and bacitracin mixture prior to the insertion of a new polyethylene liner. This protocol utilized a single equipment setup with all surgical members donning new gloves prior to polyethylene exchange. Between 3 and 5 intraoperative cultures were obtained both prior to and after debridement as per the surgeon's standard protocol. A two-tailed student's t-test was used to evaluate for any differences in the rate of positive culture between these two groups. Results. Of all pre- and post-debridement cultures sampled 66.5% and 60.7% of cultures were positive respectively. No significant difference in the rate of positive intraoperative culture was found between pre-debridement and post-debridement groups (p = 0.52). In 32 of 46 (69%) cases there was no difference in the total number of positive cultures despite a thorough debridement. Conclusions. Our data shows that open debridement of PJI does not provide a sterile environment, and post-debridement cultures should not be used as an independent marker of procedural success. The role of an irrigation and debridement to reduce the bacterial burden and potentiate the clearance of an infection is established but its efficacy is unclear, and the inability to create a post-debridement sterile environment is a concern

Aims. Failure of irrigation and debridement (I&D) for prosthetic joint infection (PJI) is influenced by numerous host, surgical, and pathogen-related factors. We aimed to develop and validate a practical, easy-to-use tool based on machine learning that may accurately predict outcome following I&D surgery taking into account the influence of numerous factors. Methods. This was an international, multicentre retrospective study of 1,174 revision total hip (THA) and knee arthroplasties (TKA) undergoing I&D for PJI between January 2005 and December 2017. PJI was defined using the Musculoskeletal Infection Society (MSIS) criteria. A total of 52 variables including demographics, comorbidities, and clinical and laboratory findings were evaluated using random forest machine learning analysis. The algorithm was then verified through cross-validation. Results. Of the 1,174 patients that were included in the study, 405 patients (34.5%) failed treatment. Using random forest analysis, an algorithm that provides the probability for failure for each specific patient was created. By order of importance, the ten most important variables associated with failure of I&D were serum CRP levels, positive blood cultures, indication for index arthroplasty other than osteoarthritis, not exchanging the modular components, use of immunosuppressive medication, late acute (haematogenous) infections, methicillin-resistant Staphylococcus aureus infection, overlying skin infection, polymicrobial infection, and older age. The algorithm had good discriminatory capability (area under the curve = 0.74). Cross-validation showed similar probabilities comparing predicted and observed failures indicating high accuracy of the model. Conclusion. This is the first study in the orthopaedic literature to use machine learning as a tool for predicting outcomes following I&D surgery. The developed algorithm provides the medical profession with a tool that can be employed in clinical decision-making and improve patient care. Future studies should aid in further validating this tool on additional cohorts. Cite this article: Bone Joint J 2020;102-B(7 Supple B):11–19

The infection rate after total joint arthroplasty (TJA) has been shown to be 1–2% in multiple series and registry data. Irrigation, debridement, and polyethylene exchange (IDPE) is a common first line treatment in many cases of acute prosthetic joint infection (PJI). The reinfection rate in open IDPE procedures is variable with studies showing reinfection rates of 10–70% depending on various patient and microbial factors. Our pilot study aimed to determine if the bacterial load in infected total joints was sufficiently reduced by IDPE to allow for the use of post-debridement cultures as an independent marker of procedural success. 46 prosthetic joint infections underwent irrigation and debridement using 6L of normal saline and 3L of a normal saline and bacitracin mixture prior to the insertion of a new polyethylene liner. This protocol utilized a single equipment setup with all surgical members donning new gloves prior to polyethylene exchange. Between 3 and 5 intraoperative cultures were obtained both prior to and after debridement as per the surgeon's standard protocol. A two-tailed student's t-test was used to evaluate for any differences in the rate of positive culture between these two groups. Of all pre- and post-debridement cultures sampled 66.5% and 60.7% of cultures were positive respectively. No significant difference in the rate of positive intraoperative culture was found between pre-debridement and post-debridement groups (p = 0.52). In 32 of 46 (69%) cases there was no difference in the total number of positive cultures despite a thorough debridement. Our data shows that open debridement of PJI does not provide a sterile environment, and post-debridement cultures should not be used as an independent marker of procedural success. The role of an irrigation and debridement to reduce the bacterial burden and potentiate the clearance of an infection is established but its efficacy is unclear, and the inability to create a post-debridement sterile environment is a concern

Aims. We studied the impact of direct anterior (DA) versus non-anterior (NA) surgical approaches on prosthetic joint infection (PJI), and examined the impact of new perioperative protocols on PJI rates following all surgical approaches at a single institution. Patients and Methods. A total of 6086 consecutive patients undergoing primary total hip arthroplasty (THA) at a single institution between 2013 and 2016 were retrospectively evaluated. Data obtained from electronic patient medical records included age, sex, body mass index (BMI), medical comorbidities, surgical approach, and presence of deep PJI. There were 3053 male patients (50.1%) and 3033 female patients (49.9%). The mean age and BMI of the entire cohort was 62.7 years (18 to 102, . sd. 12.3) and 28.8 kg/m. 2. (13.3 to 57.6, . sd. 6.1), respectively. Infection rates were calculated yearly for the DA and NA approach groups. Covariates were assessed and used in multivariate analysis to calculate adjusted odds ratios (ORs) for risk of development of PJI with DA compared with NA approaches. In order to determine the effect of adopting a set of infection prevention protocols on PJI, we calculated ORs for PJI comparing patients undergoing THA for two distinct time periods: 2013 to 2014 and 2015 to 2016. These periods corresponded to before and after we implemented a set of perioperative infection protocols. Results. There were 1985 patients in the DA group and 4101 patients in the NA group. The overall rate of PJI at our institution during the study period was 0.82% (50/6086) and decreased from 0.96% (12/1245) in 2013 to 0.53% (10/1870) in 2016. There were 24 deep PJIs in the DA group (1.22%) and 26 deep PJIs in the NA group (0.63%; p = 0.023). After multivariate analysis, the DA approach was 2.2 times more likely to result in PJI than the NA approach (OR 2.2 (95% confidence interval 1.1 to 3.9); p = 0.006) for the overall study period. Conclusion. We found a higher rate of PJI in DA versus NA approaches. Infection prevention protocols such as use of aspirin, dilute povidone-iodine lavage, vancomycin powder, and Gram-negative coverage may have been positively associated with diminished PJI rates observed for all approaches over time. Cite this article: Bone Joint J 2019;101-B(6 Supple B):2–8

Introduction. Fluorodeoxuglucose(FDG) Positron Emission Tomography(PET) scan is used in the diagnosis of prosthetic joint infection, when the inflammatory markers and aspiration of the joint do not establish a definitive diagnosis. The aim of our study was to analyse the utility of FDG PET scan in decision making in these patients. Methods. We performed a prospective study of patients who underwent a FDG PET scan for suspected prosthetic hip infection, between September 2013 and July 2017. We analysed the results of aspiration, culture and sensitivity, histology of intra-operative samples and inflammatory markers. Our gold standard for diagnosis of infection was 3 or more positive cultures of the same organism. Diagnostic utility statistics for FDG PET were performed. Results. 55 revisions total hip replacements were included. The mean age of the patients was 67.5±4.85 years. The mean ESR, CRP and WCC were 19.83 mm/hr, 22.21 mg/l and 9.05×10. 9. /l respectively. The sensitivity and specificity for FDG PET were 93.75% and 35.89% respectively. The positive predictive value(PPV) was 37.5% and negative predictive value(NPV) was 93.33%. The accuracy of detecting an infection was 52.7%. The false positive rate was 62.5%. Discussion. FDG PET has a large number of false positive results and low specificity. If the inflammatory markers and aspiration do not establish infection, addition of FDG PET has limited accuracy in confirming the diagnosis of prosthetic joint infection. Conclusion. FDG PET may be useful for ruling out infection, but a positive result may not indicate the presence of infection

Introduction. Prosthetic joint infection (PJI) is the leading cause of failure of primary and revision hip and knee arthroplasty. It is challenging condition which represents a growing burden on hospital resources. In-patient hospital stay for antibiotic therapy post-operatively is costly and access to out-patient IV therapy (OPAT) varies between regions. In a tertiary referral centre for revision and infection, the suitability and cost-effectiveness of Dalbavancin was reviewed as a “single-shot” therapy following DAIR or revision lower limb arthroplasty for PJI. Methods & Materials. A prospective service evaluation was carried out for consecutive patients treated for PJI of the hip or knee who received Dalbavancin. Treatment was indicated by Consultant Microbiologist advice within an MDT setting where clinical or patient factors made alternative therapies eg. OPAT inappropriate. Service-level data was collected to allow calculation of bed-day savings compared to a traditional 14-day course of IV treatment. Readmission rates to the trust within 30 days were reviewed as a marker of clinical efficacy and safety. Results. 12 patients received dalbavancin for PJI. Mean bed-day saving was 6.9 (SD 3.7) per patient. A total of 83 bed days were saved compared to traditional treatment and there was a modest cost-benefit. There were no adverse reactions noted and no readmissions within 30 days. Discussion. The safety and efficacy of dalbavancin has been demonstrated in recent literature, but the impact that it can have on health-care costs and in-patient burden has not been explored. In addition, the success of out-patient therapy relies on patient engagement. In patients with co-existing cognitive difficulty or alcohol/substance use Dalbavancin offers an attractive alternative. Conclusions. The results of our pilot suggest that IV Dalbavancin is cost-effective as part of the treatment strategy for PJI and can lead to significant bed-day savings, which can assist in patient flow and departmental efficiency

Aims. The aims of this study were to characterize antibiotic choices for perioperative total knee arthroplasty (TKA) and total hip arthroplasty (THA) prophylaxis, assess antibiotic allergy testing efficacy, and determine rates of prosthetic joint infection (PJI) based on perioperative antibiotic regimen. Patients and Methods. We evaluated all patients undergoing primary TKA or THA at a single academic institution between January 2004 and May 2017, yielding 29 695 arthroplasties (22 705 patients), with 3411 arthroplasties in 2576 patients (11.5%) having undergone preoperative allergy testing. A series of institutional databases were combined to identify allergy consultation outcomes, perioperative antibiotic regimen, and infection-free survivorship until final follow-up. Results. Among 2576 allergy-tested patients, 2493 patients (97%) were cleared to use cephalosporins. For the entire cohort, 28 174 arthroplasties (94.9%) received cefazolin and 1521 (5.1%) received non-cefazolin antibiotics. Infection-free survivorship was significantly higher among arthroplasties receiving cefazolin compared with non-cefazolin antibiotics, with 0.06% higher survival free of infection at one month, 0.56% at two months, 0.61% at one year, and 1.19% at ten years (p < 0.001). Overall, the risk of PJI was 32% lower in patients treated with cefazolin after adjusting for the American Society of Anesthesiologists (ASA) classification, joint arthroplasty (TKA or THA), and body mass index (BMI; p < 0.001). The number needed to treat with cefazolin to prevent one PJI was 164 patients at one year and 84 patients at ten years. Therefore, potentially 6098 PJIs could be prevented by one year and 11 905 by ten years in a cohort of 1 000 000 primary TKA and THA patients. Conclusion. PJI rates are significantly higher when non-cefazolin antibiotics are used for perioperative TKA and THA prophylaxis, highlighting the positive impact of preoperative antibiotic allergy testing to increase cefazolin usage. Given the low rate of true penicillin allergy positivity, and the readily modifiable risk factor that antibiotic choice provides, we recommend perioperative testing and clearance for all patients presenting with penicillin and cephalosporin allergies. Cite this article: Bone Joint J 2019;101-B(6 Supple B):9–15

Joint replacement is a life-enhancing, cost-effective surgical intervention widely used to treat disabling joint pain mainly caused by osteoarthritis. Hip and knee joint replacements are common, highly successful operations bringing many patients relief from pain, and improve mobility. Prosthetic joint infections (PJI) are often difficult to diagnose; diagnosis often relying on a combination of clinical findings, microbiological data and histological evaluation of periprosthetic tissue. The majority of recent studies demonstrate a higher sensitivity for the culture of sonication fluid (62–94%) than periprosthetic tissue (55–88%). The Royal Devon & Exeter NHS Foundation Trust provided a specialist multidisciplinary team. We evaluated the use of sonication for identifying pathogens during revision hip and knee replacement in our unit with the intention of applying for further grants to study this technology in more detail; it was a diagnostic feasibility study. The target recruitment was 50 patients; 25 consecutive patients undergoing revision hip arthroplasty for any reason, and 25 undergoing revision knee arthroplasty for any reason. The majority of patients were identified in outpatient clinics. Our results show that tissue culture remains more sensitive than sonication. The sensitivity for direct sonication was 75% compared with 80% for tissue culture; sensitivity of enriched sonication was 80 %, compared to the unit results for tissue culture of 83%. The combined sensitivity of tissue culture was better as a higher number of tissue specimens were obtained. The different methodology might explain reported differences between this and other studies; however, our study does not support the use of sonication as the only tool in the diagnosis of PJI

No single test is 100% sensitive and specific for the diagnosis of prosthetic joint infection. Joint aspiration is currently the only preoperative investigation that can establish the identity of the infecting organism and its antibiotic susceptibilities. Frequently when attempting to aspirate a joint a ‘dry tap occurs as fluid cannot be aspirated. In this situation, normal saline may be injected into the joint and then reaspirated to provide fluid for culture. The aim of this study was to ascertain the diagnostic accuracy of culture of joint aspiratie with or without saline reaspiration in the event of a dry tap. A retrospective analysis of 580 hip and knee aspirations in patients deemed to have moderate-high risk of infection and ultimately proceeded to revision arthroplasty over 12 years at a large quaternary referral centre where pre operative aspiration is routine. Fluid was aspirated in 313 (54%) cases and dry taps in which saline injection reaspiration was performed occurred in 267 (46%) cases. Overall sensitivity and specificity of diagnostic aspiration were 84% (78–89%) and 85% (81–88%) respectively. Sensitivity and specificity of saline injection-reaspiration after dry tap were 87% (79–82%) and 79% (72–84%) compared to 81% (71–88%) and 90% (85–93%) for direct aspiration. Pre operative joint aspiration and culture is a sensitive and specific test for the confirmation of diagnosis in patients at a moderate to high risk of prosthetic joint infection. Culture of saline injection-reaspiration also provides accurate diagnostic information in the event of a dry tap. Both methods allow susceptibility testing of relevant organisms and are therefore able to guide peri-operative and cement instilled antibiotic therapy. Culture of pre operative joint aspirates provides sensitive and specific diagnostic information including antimicrobial susceptibility results. Saline injection-reaspiration is a useful additional technique in those patients in whom fluid cannot be aspirated

The benefits of cell salvage autotransfusion are well reported. There is a common non-evidenced belief amongst revision arthroplasty surgeons that auto-transfusion is potentially contraindicated in infected revisions.

The aim is to study the immediate and delayed outcomes of using cell saver on patients undergoing PJI surgery.

Prospective cohort service evaluation registered with the local audit department. 20 PJI cases in 18 patients where cell saver was used over a period of 4 years. Intraoperative fluid and tissue samples were taken for culture. Blood culture from salvaged blood pre and post leucodepletion filter were sent for microbiological analysis. Data on type of surgery, blood loss, further allogenic transfusion and SIRS response was collected. Success of infection clearance was assessed using 2019 MSIS ORT. Five patients receiving autologous blood in non-infection cases were used as controls.

Mean age for the PJI group was 67.7 years, 67% female. 11 patients (67%) had 1st stage surgery and 5 (25%) underwent 2nd stage whereas 4 patients had single stage surgery. The mean calculated blood loss was 1398 mls (range 400–3000mls). 6 Patients required further allogenic transfusion. 16 patients received blood via a leuco-depletion filter. The same organism grown from tissues was identified in post-filter blood in 8/17 patients (47%).

2/20 have grown a different organism in post-filtered blood, _P.Acne._

2 patients developed SIRS upon auto-transfusion, however one was thought to be secondary to cementing. The control group had 443 mls mean amount of blood loss and 1 patient developed a SIRS response.

14/20 (70%) patients had successful clearance of infection (tier 1) 2 patients died prior to undergoing 2nd stage.

Using cell saver did not impact main outcome of infection clearance in PJI surgery. We would advocate its routine usage whilst avoiding direct collection of heavily contaminated blood.

Surgical treatment of Hip PJI by resection of the infected implants and tissue and placement of a “spacer” which elutes antibiotic via antibiotic loaded cement is an accepted treatment option. There is some controversy over whether this “spacer” should be articulating or static. Proponents of the articulating option argue that there is improved function and maintenance of the soft tissue envelop. Critics have suggested that additional biomaterials may compromise eradication of infection. This study compares our results of the 2 treatment options.

A review of our institutional PJI database between 2016 and 2021 identified 87 patients who were treated with resection arthroplasty for unilateral total hip PJI. The cohort was analyzed for demographics and type for surgery, as well as medical comorbidities, survivorship, and treatment success.

44 patients were female, the mean age of all patients was 62. 44 patients were treated with Articulating apacers, and 43 patients treated with static spacers. There was no significant difference between ASA or Elixhauser score, and no significant difference between mortality or treatment failure.

This study did not show any difference between the patients who receive static spacers, from those who received articulating spacers, and deomstrated similar treatment success rates. From this data there does not appear to be any difference in success rates between those patients that were treated with static spacers and those that were treated with articulating spacers.

Introduction. Pre-operative aspiration and culture is the gold standard for the diagnosis of peri-prosthetic infection. This study aimed to ascertain the diagnostic accuracy of culture of joint aspiration with or without saline re-aspiration in the event of a dry-tap. Patients/Materials & Methods. Retrospective analysis of 343 hip aspirations in patients deemed to have moderate-high risk of infection and ultimately proceeded to revision arthroplasty over 12 years at a large quaternary referral centre where pre-operative aspiration is routine. Results. Fluid was aspirated in 141(41%) cases and dry taps in which saline injection-re-aspiration was performed occurred in 202 (59%) cases. Overall sensitivity and specificity of diagnostic aspirate were 82% (74–88%) and 79% (74–84%) respectively. Sensitivity and specificity of saline injection-re-aspiration after dry tap were 79% (64–87%) and 86% (78–92%) compared to 84% (74–91%) and 74% (66–81%) for direct aspiration. Discussion. Pre-operative joint aspiration and culture is a sensitive and specific test for the confirmation of diagnosis in patients at a moderate to high risk of prosthetic joint infection. Culture of saline injection-re-aspiration also provides accurate diagnostic information in the event of a dry tap. Both methods allow susceptibility testing of relevant organisms and are therefore able to guide peri-operative and cement instilled antibiotic therapy. Conclusions. Culture of pre-operative joint aspirates provides sensitive and specific diagnostic information, including antimicrobial susceptibility results. Saline injection-re-aspiration is a useful additional technique in those patients in whom fluid cannot be aspirated

Aims

The purpose of this study was to validate the diagnosis of periprosthetic joint infection (PJI) in the Danish Hip Arthroplasty Register (DHR).

Introduction

The value of Debridement-Antibiotics-and-Implant-Retention (DAIR) in prosthetic-joint-infection (PJI) is still a matter of debate as most studies to-date are underpowered with variable end-points. In our, tertiary referral, bone infection unit we consider DAIR to be a suitable option in all PJIs with soundly fixed prostheses, despite chronicity. The aims of this study were to define the long-term outcome following DAIR in hip PJI and identify factors that influence it.

Elevated synovial leukocyte count is a minor criterion derived from the musculoskeletal infection society (MSIS) widely used in clinical practice for diagnosis of prosthetic joint infection. There is evidence to suggest analysis within 1 hour, preferentially within 30 minutes, of aspiration reduces the risk of ex vivo cell lysis occurring during prolonged transport. Multiple site working is more common practice and the availability of a lab on site to perform these tests is not always possible. We aimed to assess whether we could safely perform synovial leukocyte counts within our cold site in the diagnosis of prosthetic joint infection. We reviewed all orthopaedic synovial fluid aspirates within the lower limb arthroplasty unit from April 2021 – April 2022 performed at South Tees NHS Foundation Trust. We assessed time from aspirate to the lab using electronic data resources. This information was compared with the labs ability to perform a synovial leukocyte count to determine the impact of delays on testing. 110 patients (34.5% hips and 63.6% knees) were identified between two sites. Time from aspirate to lab ranged from 0 mins to 26 hrs 34 mins. Mean time to processing was 3hrs 10 mins. 50% of all samples had a synovial leukocyte count performed. 67% of patients had a cell differential performed. There was no difference in the ability to perform a synovial leukocyte count between samples process in < 2hours vs > 6 hours. We conclude that it is safe practice to perform joint aspirates for the work up of periprosthetic joint infections in sites where no laboratory is immediately available as the delay to processing synovial fluid does not alter the ability to perform a synovial leukocyte count. This study will provide evidence to enable the work up of periprosthetic joint infections in cold centres and therefore reduce the delay in diagnosis and proceeding management