Peri-prosthetic joint infection (PJI) is one the most devastating complications of joint arthroplasty. Although PJI is an infrequent complication (the reported incidence is 1%-2% in the United States), it is the most common indication for revision total knee arthroplasty in the Medicare population and the third most frequent indication for revision total hip arthroplasty. Moreover, the prevalence of PJI appears to be on the rise, with a projected number exceeding 60,000 to 70,000 cases in the United States by 2020. It is estimated that more than 25% of revision procedures annually are attributed to PJI and this number is expected to increase in the upcoming years. The increase in the prevalence of obesity, diabetes, and other comorbidities among the patient population and the emergence of resistant infecting organisms are some of the reasons for the expected rise in the number of infections that medical community will witness. The challenges that PJI present to the orthopaedic community are on many fronts. Prevention of PJI has proven to be a difficult task indeed. Effective strategies for prevention of PJI are being refined. The Center for Disease Control will be publishing its updated Surgical Site Prevention Guidelines in the next few months that consists of specific recommendations for prevention of PJI. In recent years, strides are made in introducing novel molecular techniques for diagnosis of PJI, which may stand to change our practices. The current surgical technique for management of PJI, besides the immense cost, fall short of delivering high success to the patients. The major problem in eradication of infection relates to formation of biofilm on the implant surface and internalization of the organisms by affected cells. Biofilm is a sophisticated structure comprising of organisms embedded in multiple layers of glycoccalyx that allows the organisms to evade host immunity and is impenetrable to antibiotics. These organisms are capable of communicating through molecular mechanisms such as quorum sensing that affords them advantage for survival in the host environment. In recent years strategies to prevent colonization of the implant surface, an essential first step in formation of biofilm, or biofilm disruption techniques have been introduced. A recent International Consensus meeting on PJI that assembled more than 350 experts identified some of the best practices in this field and identified areas in need of future research. Moving into the future, the field of orthopaedics in general and PJI in particular stand to benefit from the discoveries in the field of molecular diagnostics, metabolomics and epigenetics

To report our experience with the use of local antibiotic co-delivery with a synthetic bone graft substitute during a second stage re-implantation of an infected proximal humeral replacement. A 72 year old man was admitted to our department with a pathological fracture through an osteolytic lesion in the left proximal humerus, due to IgG Myelomatosis. He was initially treated with a cemented proximal humerus replacement hemiarthroplasty. Peri-prosthetic joint infection (PJI) with significant joint distention was evident three weeks post operatively. Revision surgery confirmed presence of a large collection of pus and revealed disruption of the soft tissue reattachment tube, as well as complete retraction of rotator cuff and residual capsule. All modular components were removed and an antibiotic-laden cement spacer (1.8g of Clindamycin and Gentamycin, respectively) was implanted onto the well-fixed cemented humeral stem. Initial treatment with i.v. Amoxicillin/Clavulanic acid was changed to Rifampicin and Fusidic Acid during a further 8 weeks after cultures revealed growth of S. epidermidis. During second stage revision, a hybrid inverse prosthesis with silver coating was implanted, with a total of 20 ml Cerament ™G (injected into the glenoid cavity prior to insertion of the base plate and around the humeral implant-bone interface) and again stabilized with a Trevira tube. Unfortunately, this prosthesis remained unstable, ultimately requiring re-revision to a completely new constrained reverse prosthesis with a custom glenoid shell and silver-coated proximal humeral component. 18 months postoperatively, the patient's shoulder remains pain free and stable, without signs of persistent or reinfection since the initial second stage revision. The function however, unfortunately remains poor. This case report illustrates the application of an antibiotic-eluting bone graft substitute in a specific clinical situation, where co-delivery of an antibiotic together with a bone remodeling agent may be beneficial to simultaneously address PJI as well as poor residual bone quality

Aim. Advocates of Debridement-Antibiotics-and-Implant-Retention (DAIR) in hip peri-prosthetic joint infection (PJI) argue that a procedure not disturbing a sound prosthesis-bone interface is likely to lead to better survival and functional outcome compared to revision. However, no evidence supports this. This case-control study's aims were to compare outcome of DAIRs for infected 1° total hip arthroplasty (THA) with outcomes following 1° THA and 2-stage revisions of infected 1° THAs. Method. We retrospectively reviewed all DAIRs, performed for confirmed infected 1° THR (DAIR-Group, n=80), in our unit between 1997–2013. Data recorded included patient demographics, medical history, type of surgery and organism identified. Outcome measures included complications, mortality, implant survivorship and functional outcome using the Oxford Hip Score (OHS). Outcome was compared with 2 control groups matched for gender and age; a cohort of 1° THA (1°-THA-Group, n=120) and a cohort of 2-stage revisions for infection (2-Stage-Revision-Group, n=66). Results. The mean age at DAIR was 69 years and mean follow-up was 8 years (SD:5). 60% of DAIRs were for early PJI (< six weeks). Greater infection eradication with DAIR was detected with early-PJI, interval less than a week between onset of symptoms and exchange of modular components with the DAIR procedure. Infection eradication, complications and re-operation rates were similar in the DAIR- and 2-stage-revision Groups (p>0.05). For hips with successful infection eradication with DAIR, the 5-yr survival (98%) was similar to the 1°THA-Group (98%) (p=0.3). The DAIR-Group had inferior OHS (38) compared to the 1°THA-Group (42) (p=0.02) but significantly better OHS compared to the 2-stage-revision-Group (31) (p=0.008). Patients that required only one DAIR for infection eradication had similar OHS (41) to the 1° THA-Group (p=0.2). Conclusions. DAIRs are associated with similar complication and infection eradication to 2-stage revisions. Exchange of modular components is advised for improved chances of infection eradication. Functional outcome following DAIRs was better than a 2-stage revision and as good as that of a 1° THA if a single DAIR was necessary for infection eradication

Periprosthetic joint infection (PJI) is a devastating complication of total hip arthroplasty (THA). According to registry-based studies, some bearing couples are associated with an increased risk of PJI. The recent International Consensus on Periprosthetic Joint Infection stated that metal-on-metal (MOM) bearing surface appeared to be associated with a higher incidence of PJI. Based on emerging reports, the incidence of PJI appears to be different among different bearing surfaces. We conducted a multi-institutional study attempting to study this exact issue. The purpose of the study was to determine whether there was any difference in the incidence of PJI in two commonly used bearing couples (metal- on-polyethylene versus ceramic-on-polyethylene).

Based on a retrospective multi-institutional query all patients who received primary THA with MOP or COP bearing surfaces performed during 2005–2009 in two high-volume arthroplasty centers were identified. Demographic factors, comorbidities, length of hospital stay, complications and other relevant information were extracted. PJI was defined based on the MSIS (International Consensus) criteria. Multivariate analysis was performed to determine whether bearing coupling was independently correlated with PJI.

In our data, 25/2,921 (0.9%) patients with MOP and 11/2,643 (0.4%) patients with COP developed PJI. This difference was statistically significant (p=0.01). After the multivariate analysis, controlling for potential confounders (age, body mass index and length of hospital stay, Charlson comorbidity index), MOP bearing surface was found to be an independent factor correlating with higher incidence of PJI (odds ratio: 2.6, 95% confidence interval: 1.02–6.54, p=0.04).

The finding of this study, and others from centers in Europe, suggest that the bearing surface may have an influence on the incidence of PJI. Although, we had originally thought that ceramic bearing surfaces may be used in younger and healthier patients, the multivariate analyses that controlled for all these variables confirms that use of metal femoral head is an independent risk factor for development of PJI. The finding of this study is compelling and begs for future basic science mechanistic investigations.

There is limited evidence in the literature suggesting that ceramic-on-ceramic (CoC) THA is associated with lower risk of revision for prosthetic joint infection (PJI) than other bearing combinations especially metal-on-poly (MoP) and metal-on-metal (MoM). Pitto and Sedel reported hazard ratios of 1.3 – 2.1 for other bearing surfaces versus CoC. Of interest, the PJI rate was not significantly lower in the first 6 months, when most infections occur, but only became significant in the long term. While factors such as patient age, fixation, mode, OR type, use of body exhaust suits, and surgeon volume were considered in the multivariate analysis, BMI, medical comorbidities, and ASA class were not. This is a major weakness that casts doubt on the conclusion, since those three factors are MAJOR risk factors for PJI AND all three factors are more likely to be unevenly distributed, and much more likely present in groups other than CoC. The data was also limited by the fact that it was drawn from a retrospective review of National Registry data, The New Zealand Joint Registry. While similar findings have recently been reported from the Australian Joint Registry, the danger in attributing differences in outcomes to implants alone is possibly the single greatest danger in interpreting registry results. While device design can impact implant survival, other factors such as surgical technique, surgeon, hospital, and especially patient factors have a far greater likelihood of explaining differences in observed results. A recent report from the same New Zealand joint registry reported that obesity, ASA class, surgical approach, and trainee operations all were associated with higher PJI and all would be more likely in non-CoC THAs. Accuracy of diagnosis is also a major concern. Revision for trunnionosis is more common in non-CoC THA and is frequently misdiagnosed as PJI.

Numerous non-registry studies and reviews have compared PJI in CoC vs. other bearings and none have concluded than the incidence of PJI differed significantly.

Aim

Compare clinical outcomes following staged revision arthroplasty for periprosthetic joint infection (PJI) secondary to either multidrug resistant (MDR) bacteria or non-MDR (NMDR) bacteria.

Aim

Dissolvable antibiotic-loaded calcium sulphate beads have been utilized for management of periprosthetic joint infection (PJI) and for aseptic revision arthroplasty. However, wound drainage and toxic reactive synovitis have been substantial problems in prior studies. Currently a commercially pure, physiologic product has been introduced that may reduce complications associated with this treatment modality. We aim to answer the question: does a commercially pure, physiologic version of antibiotic-loaded calcium sulfate beads reduce wound drainage and provide efficacious treatment for PJI and aseptic revision arthroplasty?

Aims. The International Consensus Meeting on Musculoskeletal Infection (ICM, Philadelphia 2018) recommended histology as one of the diagnostic tests although this is not routinely used in a number of UK hospitals. This study aims to explore the role of histology in the diagnosis of infection and whether it is of practical use in those cases where the microbiology samples are either diagnostically unclear or do not correspond to the pre-operative diagnosis or the clinical picture. Patients and Methods. We identified 85 patients who underwent revision knee arthroplasty for either septic or aseptic loosening and for whom both microbiology and histology samples were taken. The procedures were performed by the senior experienced surgeons specialised in revision knee arthroplasty in two centres from Liverpool. Each patient had a minimum of five tissue samples taken, using separate knife and forceps and each sample was divided in half and sent for microbiology and histology in different containers. Fifty-four patients (63.5%) underwent a single-staged revision; ten patients (11.8%) underwent the 1. st. stage of a two staged revision; eleven patients (12.9%) underwent the 2. nd. stage of a two staged revision; one patient (1.2%) underwent an additional revision stage; three patients (3.5%) were treated with a DAIR; three patients (3.5%) had a 2-in-1 revision; two patients (2.4%) had a debridement and polyethylene exchange; and one patient (1.2%) had an arthroscopy biopsy of knee replacement. The cost to process five microbiology samples for each patient was £122.45 on average and for the five histology samples was £130. Results. In 63.5% (n=54) the histology and microbiology confirmed an aseptic joint as suspected beforehand. In 8.2% (n=7) the histology result was the same as the microbiology result confirming infection as suspected beforehand. In 15.3% (n=13) where asepsis was suspected beforehand, one of the five microbiology samples unexpectedly grew an organism but all the histological samples showed no evidence of infection. In these cases, the histology result supported the diagnosis of the likelihood of a contaminant. In 5.9% (n=5) we found differences in the microbiology and histology in one sample and in 7.1% (n=6) the histology was different to the microbiology in more than one sample. Conclusions. In cases where the diagnosis of sepsis within a knee replacement is not in doubt due to pre-operative microbiology, we found no benefit in additional histology sampling. In 28.3% of the cases, the histology was of use in the diagnosis of infection in complex cases and a useful tool in the decision process for further management. In over half of the cases where the revision was for aseptic loosening, the histology result did not alter the management but 28.3% of cases that were thought to be aseptic, microbiology revealed at least one positive sample hence the histology was of use in making a final diagnosis, be that of infection, contamination or to rule out infection. Whilst histology is of use in the latter groups but not the aseptic group, these outcomes are not predictable until after the post-operative period hence histology is required in all these cases. Overall, the histology is a cheap test which is of benefit in the diagnosis of complex peri-prosthetic joint infection in one–third of cases and we support the ICM recommendation

Introduction. Accurate diagnosis of peri-prosthetic joint infection is critical to allow adequate treatment. Currently, the criteria of the Musculo-Skeletal Infection Society (MSIS) serve as a validated reference tool. More recently, these criteria have been modified for better accuracy. The goal of this study was to compare retrospectively the diagnostic accuracy of these two different tools in cases of known peri-prosthetic hip or knee infection or in aseptic cases and to analyze one additional criterion: presence of an early loosening (prior to 2 years after implantation). Material – Methods. All cases of hip or knee prosthesis exchange operated on at our department during the year 2017 have been selected. There were 130 cases in 127 patients: 67 men and 60 women, with a mean age of 69 years − 69 total hip (THA) and 61 total knee (TKA) arthroplasties. 74 cases were septic and 53 cases were aseptic. All criteria included in both classifications were collected: presence of a fistula, results of bacteriological samples, ESR and CRP levels, analysis of the joint fluid, histological analysis. Additionally, the presence of an early loosening was recorded. The diagnosis accuracy of the classical MSIS classification and of the 2018 modification were assessed and compared with a Chi-square test at a 0.05 level of significance. Results. The conventional MSIS classification correctly discriminated between infected and non-infected cases in 128/130 cases (98%). There were two failures by infected cases: one case was considered infected with no major criteria and only three minor criteria; one case was considered infected with no major criteria and only two minor criteria. There was no failure by non-infected cases. The new MSIS classification correctly discriminated between infected and non-infected cases in 129/130 cases (99%). There was one single failure by infected cases: one case was considered infected despite a score of 4 points. There was no significant difference between the diagnostic accuracy of both classifications. The presence of an early loosening had a high specificity (85%) but a low sensitivity (22%). Discussion. The conventional MSIS classification had a high diagnostic accuracy. The new MSIS classification offered only minor, non significant increase of this accuracy. As the new classification involves several additional biological assays, these results might question the cost-effectiveness of the new classification. The presence of an early loosening might be an interesting additional criterion at no additional cost

Introduction. Antibiotic loaded absorbable calcium sulphate beads (ALCSB) are an increasingly popular adjunct in the treatment of musculoskeletal infections including osteomyelitis and peri-prosthetic joint infections (PJI). Limited data exist regarding the clinical indications and biochemical outcomes of ALCSB in PJI cases. Aims. To determine the proportion of organisms that were sensitive to the gentamicin and vancomycin that we add to the ALCSB as a part of our treatment protocol and to determine the prevalence of postoperative hypercalcaemia when used for treatment of hip and knee DAIR (debridement and implant retention) and revision arthroplasty for PJI. Methods. A retrospective review of 160 hip and knee revisions using ALCSB performed between June 2015 and May 2018 at a tertiary unit was performed. 10–40 cc of ALCSB was used for each case containing vancomycin and gentamicin. Data recorded included patient demographics, comorbidities, indication for surgery, operative intervention, microbiological results and serum biochemistry for calcium levels. Results. The cohort consisted of 91 males and 69 females, with a mean age of 69.0 years (21.3 to 93.1) and mean BMI of 34.7(12.6 to 48.1). 56 (35%) had single-stage revision, 45 (28.1%) had first stage revision, 35 (21.9) had DAIR, 19 (11.9%) had second stage revision and 5 (3.1%) other procedures. Organisms included staphylococcus aureus (30.0%), culture-negative (27.5%), staphylococcus epidermidis (18.1%), and pseudomonas aeruginosa (3.1%). 54.3% were sensitive to both vancomycin and gentamicin, 25.0% to vancomycin only and 8.6% to gentamicin only. 11.9% (19/160) of patients had transient post-operative hypercalcaemia (normal range 2.2–2.7mmol/L), peaking at day 6–7 and resolved with hydration by day 10 postoperatively. Preoperatively, 26.9% had albumin <35 g/L and 49.3% had some degree of renal impairment with an eGFR <90 ml/min. Conclusion. The use of ALCSB allows local delivery of vancomycin and gentamicin in lower limb PJI. Organisms were sensitive to this antibiotic combination in 88% cases. Care must be taken to monitor calcium for 10 days post-operatively

Metal Ion Levels Not Useful in Failed M-O-M Hips: Systematic Review; Revision of Failed M-O-M THA at a Tertiary Center; Trunnionosis in Metal-on-Poly THA?; Do Ceramic Heads Eliminate Trunnionosis?; Iliopsoas Impingement After 10 THA; Pain in Young, Active Patients Following THA; Pre-operative Injections Increase Peri-prosthetic THA Infection; Debridement and Implant Retention in THA Infection; THA after Prior Lumbar Spinal Fusion; Lumbar Back Surgery Prior to THA Associated with Worse Outcomes; Raising the Joint Line Causes Mid-Flexion Instability in TKA; No Improvement in Outcomes with Kinematic Alignment in TKA; Botox For TKA Flexion Contracture; Intra-operative Synovitis Predicts Worse Outcomes After TKA for OA; When is it Safe for Patients to Drive After Right TKA?; Alpha-Defensin for Peri-prosthetic Joint Infection; Medial Tibia Overhang and Pain Score After TKA

Aim. The majority of peri-prosthetic joint infection occurring within 1 year of surgery is due to introduction of microbes at the time of surgery. Lavage of total knee replacement leaves a pool of fluid on the surgical drapes. This fluid could be a direct source of wound contamination via suction catheter tip, gloves or instruments. Method. Twenty patients undergoing total knee arthroplasty had a sample of drape fluid sent, after prosthesis implantation, for standard and enrichment culture. The surgery took place in a laminar low theatre with scrub teams in togas. *. and drapes. **. Normal saline was used as the wash. 20ml fluid was taken via syringe and transferred to blood culture bottles in theatre post-operatively. Results. Ten samples (50%) showed bacterial contamination; of these 55% were one organism and 45% polymicrobial. Coagulase negative staphylococcus (CNS) occurred in 90% of positive samples, followed by Moraxella (20%) and MSSA (10%). Organisms grown included skin, nasal, respiratory and environmental pathogens, all but one previously documented as causing septic arthritis. Conclusions. The major contaminant found in our study, CNS, is a skin commensal. This could be from increasing resistance to skin preparations or a decline in theatre etiquette. Fluid collecting in the drapes is a source of potential contamination. All aspects of infection control protocol need continual re-assessment including drape quality, skin and patient preparation and theatre etiquette. Surgeons cannot assume that routine skin preparation and peri-operative antibiotics will eradicate bacterial contamination. It is all our responsibility to implement best infection control practice both in the operating room and through entire patient journey

Aim. Peri-prosthetic joint infection is a serious and expensive complication of joint arthroplasty. Theatre discipline has infection prevention at its core with multiple studies correlating increased door opening with surgical site infection. The WHO, NICE and Philadelphia Consensus all advocate minimal theatre traffic. The Dutch Health Inspectorate consider >5 door openings per procedure excessive. Method. This prospective observational study over five weeks observed theatre door traffic during hip and knee arthroplasty within the eight laminar flow theatres at our institution. Two students attached to the department collected data. Half way through the study notices reminding people not to enter during arthroplasty were placed on the theatre doors. Results. The students observed 59 knees or hip arthroplasty 32 prior to notice's being placed on the theatre doors. The average number of door openings per case was 67 (25–130) prior to intervention and 70 (34–158) after intervention, although opening rates reduced from 1/min to 0.9/min (p=0.053). Reasons for door opening were drawing up medications, blood tests, delivery surgical equipment, general enquiries, staff breaks and “unknown” entries and exits. Conclusions. The rate of door opening was excessive and remained so after reminders were displayed. This deterioration in theatre discipline potentially has a significant negative impact on theatre hygiene and infection control. Individually wrapped components and screws along with the increasing component choice may have played some role in ‘legitimizing’ door opening. It will be challenging to reverse this behavioural trend but must be achieved

Peri-prosthetic joint infection (PJI) can be both a diagnostic and therapeutic challenge in shoulder arthroplasty, due to the indolent nature of the common infecting organisms. Proprionobacterium acnes (P. acnes) is the most common pathogen cultured in revision shoulder arthroplasty. It is a slow growing, anaerobic organism – requires longer incubation period (7–21 days). Coagulase-negative Staphylococcus species (CNSS) is also a common organism responsible for PJI. Established diagnostic tests for hip and knee PJI are often negative in the shoulder despite post-operative growth of intra-operative cultures. Pre-operative synovial aspiration often low volume due to indolent pathogens and successful aspiration is often reported to be 50% or less with Dilisio et al, JBJS 2014: reporting 16.7% sensitivity, 100% specificity. Variable culture length for P. acnes culture protocols are reported from 7–28 days with most groups recommending 14 days. From our research, we demonstrated time to culture growth was significantly shorter in probable true positive culture group (median, 5 vs. 9 days, p=0.002). Frozen section analysis may help intra-operative decision-making (one- vs. two-stage reimplantation) yet the reported sensitivity and specificity in shoulder arthroplasty is far less than in hip and knee arthroplasty. Synovial fluid biomarkers have been identified as part of the innate response to pathogens include pro-inflammatory cytokines and antimicrobial peptides. In a series of prospective studies of revision shoulder arthroplasty, synovial fluid analysis reported by Frangiamore et al, JBJS 2015: IL-6, Frangiamore et al, JSES 2015: α-defensin (Synovasure. TM. ), Frangiamore et al, AAOS 2015: Broader cytokine analysis it was demonstrated that these markers are much more predictive of infection than synovial fluid cultures, frozen section or serum markers

There is no doubt that peri-prosthetic joint infection (PJI) is one the most terrible complications of joint arthroplasty. There has been a surge of interest in PJI in recent years as this problem moves to be the last frontier in joint arthroplasty. There are a number of strategies employed for prevention of PJI. Irrigation of the surgical site with various irrigation solutions is one such strategy as it helps reduce bioburden in the wound and reduce the potential for subsequent infection. Although the irrigation solution may work by dilution phenomenon alone, some believe that bactericidal or bacteriostatic agents may be added to the irrigation solution to increase its efficacy. Addition of antibiotics (Abx) to the irrigation solution stems from the same reasoning. There are a number of serious issues related to the addition of Abx to the irrigation solution or in fact, for pouring into the wound (like the vancomycin powder). Efficacy: There are no randomised prospective studies to demonstrate that addition of Abx to the irrigation solution improves “kill”. To do such a study would be logistically challenging. Basic science studies and other clinical studies with a small number of patients have failed to prove the efficacy of Abx in the irrigation solution. In fact, I would argue that the use of agents like dilute betadine is much more likely to be effective in reduction of bioburden without having many of the issues related to the use of Abx in irrigation solution. Emergence of Resistance: Some may argue what would one lose by adding Abx to the wound or the irrigation solution. The modern society is facing an emerging catastrophe. Antimicrobial Resistance (AMR), if it persists, will kill more people than cancer by the year 2050. Annually 1000s of patients die of ESKAPE or AMR related issues. A recent task force convened by the British government produced a report about AMR which is sobering. The main finding of the task force was that continued liberal use of Abx will lead to further escalation of the AMR crisis that threatens the modern society. The guidelines by the CDC, that are about to be published, will discourage clinicians from pouring Abx into wounds and asks clinicians to exercise Abx stewardship. Expense: There are costs associated with the use of Abx in any circumstance including their addition to irrigation solution. With over 1 million joint arthroplasties being done in the US alone, this cost can be substantial. Hypersensitivity reactions: The use of Abx is not without problems. There have been a few fatalities associated with the use of Abx in patients with recognised and possibly unrecognised hypersensitivity to antibiotics

Aim. Implant-related infections, including peri-prosthetic joint infection (PJI) and infected osteosynthesis, are biofilm-related. Intra-operative diagnosis and pathogen identification is currently considered the diagnostic benchmark; however the presence of bacterial biofilm(s) may have a detrimental effect on pathogen detection with traditional microbiological techniques. Sonication and chemical biofilm debonding have been proposed to overcome, at least partially, this issue, however little is known about their possible economical impact. Aim of this study was to examine direct and indirect hospital costs connected with the routine use of anti-biofilm microbiological techniques applied to hip and knee PJIs. Method. In a first part of the study, the “Turn Around Time (TAT)” and direct costs comparison between a system to find bacteria on removed prosthetic implants. *. , a closed system for intra-operative tissue and implant sampling, transport and anti-biofilm processing, versus sonication has been performed. An additional analysis of the estimated indirect hospital costs, resulting from the diagnostic accuracy of traditional and anti-biofilm microbiological processing has been conducted. Results. Considering an average 5 samples per patient, processed separately with the sonication or pooled together, using the device. *. , the direct costs comparison shows a similar overall average estimated cost per patient when using sonication (€ 400.00) or the system to find bacteria on removed prosthetic implants. *. (€ 391.70). Indirect hospital costs of false positive or negative intra-operative pathogen identification can be estimated as, respectively, € 65,000 and € 90,000, including possible inadequate treatments and/or surgeries and/or need for further hospital stay, risk of infection recurrence/persistence, possible medico-legal claims, etc. Considering 1 out of ten cases of false identification as generating indirect hospital costs (“mitigation factor”: 90%) and an accuracy of current intra-operative microbiological sampling and testing of approximately 80%, it is calculated that any anti-biofilm procedure able to increase the microbiological diagnostic accuracy by 10%, at an average cost per patient of € 500.00, would induce an average hospital cost saving of approximately € 100,000 per 100 treated cases. Conclusions. To our knowledge, this is the first study specifically focused on the potential economical impact of the routine clinical use of microbiological anti-biofilm processing techniques in orthopaedics. The several limitations of this study notwithstanding, including the variable Country-based value of the different direct costs and the assumptions made concerning indirect costs calculations, this analysis points out how more accurate pathogen identification procedures can lead to an improvement of the management of implant-related infections in orthopaedics, with a substantial economical balance

Introduction. The burden of peri-prosthetic joint infection (PJI) following hip and knee surgery is increasing. Endoprosthetic replacement (EPR) is an option for management of massive bone loss resulting from infection around failed lower limb implants. Aims. To determine clinical outcome of EPRs for treatment of PJI around the hip and knee joint. Methods. This was a retrospective consecutive case-series of hip and knee EPRs between 2007–2014 in our tertiary unit for the treatment of PJI following complex arthroplasty or fracture fixation. Data recorded included indication for EPR (infected primary/revision arthroplasty, infected non-union/failed osteosynthesis, gross bone loss following native joint infection), number of previous surgeries, and organism identified. Outcome measures included PJI eradication rate (with failure defined as EPR revision, amputation, or being on life-long suppressive antibiotics), complications, implant survival, mortality, and functional outcome (Oxford Hip/Knee Score; OHS/OKS). Results. 58 EPRs (32 knee and 26 hip) were performed with a mean age of 68 years (range: 35–92). The mean number of previous surgeries prior to EPR was 3.4 (range: 1–10). At mean follow-up of 3.5 years, 11 (19%) patients were deceased. EPR was implanted as a two-stage procedure in 76% of cases. Plastic surgical involvement and flap coverage was necessary in 11 cases. Polymicrobial growth was detected in 40% of cases, followed by Coagulase-negative staphylococci (26%). The overall complication rate was 40%. Recurrence of infection post-EPR occurred in 14 patients (24%); 5 were treated with Debridement, Antibiotics and Implant Retention (DAIR), 3 with revision, 1 with above-knee amputation and the remaining 6 remained on long-term suppressive antibiotics. PJI eradication was achieved in 44 (76%) cases (69% knees and 85% hips). Of the remaining 14 cases, 9 remain on long-term antibiotics. The complication rate was similar in knees (41%) and hips (38%). PJI eradication was more successful in hips (85%) compared to knees (69%). To date, 6 EPRs have been revised (10%). The overall 5-year implant survivorship was 83% (95% CI: 68–98%). The mean OHS was 25 (range 7–39.) and the mean OKS was 20 (range 6–43), the best possible score being 48. Conclusions. This mid-term study provides further support for the use of massive endoprostheses in the eradication of PJI in complex, previously multiply revised cases with subsequent limb salvage (in all but one case). We describe PJI eradication rate of 76% with acceptable functional outcomes. This eradication rate is comparable to that following treatment of PJI associated with standard arthroplasty

Introduction. About 2% of primary total joint replacement arthroplasty (TJA) procedures become infected. Periprosthetic joint infection (PJI) is currently one of the main reasons requiring costly TJA revisions, posing a burden on patients, physicians and insurance companies. 1. Currently used drug-eluting polymers such as bone cements offer limited drug release profiles, sometimes unable to completely clear out bacterial microorganisms within the joint space. For this study we determined the safety and efficacy of an antibiotic-eluting UHMWPE articular surface that delivered local antibiotics at optimal concentrations to treat PJI in a rabbit model. Materials and Methods. Skeletally mature adult male New Zealand White rabbits received either two non-antibiotic eluting UHMWPE (CONTROL, n=5) or vancomycin-eluting UHMWPE (TEST, n=5) (3 mm in diameter and 6 mm length) in the patellofemoral groove (Fig. 1). All rabbits received a beaded titanium rod in the tibial canal (4 mm diameter and 12 mm length). Both groups received two doses of 5 × 10. 7. cfu of bioluminescent S. aureus (Xen 29, PerkinElmer 119240) in 50 µL 0.9 % saline in the following sites: (1) distal tibial canal prior to insertion of the rod; (2) articular space after closure of the joint capsule (Fig. 1). None of the animals received any intravenous antibiotics for this study. Bioluminescence signal (photons/second) was measured when the rabbits expired, or at the study endpoint (day 21). The metal rods were stained with BacLight. ®. Bacterial Live-Dead Stain and imaged using two-photon microscopy to detect live bacteria. Hardware, polyethylene implants and joint tissues were sonicated to further quantify live bacteria via plate seeding. Results. All control rabbits expired within 7 days (Fig. 2a). One rabbit in the test group expired at day 7 and another at day 15. All control rabbits had positive bioluminescence (live bacteria), while none of the test rabbits did (Fig 2b). Kidney (creatinine and BUN) and liver functions (ALT and ALP) remained normal for all rabbits. All control rabbits showed positive bacterial culture after sonication, while all test rabbits were negative. Two-photon imaging showed 75±10 % viability for bacteria adhered to the metal rods in the control and no viability in the test group. Discussion. This rabbit model showed that vancomycin eluted from UHMWPE is sufficient to eradicate S. aureus in joint space and in between the bone-implant interface of tibial canal. One limitation of this study is the lack of intravenous antibiotic treatment, which is standard clinical practice. In addition, joint infections are often associated with already formed biofilms, which were not tested in this study. However, safety data (normal kidney and liver functions) and complete eradication of S. aureus is an encouraging finding. Conclusion. Vancomycin-eluting UHMWPE effectively eliminated bacteria in a rabbit model of acute peri-prosthetic joint infection. This material is promising as a replacement liner to treat joint infections in revision surgery. For any figures or tables, please contact authors directly (see Info & Metrics tab above).

Peri-prosthetic infection remains a leading cause of revision surgery. Recent publications from the American Musculoskeletal Infection Society have sought to establish a definition of peri-prosthetic infection based on clinical findings and laboratory investigations. The limitations of their approach are discussed and an alternative definition is proposed, which it is felt may better reflect the uncertainties encountered in clinical practice.