Aim

There is limited data on the frequency and impact of untoward events such as glove perforation, contamination of the surgical field (drape perforation, laceration, detachment), the unsterile object in the surgical field (hair, sweat droplet…), defecation, elevated air temperature…that may happen in the operating theatre. These events should influence the surgical site infection rate but it is not clear to what extent. We wanted to calculate the frequency and measure the impact of these events on the infection and general revision rate.

Periprosthetic joint infections (PJI) continue to be a diagnostic challenge for orthopedic surgeons. Chronic PJI are sometimes difficult to diagnose and occasionally present in a subclinical fashion with normal CRP/ESR and/or normal joint aspiration. Some institutions advocate for routine use of intraoperative culture swabs at the time of all revision surgeries to definitively rule out infection. The purpose of this study is to determine whether routine intraoperative cultures is an appropriate and cost effective method of diagnosing subclinical chronic PJI in revision joint replacement patients with a low clinical suspicion for infection. We performed a retrospective chart review and identified 33 patients that underwent revision hip or knee replacement from a single surgeon over a five-month period. The AAOS guidelines for preoperative PJI workup were followed. 13 patients were diagnosed preoperatively with infection and excluded from the study. 20 patients underwent revision joint replacement and three separate cultures swabs were taken for each patient to help in determining true-positive cultures. Infectious Disease was consulted for all patients with any positive culture. Culture results were reviewed. At our hospital, the cost billed to insurance for a single culture is $1,458.58. We did not calculate the cost of the consultant fee. Three (15%) of the 20 revision arthroplasty patients had a single positive culture. Infectious Disease consultants diagnosed all three of these positive cultures as contaminants. None of the patients had a true-positive intraoperative culture. The total cost billed by the hospital to obtain these cultures in all 20 patients was $87,514.80. In our study, obtaining a set of three intraoperative cultures for those patients with a negative preoperative infection workup was not only cost prohibitive but did not diagnose a single subclinical infection. Studies to find other more reliable, accurate, and cost effective alternatives to diagnose PJI are warranted. In patients undergoing revision hip or knee arthroplasty with a low preoperative clinical suspicion for infection, it does not seem that routine intraoperative culture swabs are necessary or cost effective method for diagnosing subclinical periprosthetic joint infection

Aim

”There is not a lot of data of the frequency and impact of unwanted events including glove perforation, contamination of the surgical field (drape perforation, laceration, detachment, bone bounced back from an unsterile object), unsterile object in the surgical field (hair, sweat droplet…), defecation, elevated air temperature, and others. Mishaps occur in every surgical theatre. These events should influence the surgical site infection rate but it is not clear to what extent. We wanted to calculate the frequency and measure the impact of these events on the infection and revision rate of the relative patients.”

With an ageing population and an increasing number of primary arthroplasties performed, the revision burden is predicted to increase. The aims of this study were to 1. Determine the revision burden in an academic hospital over a 11-year period; 2. identify the direct hospital cost associated with the delivery of revision service and 3. ascertain factors associated with increased cost. This is an IRB-approved, retrospective, single tertiary referral center, consecutive case series. Using the hospital data warehouse, all patients that underwent revision hip or knee arthroplasty surgery between 2008-2018 were identified. 1632 revisions were identified (1304 patients), consisting of 1061 hip and 571 knee revisions. The majority of revisions were performed for mechanical-related problems and aseptic loosening (n=903; 55.3%); followed by periprosthetic joint infection (n=553; 33.9%) and periprosthetic fractures (176; 10.8%). Cost and length of stay was determined for all patient. The direct in-hospital costs were converted to 2020 inflation-adjusted Canadian dollars. Several patients- (age; gender; HOMR- and ASA-scores; Hemoglobin level) and surgical- (indication for surgery; surgical site) factors were tested for possible associations. The number of revisions increased by 210% in the study period (2008 vs. 2018: 83 vs. 174). Revision indications changed over study period; with prevalence of fracture increasing by 460% (5 in 2008 vs. 23 in 2018) with an accompanying reduction in mechanical-related reasons, whilst revisions for infection remained constant. The mean annual cost over the entire study period was 3.9 MMCAD (range:2.4–5.1 MMCAD). The cost raised 150% over the study period from 2.4 MMCAD in 2008 to 3.6 MMCAD. Revisions for fractured had the greatest length of stay, the highest mean age, HOMR-score, ASA and cost associated with treatment compared to other revision indications (p < 0 .001). Patient factors associated with cost and length of stay included ASA- and HOMR-scores, Charlson-Comorbidity score and age. The revision burden increased 1.5-fold over the years and so has the direct cost of care delivery. The increased cost is primarily related to the prolonged hospital stay and increased surgical cost. For tertiary care units, these findings indicate a need to identify strategies on improving efficiencies whilst improving the quality of patient care (e.g. efficient ways of reducing acute hospital stay) and reducing the raise of the economic burden on a publicly funded health system

Introduction

A proportion of patients with hip and knee prosthetic joint infection (PJI) undergo multiple revisions with the aim of eradicating infection and improving quality of life. The aim of this study was to describe the microbiology cultured from multiply revised hip and knee replacement procedures to guide antimicrobial therapy at the time of surgery.

Aim. The prevalence of unexpected positive cultures (UPC) in aseptic revision surgery of the joint with a prior septic revision procedure in the same joint remain unknown. The purpose of this study was to determine the prevalence of UPC in aseptic revisions performed in patients with a previous septic revision in the same joint. As secondary outcome measure, we explore possible risk factors associated with UPC and the re-revision rates. Method. This retrospective single-center study includes all patients between January 2016 and October 2018 with an aseptic revision total hip or knee arthroplasty procedure with a prior septic revision in the same joint. Patients with less than three microbiology samples, without joint aspiration or with aseptic revision surgery performed <3 weeks after a septic revision were excluded. UPC was defined as a single positive culture in a revision that the surgeon had classified as aseptic according to the 2018 International Consensus Meeting. Results. A total of 139 revision total hip/knee arthroplasties in patients with a previous septic revision were performed during the study period. After excluding 47 cases with insufficient information, a total of 92 patients were recruited for final analysis. The patient cohort consist of 52 males and 40 females with a mean age of 70 years (±10.6). There were 66 (71.7%) hips and 26 (28.3%) knees. The mean time between the septic and the aseptic revision was 83 months (±89). The two main causes for the aseptic revision were aseptic loosening (n=57, 62%) followed by instability (n=21, 22.9%). We identified 11 (12%) UPC in the entire cohort, while in 3 cases there was a concordance of the germ compared to the previous septic surgery. There were no differences for the presence of UPC between hips and knees (p=0.282), diabetes (p=0.701), immunosuppression (p= 0.252), previous one-stage or two-stages septic revision (p=0.316), or between the causes for the aseptic revision ((p=0.429). There was no correlation between the UPC and time after the septic revision (p=0.773). Conclusions. The prevalence of UPC in this specific group was similar to those reported in the literature for aseptic revisons. More studies, regarding this patient group are necessitated to better understand and more securely interprete the results in those high-risk aseptic revisions

Aim. The diagnosis of periprosthetic joint infection (PJI) remains a clinical dilemma, since presentations of PJI usually greatly overlap with aseptic failure (AF). The aim of this study is to evaluate the values of plasma fibrinogen, individually or in combination with CRP, ESR and WBC, for distinguishing PJI from AF. Method. We retrospectively enrolled 357 cases who underwent revision hip or knee arthroplasties in the Third Affiliated Hospital of Southern Medical University, Sun Yat-sen Memorial Hospital and the First Affiliated Hospital of Sun Yat-sen University from January 2013 to December 2021, including 197 AF, 116 PJI and 44 reimplantation. The diagnostic capacity of preoperative fibrinogen, CRP, ESR and WBC as well as their combinations for differentiating PJI from AF were assessed by ROC curves. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy were calculated according to the optimal cutoff value based on the Youden index. All biomarkers were further investigated for their potential ability to predict optimal timing of reimplantation as well as their diagnostic capacity in the subgroups of the knee and hip PJI. Furthermore, the correlations among fibrinogen, CRP and ESR in the patients with PJI and AF were analyzed to further evaluate the potential capacity of fibrinogen in the diagnosis of PJI. Results. The levels of fibrinogen, CRP, ESR and WBC were significantly higher in PJI group than in AF group. ROC analyses showed that the AUCs of fibrinogen, CRP, ESR and WBC were 0.879, 0.903, 0.879 and 0.685, respectively. The optimal threshold of fibrinogen is 4.04 g/L (74.1% sensitivity, 85.6% specificity, 76.1% PPV, 85.0% NPV and 81.8% accuracy). Combining fibrinogen with CRP and/or ESR (AUC: 0.903∼0.914) yielded almost equivalent diagnostic efficiency compared with the combination of CRP and ESR (AUC: 0.910). Besides, fibrinogen yielded AUCs of 0.869 (cutoff: 3.44 g/L) and 0.887 (cutoff: 4.12 g/L) in the hip and knee subgroups, with higher specificity and PPV of 93.1% and 96.1% in the knee PJI. Intriguingly, as for the cases with CRP < 10mg/L and ESR ≧ 30 mm/h, the specificity and NPV of fibrinogen for diagnosing PJI were 92.2% and 83.9%. Conclusions. Plasma fibrinogen is considered as a potential first-line screening marker for PJI detection and timing of reimplantation. As for the patients with an increased ESR but normal CRP, a low fibrinogen level (below 4.04 g/L) is more likely to rule out PJI

Aims. Elective orthopaedic services have had to adapt to significant system-wide pressures since the emergence of COVID-19 in December 2019. Length of stay is often recognized as a key marker of quality of care in patients undergoing arthroplasty. Expeditious discharge is key in establishing early rehabilitation and in reducing infection risk, both procedure-related and from COVID-19. The primary aim was to determine the effects of the COVID-19 pandemic length of stay following hip and knee arthroplasty at a high-volume, elective orthopaedic centre. Methods. A retrospective cohort study was performed. Patients undergoing primary or revision hip or knee arthroplasty over a six-month period, from 1 July to 31 December 2020, were compared to the same period in 2019 before the COVID-19 pandemic. Demographic data, American Society of Anesthesiologists (ASA) grade, wait to surgery, COVID-19 status, and length of hospital stay were recorded. Results. A total of 1,311 patients underwent hip or knee arthroplasty in the six-month period following recommencement of elective services in 2020 compared to 1,527 patients the year before. Waiting time to surgery increased in post-COVID-19 group (137 days vs 78; p < 0.001). Length of stay also significantly increased (0.49 days; p < 0.001) despite no difference in age or ASA grade. There were no cases of postoperative COVID-19 infection. Conclusion. Time to surgery and length of hospital stay were significantly higher following recommencement of elective orthopaedic services in the latter part of 2020 in comparison to a similar patient cohort from the year before. Longer waiting times may have contributed to the clinical and radiological deterioration of arthritis and general musculoskeletal conditioning, which may in turn have affected immediate postoperative rehabilitation and mobilization, as well as increasing hospital stay. Cite this article: Bone Jt Open 2021;2(8):655–660

Aim. Aim was to compare revision rates when using single versus dual antibiotic loaded cement (ABLC) in hip fracture arthroplasty and aseptic revision hip or knee arthroplasty using data from the Dutch national joint registry (LROI). Methods. All primary cemented (hemi-)arthroplasties for acute hip fractures and cemented aseptic hip or knee revision arthroplasties, were incorporated in 3 datasets. All registered implants between 2007 and 2018 were included (minimum 2 years follow-up). Primary end-point was subsequent revision rates for infection and for any reason in the single and dual ABLC groups. Cumulative crude incidence of revision was calculated using competing risk analysis. Results. A total of 22,308 hip fracture arthroplasties, 2,529 hip revision and 7,124 knee revision arthroplasties were registered and analyzed in the study period. The majority of hip fracture patients (97.1%) was treated with single ABLC. For hip and knee revision arthroplasties dual ABLC was used in 33.8% and 25.7%. The revision rate for infection in the fracture arthroplasty group was not different between groups (0.5% versus 0.8%, p=0.27). The re-revision rate following hip or knee revision based on single versus dual ABLC was not different between groups (3.2% versus 2.8%, p=0.82 for hip revision and 1.8% versus 2.5%, p=0.36 for knee revision). In addition, the re-revision rate for any reason was not different in all three datasets. The crude cumulative revision and re-revision rates for any reason based on single ABLC versus dual ABLC showed no differences in all three datasets. The crude cumulative 7-year re-revision rate for any reason following revision THA with Gentamicin ABLC use was 11.8%, with Gentamicin + Clindamycin ABLC use 13.1% and with Erythromycin + Colistin ABLC use 14.8% (ns). The crude cumulative 9-year re-revision rate for any reason following revision TKA with Gentamicin ABLC use was 17.7% and with Gentamicin + Clindamycin ABLC use 16.5% (ns). Conclusions. In conclusion, we could not show a difference in revision rate for hip fracture arthroplasty or re-revision rates for revision hip- or knee arthroplasty with the use of dual ABLC compared to single ABLC bone cement, with 7and 9 year follow up. The low percentage of dual ABLC in hip fracture arthroplasties in our registry do not enable us to make a reliable estimation of the added value in this patient category. The results of this study do not confirm the potential benefit of dual ABLC use in revision cases

Aims. As the peak of the COVID-19 pandemic passes, the challenge shifts to safe resumption of routine medical services, including elective orthopaedic surgery. Protocols including pre-operative self-isolation, COVID-19 testing, and surgery at a non-COVID-19 site have been developed to minimize risk of transmission. Despite this, it is likely that many patients will want to delay surgery for fear of contracting COVID-19. The aim of this study is to identify the number of patients who still want to proceed with planned elective orthopaedic surgery in this current environment. Methods. This is a prospective, single surgeon study of 102 patients who were on the waiting list for an elective hip or knee procedure during the COVID-19 pandemic. Baseline characteristics including age, ASA grade, COVID-19 risk, procedure type, surgical priority, and admission type were recorded. The primary outcome was patient consent to continue with planned surgical care after resumption of elective orthopaedic services. Subgroup analysis was also performed to determine if any specific patient factors influenced the decision to proceed with surgery. Results. Overall, 58 patients (56.8%) wanted to continue with planned surgical care at the earliest possibility. Patients classified as ASA I and ASA II were more likely to agree to surgery (60.5% and 60.0%, respectively) compared to ASA III and ASA IV patients (44.4% and 0.0%, respectively) (p = 0.01). In addition, patients undergoing soft tissue knee surgery were more likely to consent to surgery (90.0%) compared to patients undergoing primary hip arthroplasty (68.6%), primary knee arthroplasty (48.7%), revision hip or knee arthroplasty (0.0%), or hip and knee injections (43.8%) (p = 0.03). Conclusion. Restarting elective orthopaedic services during the COVID-19 pandemic remains a significant challenge. Given the uncertain environment, it is unsurprising that only 56% of patients were prepared to continue with their planned surgical care upon resumption of elective services. Cite this article: Bone Joint Open 2020;1-6:267–271

INTRODUCTION. In the United States, the Centers for Medicare and Medicaid Services consider rates of unplanned hospital readmissions to be indicators of provider quality. Understanding the common reasons for readmission following total joint arthroplasty will allow for improved standards of care and better outcomes for patients. The current study seeks to evaluate the rates, reasons, and Medicare costs for readmission after total hip and total knee arthroplasty. METHODS. This study used the Limited Data Set (LDS) from the Centers for Medicare and Medicaid Services (CMS) to identify all primary, elective Total Knee Arthroplasties (TKA) and Total Hip Arthroplasties (THA) performed from January 2013 through June 2016. The data were limited to Diagnosis-Related Group (DRG) 470, which is comprised of major joint replacements without major complications or comorbidities. Readmissions were classified by corresponding DRG. Readmission rates, causes, and associated Medicare Part A payments were aggregated over a ninety-day post-discharge period for 804,448 TKA and 409,844 THA. RESULTS. There were 31,172 readmissions in the ninety days following THA, for a readmission rate of 7.6%. There were 51,768 readmissions following TKA, for a readmission rate of 6.4%. The leading causes of readmission post-THA were revision of hip or knee replacement (17.66%); septicemia (4.76%); and postoperative infections (3.74%). The most common reasons for readmission post-TKA were postoperative infections (6.42%); septicemia (4.84%); and esophagitis (3.85%). In contrast to THA, implant revisions only accounted for 2.51% of readmissions after TKA. The mean cost of readmission post-THA was $11,682, while the mean cost of readmission post-TKA was $8,955. DISCUSSION AND CONCLUSION. Ninety-day readmission rates for both THA and TKA remained stable for the duration of the study period, suggesting the need for additional research on the efficacy of various programs intended to reduce the incidence of readmission

Background. Recent reports demonstrate that Next Generation Sequencing (NGS) facilitates pathogen identification in the context of culture-negative PJI; however the clinical relevance of the polymicrobial genomic signal often generated remains unknown. This study was conceived to explore: (1) the ability of NGS to identify pathogens in culture-negative PJI; and (2) determine whether organisms detected by NGS, as part of a prospective observational study, had any role in later failure of patients undergoing surgical treatment for PJI. Methods. In this prospective study samples were collected in 238 consecutive patients undergoing revision total hip and knee arthroplasties. Of these 83 patients (34.9%) had PJI, as determined using the Musculoskeletal Infection Society (MSIS) criteria, and of these 20 were culture-negative (CN-PJI). Synovial fluid, deep tissue and swabs were obtained at the time of surgery and sent for NGS and culture/MALDI-TOF. Patients undergoing reimplantation were excluded. Treatment failure was assessed using the previously described Delphi criteria. In cases of re-operation, organisms present were confirmed by culture and MALDI-TOF. Concordance of the infecting pathogen(s) at failure with the NGS analysis at the initial stage CN- PJI procedure was determined. Results. Twenty cases of culture-negative PJI were identified (Figure 1). CNPJI rate in our samples was 24%. NGS was positive in 18 cases. Two cases were both culture and NGS negative. Eight CN-PJIs (8/20; 40%) failed by re-operation with infection recurrence confirmed on culture. In 7 of these 8 cases (88%), the organism at failure was present on NGS at the time of the initial CN-PJI procedure. The remaining case failed with a new organism, via likely hematogenous seeding from an inter-current infection (Figure 2). NGS detected several organisms in CN-PJI cases (Figure 3). Discussion. CN-PJI is often associated with polymicrobial genomic organism profile. Furthermore, most of the failures by infection recurrence were due to an organism previously detected by NGS. Our findings suggest some cases of PJI may be polymicrobial and escape detection using conventional culture. Further multi-institutional work with larger numbers and longer clinical follow-up is required for validation

Aim. Synovial fluid investigation is the best alternative to diagnose prosthetic joint infection (PJI) before adequate microbiological/histology sampling during revision surgery. Although accurate preoperative diagnosis is certainly recommended, puncturing every patient before revision arthroplasty raises concerns about safety and feasibility issues especially in difficult to access joint (e.g., hip), that often require OR time and fluoroscopy/ultrasound guidance. Currently there is no clear guidelines regarding optimal indications to perform preoperative joint aspiration to diagnose PJI before revision surgery. The main goal of this study is to determine the accuracy of our institutional criteria using the new European Bone and Joint Infection Society (EBJIS) PJI definition. Method. We retrospectively evaluated every single- or first-stage for presumed aseptic or known infected revision total hip/knee arthroplasty procedures between 2013–2020. Preoperative clinical and laboratory features were systematically scrutinized. Cases with insufficient information for accurate final PJI diagnosis (i.e., no perioperative synovial fluid examination or no multiple cultures including sonication of removed implant) were excluded. Preoperative joint aspiration is recommended in our institution if any of the following criteria are met: 1) elevated CRP and/or ESR; 2) early failure (<2 years) or repeat failure; 3) high clinical suspicion/risk factors are present. Performance of such criteria were compared against final postoperative EBJIS definition PJI diagnosis. Results. A total of 364 revision THAs or TKAs were performed during the study period. After excluding 258 cases with insufficient information, a total of 106 patients were ultimately included. 38 (35,8 %) were classified as confirmed infections, 10 (9.4 %) as likely infected and 58 (54.7%) as infection unlikely. Of those, 37 confirmed infection cases, 9 likely infected cases and 32 infection unlikely cases did have indication for preoperative synovial fluid collection before revision surgery. Institutional criteria showed 95.8 % Sensitivity, 44.83 % Specificity, 92.9 % Negative Predictive Value (NPV) and 59 % Positive Predictive Value (PPV). Conclusions. Sensitivity and NPV of the aforementioned institutional criteria are very high even with the use of the more sensitive EBJIS PJI definition. As such they seem to be a valid alternative in selecting patients that should be punctured before revision arthroplasty. They identify the vast majority of infected patients while saving a significant number of patients from unnecessary procedures

Aim. Infection remains among the first reasons of failure of joint prosthesis. According to various preclinical reports, antibacterial coatings of implants may prevent bacterial adhesion and biofilm formation. Aim of this study is to present the first clinical trial on an antibiotic-loaded fast-resorbable hydrogel coating. *. , in patients undergoing hip or knee prosthesis. Method. In this multi-center, randomized, prospective, study, a total of 380 patients, scheduled to undergo primary or revision total hip or knee joint replacement, using a cementless or a hybrid implant, were randomly assigned, in six European orthopedic centers, to receive the antibiotic-loaded DAC coating or to a control group, without coating. Pre- and post-operative assessment of clinical scores, wound healing, laboratory tests and x-ray were performed at fixed time intervals. Results. Overall 373 patients were available at a minimum follow-up of 6 months (maximum 24 months). On average, wound healing, laboratory tests and radiographic findings did not show any significant difference between the two-groups. Eleven early surgical site infections (6%) were observed in the control group, compared to one (0.6%) in the treated group (p=0.003). No local or systemic side effects related to DAC hydrogel coating were observed and no detectable interference with implant osteointegration was noted. Conclusions. The use of a fast-resorbable, antibiotic-loaded hydrogel implant coating provides a reduced rate of early surgical site infections after hip or knee joint replacement using cementless or hybrid implants, without any detectable adverse event or side effects

Background. Intravenous and topical tranexamic acid (TXA) has become increasingly popular in total joint arthroplasty to decrease perioperative blood loss. In direct comparison, the outcomes and risks of either modality have been found to be equivalent. In addition, current literature has also demonstrated that topical TXA is safe and effective in the healthy population. To our knowledge, there is a scarcity of studies demonstrating the safety of topical TXA in high risk patient populations undergoing total joint arthroplasty or revision joint arthroplasty. The purpose of this study is to determine the safety of topical TXA in patients undergoing total or revision arthroplasty that are also on chronic anticoagulant or anti-platelet therapy. Methods. We performeded a retrospective review of patients undergoing primary and revision total hip or knee arthroplasties that received topical TXA (3g/100mL NS) from November 2012 to March 2015. All patients, regardless of co-morbidities, were included in the study population. Patients were divided into 3 groups:. Group 1: Patients without any antiplatelet or anticoagulant therapy within 90 days of surgery. Group 2: Patients receiving antiplatelet therapy (Aspirin and/or Plavix) within 90 days of surgery. Group 3: Patients receiving anti-coagulant therapy within 90 days of surgery (low molecular weight heparin, unfractionated heparin, warfarin, dabigatran, rivaroxaban, apixaban). Chart review analyzing ICD-9 and ICD-10 coding was then utilized to establish any peri-operative complications within the 30 day post-operative period in all groups. Complications amongst the groups were evaluated via chi-squared testing as well as multivariate linear regression. Review of current literature and CMS protocols were used to establish reportable peri-operative complications. Wound infections, thromboembolic events and vascular complications such as myocardial infarction, pulmonary embolism, deep venous thrombosis, stroke, aortic dissection were included. Results. During the study period, a total 1471 total joint arthroplasties were performed on 1324 patients (88.7% knee arthroplasty, 11.3% hip arthroplasty). Group 1 included 1033 patients who were not on any prior anti-platelet or anticoagulant therapy. Group 2 included 254 patients receiving chronic antiplatelet therapy 90 days prior to surgery. Group 3 included 184 patients receiving chronic anticoagulant therapy 90 days prior to surgery. No statistically significant differences were found between the groups for any of the included peri-operative complications. The most common complication occurring amongst all the groups was superficial wound infection, which occurred in a total of 60 (4.1%) patients in contrast to 18 (1.2%) patients who sustained an acute deep peri-prosthetic infection. Twenty (1.4%) patients sustained an ultrasound proven deep vein thrombosis, with the highest prevalence occurring in those patients receiving no anticoagulation prior to surgery (15/20, 75%), however this was not statistically significant following linear regression analysis. Conclusions. To our knowledge, this is the first study that demonstrates that topical tranexamic acid is safe to use in so-called high risk patients who are being treated prior to surgery with anti-platelet or anti-coagulation therapy

Background. In 2012, the National Joint Registry recorded 86,488 primary total hip replacements (THR) and 9,678 revisions (1). To date aseptic loosening remains the most common cause of revision in hip and knee arthroplasty, accounting for 40% and 32% of all cases respectively and emphasising the need to optimise osseointegration in order to reduce revisions. Clinically, osseointegration results in asymptomatic stable durable fixation of orthopaedic implants. Osseointegration is a complex process involving a number of distinct mechanisms affected by the implant surface topography, which is defined by surface orientation and surface roughness. Micro- and nano-topography levels have discrete effects on implant osseointegration and yet the role on cell function and subsequent bone implant function is unknown. Nanotopography such as collagen banding is a critical component influencing the SSC niche in vivo and has been shown to influence a range of cell behaviours in vitro (2,3). We have used unique fabricated nanotopographical pillar substrates to examine the function of human bone stem cells on titanium surfaces. Aim. To investigate the effect of nanotopographical cues on adult skeletal stem cell (SSC) fate, phenotype and function within in-vitro environments. Materials and methods. Adult human skeleltal stem cells (SSCs) were immunoselected and enriched using STRO-1 antibody and cultured on tissue culture plastic (TCP) and titanium-coated nanotopgraphical substrates (illustrated in Figure 1). Following culture, metabolic activity of SSCs on TCP and Ti substrates was compared. Subsequently, osteoinductive potential was analysed under basal and osteogenic conditions (four groups: TCP in basal media, TCP in osteogenic media, Ti planar substrates basal and Ti pillar substrates basal). Results. At 7 days, cell metabolic activity was significantly enhanced on Ti substrates, specifically on Ti pillars of defined height in comparison to TCP (Figure 2). Following culture on defined topographies for 21 days, expression of the bone matrix protein, osteopontin, on Ti pillars was significantly enhanced when compared to TCP or Ti planar (Figure 3). Conclusion. We demonstrate the ability of discrete raised nanopillars to modualte adult SSC populations in the absence of any chemical cues. These results indicate the potential of discrete and defined nanopillar constructs to stimulate SSC function, an effect not observed on planar Ti constructs. These findings herald exciting opportunities to improve the bioactivity of implant design and, ultimately, osseointegration with clinical implications therein

Background:. Until recently, there has been no consensus of the best approach to dIfferentiating aseptic from septic loosening in joint replacement patients. The recent AAOS Clinical Practice Guideline Summary that was published in 2010, tasks orthopedic surgeons with the strong recommendation of obtaining ESR and CRP for all patients needing hip and knee arthroplasty revision surgery and aspirating the joint based upon these results. The purpose of this study is to determine from our patients whether this guideline has been helpful and cost effective in determining periprosthetic joint infections. Methods:. We retrospectively reviewed charts of 50 consecutive patients who underwent revision total hip or knee arthroplasty. Each patient received an ESR and CRP level prior to operation and patients with known periprosthetic joint infections were excluded from the study. As guidelines recommend, aspiration with cultures and cell count were obtained on all knees with either elevated ESR or CRP and all hips with both ESR and CRP elevated. We then determined how many patients needing revision arthroplasty of the hip or knee benefited from ESR, CRP, and aspiration by finding subclinical periprosthetic infection and changing the intraoperative treatment. Hospital charge data was used to report cost of this protocol. Results. Sixty-four percent (32/50) patients had elevated ESR and/or CRP. Eighteen patients (12 hips; 7 knees) required joint aspirations per the guidelines. None of the aspirations were positive for bacterial growth. The total hospital charges for aspiration and cultures in this patient population were $81, 712.44. No sub clinical infection was identified. Conclusion:. Although guidelines may more readily diagnose every case of subclinical joint infection, we must continue to evaluate the cost of this type protocol in a busy revision practice

Aim. C-reactive protein(CRP) and erythrocyte sedimentation rate(ESR) are non-specific markers with variable reported accuracy in the diagnosis of prosthetic joint infection(PJI). They are often used as a part of the initial diagnostics as they are widely available and inexpensive. Given its high false-negative rate, CRP is an insufficient screening tool for PJI especially in low virulence microorganisms. Nevertheless, many advocate ESR offers no added advantage and is useless in this setting. Our goal is to determine if the combined measurement of ESR and CRP offers increased sensitivity for the preliminary screening of PJI over isolated CRP measurement. Method. We retrospectively evaluated every single- or first-stage for presumed aseptic or known infected revision total hip/knee arthroplasty procedures between 2013–2018. Cases without preoperative CRP and ESR measurement as well those without synovial fluid for differential leukocyte count and/or no multiple cultures including sonication of removed implant obtained during surgery were excluded. Diagnostic accuracy was compared against two different PJI definitions: 2013 International Consensus Meeting and ProImplant Foundation definitions. Results. A total of 398 revision were performed during the study period. After excluding 293 cases with insufficient information, a total of 105 patients were studied. Naturally, CRP and ESR mean values were significantly higher among PJI cases compared to aseptic cases. When compared against 2013 International Consensus Meeting definition, CPR has a sensibility 86.5% (45/52) that increases to 94.2% (49/52) with the combined measurement (ESR and CRP). The sensitivity also increased when compared against the ProImplant Foundation definition (72.6% (45/62) vs 85.5% (53/62)). Conclusions. After the inciting insult, CRP raises and drops rapidly and ESR response is slower but also much more enduring. One can only hypothesize that chronic PJI runs perhaps a fluctuating inflammatory course that can sometimes be more accurately picked up by ESR and not CRP measurement. Our results seem to corroborate that ESR measurement is a valid adjunct to isolated CRP measurement in the initial screening of PJI in painful total joint arthroplasties

Introduction. The intra-operative diagnosis of Prosthetic Joint Infection (PJI) is a dilemma requiring intra-operative sampling of suspicious tissues for frozen section, deep tissue culture and histopathology to secure a diagnosis. Alfa defensin-1 testing has been introduced as a quick and reliable test for confirming or ruling out PJI. This study aims to assess its intra-operative reliability compared to the standard tests. Methods. Twenty patients who underwent revision hip and knee arthroplasty surgery were included. Patients joint aspirate was tested intra-operatively with the Synovasure kit, which takes approximately ten minutes for a result. Our standard protocol of collecting 5 deep tissue samples for culture and one sample for histopathology was followed. Results for Alfa defensin-1 test were then compared with final culture and histopathology results in all these patients. Results. Our results show an excellent correlation with the final deep tissue cultures and histopathology outcomes. Literature reports frozen section to have low (58–73%) sensitivity but high (96%) specificity. Conclusions. Alfa defensin-1 test is easy, quick and efficient; results were available immediately intra-operatively. Cryosection is time consuming with samples shipped to the reference laboratory at times resulting in intra-operative delays. In our practice Alfa defensin-1 test certainly will replace frozen section for intra-operative testing

Our Trust's prophylactic antibiotic regime for elective hip and knee replacements recently changed, following the publication of Department of Health guidelines aimed at reducing the incidence of Clostridium Difficile associated diarrhoea (CDAD). We aimed to assess whether this change has reduced the incidence of post-operative CDAD. We reviewed all primary and revision total hip and knee replacements performed in Gloucestershire Royal Hospital between April 2007 and March 2010. Up to August 2008, patients received prophylaxis with cefuroxime (Group A). This subsequently changed to flucloxacillin and gentamicin (Group B). All patients who developed CDAD within one month of surgery were identified and their case-notes were reviewed for the presence of CDAD risk factors, such as concomitant use of broad-spectrum antibiotics. 3117 patients were included and 15 developed CDAD (0.48%); 12 patients (0.77%) from Group A and 3 from Group B (0.19%), representing a four-fold decrease. Analysis of a 2×2 contingency table with Fisher's exact test showed that the difference between the two groups was statistically significant (P=0.0347). Case-note analysis revealed that 8/12 patients in Group A and 1/3 patients in Group B had other risk factors for developing CDAD. Excluding these patients, the difference between the two groups was not statistically significant (P=0.218). CDAD is exceedingly rare following total joint replacement surgery, especially when the only antibiotics given are prophylactic. Our figures are in line with a general decline in CDAD nationally from 2007. This decline is most likely due to multiple factors, such as hand-washing, barrier nursing and restrictive antibiotic policies. The effect of the change in prophylaxis is therefore difficult to quantify. Choice of prophylactic antibiotics should be based upon their efficacy alone, not their potential to reduce CDAD