Aims. Prophylactic antibiotic regimens for elective primary total hip and knee arthroplasty vary widely across hospitals and trusts in the UK. This study aimed to identify antibiotic prophylaxis regimens currently in use for elective primary arthroplasty across the UK, establish variations in antibiotic prophylaxis regimens and their impact on the risk of periprosthetic joint infection (PJI) in the first-year post-index procedure, and evaluate adherence to current international consensus guidance. Methods. The guidelines for the primary and alternative recommended prophylactic antibiotic regimens in clean orthopaedic surgery (primary arthroplasty) for 109 hospitals and trusts across the UK were sought by searching each trust and hospital’s website (intranet webpages), and by using the MicroGuide app. The mean cost of each antibiotic regimen was calculated using price data from the British National Formulary (BNF). Regimens were then compared to the 2018 Philadelphia Consensus Guidance, to evaluate adherence to international guidance. Results. The primary choice and dosing of the prophylactic antimicrobial regimens varied widely. The two most used regimens were combined teicoplanin and gentamicin, and cefuroxime followed by two or three doses of cefuroxime eight-hourly, recommended by 24 centres (22.02%) each. The alternative choice and dosing of the prophylactic antimicrobial regimen also varied widely across the 83 centres with data available. Prophylaxis regimens across some centres fail to cover the likeliest causes of surgical site infection (SSI). Five centres (4.59%) recommend co-amoxiclav, which confers no Staphylococcus coverage, while 33 centres (30.28%) recommend cefuroxime, which confers no Enterococcus coverage. Limited adherence to 2018 Philadelphia Consensus Guidance was observed, with 67 centres (61.50%) not including a cephalosporin in their guidance. Conclusion. This analysis of guidance on antimicrobial prophylaxis in primary arthroplasty across 109 hospitals and trusts in the UK has identified widespread variation in primary and alternative antimicrobial regimens currently recommended. Cite this article: Bone Jt Open 2023;4(10):742–749

From 1992 to 1999, 713 total joint arthroplasties were performed in The Department of Orthopaedic Surgery, The University of Hong Kong. Since January 1993, a uniform prophylactic antibiotic regime was employed: one dose of first generation cephalosporin (one gram cephazonlin) on induction and every 4-hourly. In case of sequential bilateral total knee arthroplasty, one gram of cephazolin will be given on induction for the first knee and one hour before the operation on the opposite knee. Antibiotic will be discontinued post-operatively. No significant difference was identified between the infection rate before (1.4%) and after (1.2%) the adoption of the prophylactic antibiotic guidelines (p > 0.4). The study had shown that one dose of first generation cephalosporin is as effective as multiple dose of prophylactic antibiotic, either first or second generation cephalosporin, in preventing infection in total joint arthroplasty

Objectives. We wanted to investigate regional variations in the organisms reported to be causing peri-prosthetic infections and to report on prophylaxis regimens currently in use across England. Methods. Analysis of data routinely collected by Public Health England’s (PHE) national surgical site infection database on elective primary hip and knee arthroplasty procedures between April 2010 and March 2013 to investigate regional variations in causative organisms. A separate national survey of 145 hospital Trusts (groups of hospitals under local management) in England routinely performing primary hip and/or knee arthroplasty was carried out by standard email questionnaire. Results. Analysis of 189 858 elective primary hip and knee arthroplasty procedures and 1116 surgical site infections found statistically significant variations for some causative organism between regions. There was a 100% response rate to the prophylaxis questionnaire that showed substantial variation between individual trust guidelines. A number of regimens currently in use are inconsistent with the best available evidence. Conclusions. The approach towards antibiotic prophylaxis in elective arthroplasty nationwide reveals substantial variation without clear justification. Only seven causative organisms are responsible for 89% of infections affecting primary hip and knee arthroplasty, which cannot justify such widespread variation between prophylactic antibiotic policies. Cite this article: Bone Joint Res 2015;4:181–189

C. Difficile infections in elderly patients with hip fractures is associated with high morbidity and mortality. Antibiotic regimens with penicillin and its derivatives is a leading cause. Antibiotic prophylactic preferences vary across different hospitals within NHS. We compared two antibiotic prophylactic regimens - Cefuroxime only prophylaxis and Teicoplanin with Gentamicin prophylaxis in fracture neck of femur surgery, and evaluated the incidence of C. Difficile diarrhea and Surgical Site Infection (SSI). To assess the Surgical Site Infection and C. Difficile infection rate associated with different regimens of antibiotics prophylaxis in fracture neck of femur surgery. Data was analyzed retrospectively. Neck of femur fracture patients treated surgically from 2009 in our unit were included. Age, gender, co morbidities, type of fracture, operation, ASA grade was collected. 1242 patients received Cefuroxime only prophylaxis between January 2009 and December 2012 (Group 1) and 486 patients received Teicoplanin with Gentamicin between October 2015 and March 2017 (Group 2). There were 353 males and 889 female patients in Group 1 and 138 males and 348 female patients in Group 2. The co morbidities in both groups were comparable. Incidence of C. Difficile diarrhea and Surgical Site Infection (SSI) was noted. Statistical analysis with chi square test was performed to determine the ‘p’ value. C. Diff diarrhea rate in Group 2 was 0.41 % as compared to 1.29 % in Group 1. The Surgical Site Infection (SSI) rate in Group 2 was 0.41 % as compared to 3.06 % in Group 1. The comparative results were statistically significant (p = 0.0009). Prophylactic antibiotic regimen of Teicoplanin with Gentamicin showed significant reduction in C. Difficile diarrhea & Surgical Site Infection in fracture neck of femur patients undergoing surgery

Objective

Clinical studies of patients with bone sarcomas have been challenged by insufficient numbers at individual centres to draw valid conclusions. Our objective was to assess the feasibility of conducting a definitive multi-centre randomised controlled trial (RCT) to determine whether a five-day regimen of post-operative antibiotics, in comparison to a 24-hour regimen, decreases surgical site infections in patients undergoing endoprosthetic reconstruction for lower extremity primary bone tumours.

Aims. Antibiotic prophylaxis involving timely administration of appropriately dosed antibiotic is considered effective to reduce the risk of surgical site infection (SSI) after total hip and total knee arthroplasty (THA/TKA). Cephalosporins provide effective prophylaxis, although evidence regarding the optimal timing and dosage of prophylactic antibiotics is inconclusive. The aim of this study is to examine the association between cephalosporin prophylaxis dose, timing, and duration, and the risk of SSI after THA/TKA. Methods. A prospective multicentre cohort study was undertaken in consenting adults with osteoarthritis undergoing elective primary TKA/THA at one of 19 high-volume Australian public/private hospitals. Data were collected prior to and for one-year post surgery. Logistic regression was undertaken to explore associations between dose, timing, and duration of cephalosporin prophylaxis and SSI. Data were analyzed for 1,838 participants. There were 264 SSI comprising 63 deep SSI (defined as requiring intravenous antibiotics, readmission, or reoperation) and 161 superficial SSI (defined as requiring oral antibiotics) experienced by 249 (13.6%) participants within 365 days of surgery. Results. In adjusted modelling, factors associated with a significant reduction in any SSI and deep SSI included: correct weight-adjusted dose (any SSI; adjusted odds ratio (aOR) 0.68 (95% confidence interval (CI) 0.47 to 0.99); p = 0.045); commencing preoperative cephalosporin within 60 minutes (any SSI, aOR 0.56 (95% CI 0.36 to 0.89); p = 0.012; deep SSI, aOR 0.29 (95% CI 0.15 to 0.59); p < 0.001) or 60 minutes or longer prior to skin incision (aOR 0.35 (95% CI 0.17 to 0.70); p = 0.004; deep SSI, AOR 0.27 (95% CI 0.09 to 0.83); p = 0.022), compared to at or after skin incision. Other factors significantly associated with an increased risk of any SSI, but not deep SSI alone, were receiving a non-cephalosporin antibiotic preoperatively (aOR 1.35 (95% CI 1.01 to 1.81); p = 0.044) and changing cephalosporin dose (aOR 1.76 (95% CI 1.22 to 2.57); p = 0.002). There was no difference in risk of any or deep SSI between the duration of prophylaxis less than or in excess of 24 hours. Conclusion. Ensuring adequate, weight-adjusted dosing and early, preoperative delivery of prophylactic antibiotics may reduce the risk of SSI in THA/TKA, whereas the duration of prophylaxis beyond 24 hours is unnecessary. Cite this article: Bone Jt Open 2022;3(3):252–260

Infection is still a major problem in implant surgery. Most infections are caused by bacteria that enter the wound at the time of the operation. Although prophylactic antibiotics given intravenously have been shown to be effective if given during the correct time frame, the concentration of local antibiotics in the knee in response to intravenous antibiotics is about 1/3 that achieved in the serum, and the level is transient. The concentration of antibiotics in the joint fluid achieved with antibiotics applied locally during surgery is 1000 times higher, and can be maintained throughout the procedure. High concentration persists in drainage fluid for 24 hours after surgery. Studies done with use of local antibiotics in spinal implant surgery indicate a major reduction in the rate of infection, and costs analysis shows a remarkable monetary benefit to this effect. Local antibiotic irrigation during implant surgery is inexpensive, easy, and effective

Infection is still a major problem in implant surgery. Most infections are caused by bacteria that enter the wound at the time of the operation. Although prophylactic antibiotics given intravenously have been shown to be effective if given during the correct time frame, the concentration of local antibiotics in the knee in response to intravenous antibiotics is about 1/3 that achieved in the serum, and the level is transient. The concentration of antibiotics in the joint fluid achieved with antibiotics applied locally during surgery is 1000 times higher, and can be maintained throughout the procedure. High concentration persists in drainage fluid for 24 hours after surgery. Studies done with use of local antibiotics in spinal implant surgery indicate a major reduction in the rate of infection, and costs analysis shows a remarkable monetary benefit to this effect. Local antibiotic irrigation during implant surgery is inexpensive, easy, and effective

In primary total knee arthroplasty (TKA) performed under ischemia the antibiotic prophylaxis is administered 15’ before inflating the tourniquet. The infection rate in TKA is higher than in hip arthroplasty. We hypothesise that ischemia could impair the efficacy of the antibiotic. The objective of our study was to compare the effectiveness of two schedules of antibiotic administration.

We conducted a randomised and a double blind study. Patients were assigned to receive placebo 15’ before inflating tourniquet and cefuroxim 1.5 g 10’ before releasing the tourniquet (experimental arm) or cefuroxim 1.5 g 15’ before inflating tourniquet and placebo 15’ before releasing tourniquet (standard arm). In both arms cefuroxime 1.5 g was administered 6 hours after finishing surgery. The variables gathered were: age, sex, indication for TKA, co-morbidity, ASA score, duration of the operation, number of blood transfusions, days of hospitalisation and number of surgical site infections after 3 months of surgery. Categorical variables were compared using the χ² test or the Fisher exact test and quantitative variables using Student-t test.

Nine hundred and eight patients were randomised and 466 and 442 patients were allocated to experimental and standard arms respectively. Both groups were similar and there were no differences in deep and superficial infection rates, 1.39% and 4.18% for experimental arm and 3.39% and 3.17% for standard arm (p> 0.05). The experimental arm had a lower global and deep infection rate than the standard arm when the length of surgery was lower than the 75th percentile (global: 4.03 vs 7.93%, p=0.04, deep: 1.72% vs 4.44%, p=0.07).

The administration of antibiotic prophylaxis 10’ before releasing the tourniquet decreases the surgical site infection rate when the duration of surgery is lower than the 75th percentile.

Our study sought to establish the necessity of prolonged pre-operative antibiotic prophylaxis in patients presenting with zone II and zone V acute flexor tendon injuries (FTI). We hypothesized that a single dose of prophylactic antibiotic was adequate in prevention of post-operative wound infection in acute zone II and V FTI. This was a prospective study of 116 patients who presented with zone II and zone V acute FTI. The study included patients who were 18 years and older. Those with macroscopic contamination, immunocompromised, open fractures, bite injuries, and crush injuries were excluded. Patients were randomised into a group receiving a single dose of prophylactic antibiotic and another group receiving a continuous 8 hourly antibiotic doses until the day of surgery. Each group was subdivided into occupational and non-occupational injuries. Their post-operative wound outcomes were documented 10 – 14 days after surgery. The wound outcome was reported as no infection, superficial infection (treated with wound dressings), and deep infection (requiring surgical debridement). There was 0.9% rate of deep post-operative wound infections, which was a single zone V acute FTI case in a single dose prophylactic antibiotic group. There was a 7.8% superficial post-operative wound infection rate, which was mainly zone II acute FTI in both antibiotic groups. There was a strong association between zone II acute FTI and post-operative wound infection (p < 0.05). There was no association between (antibiotic dosage or place of injury) with post-operative wound infection (p > 0.05). There is no benefit in prescribing prolonged pre-operative antibiotic in patients with acute, simple lacerations to zone II and zone V FTI if there is no macroscopic wound contamination

Aim. One of the most severe complications of primary total knee arthroplasty (TKA) is periprosthetic joint infection (PJI). Nowadays, the use of antibiotic-loaded cement for prevention of infection is still controversial. The aim of the present study is to evaluate the use of an antibiotic-loaded cement to reduce the infection rate in primary total knee arthroplasty. Method. Prospective randomized study, with 2893 cemented total knee arthroplasties performed between 2005 and 2010 in our institution. Two different groups were formed depending on which bone cement was used, without antibiotic (the control group) or loaded with erythromycin and colistin (the study group). All patients received the same systemic prophylactic antibiotics. The patients were followed for a minimum of twelve months. The rate of infection was analyzed according to the criteria of the Centers for Disease Control and Prevention (CDC). Results. In 1452 patients the prosthetic components were fixed using bone cement without antibiotic and in 1441 patients bone cement loaded with erythromycin and colistin was used. There were no differences between both groups in terms of demographic data (age, sex and BMI), either in operating time (p>0,05). The rate of infection was similar in both groups, being 2,0% (n=29) in the control group and 1,7% in the study group (p=0,58) at 8,7 years (SD 5,1) of follow up. In terms of prosthetic revision due to any cause (infected or aseptic), there wasn't differences between groups, performing a total of 61 revision arthroplasties in control group and 68 in study group (p>0,05). Moreover, we analyzed the erythromycin resistance rate, being no differences between both groups (p=0.6). Conclusions. The use of erythromycin and colistin-loaded bone cement in total knee arthroplasty did not lead to a decrease in the rate of infection when systemic prophylactic antibiotics were used, a finding that suggests that its use would not be indicated in the general population

Introduction: The role of prophylactic antibiotics in reducing the incidence of infection following hip and knee arthroplasty is well established. The British Orthopaedic Association (BOA) published best practice guidance on the use of prophylactic antibiotics in hip and knee arthroplasty. The guidance stated that all patients should receive prophylactic antibiotics at induction of anaesthesia and that each unit should have a locally agreed policy with advice from microbiologist. The aim of this audit was to compare the practice in our unit with the BOA guidance and implement necessary changes. Patients and Methods: A prospective audit was conducted over a one month period in 2007 and included all patients undergoing elective primary hip and knee replacements. A similar re-audit was conducted over one month period in 2008 after the initial audit recommendations were implemented. Results: Forty patients (40) were included in the initial audit. All patients received prophylactic antibiotics at induction but the choice, dose and duration of administration of antibiotics varied widely among surgeons in the unit. After discussion with the local microbiologist, we recommended a departmental policy for prophylactic antibiotics. The policy recommended a single dose of Cefuroxime and Gentamycin for standard cases and a single dose of Teicoplanin and Gentamycin for high-MRSA risk cases. A re-audit was conducted after the new policy was agreed. The re-audit included 33 patients. All patients received prophylactic antibiotics at induction. The choice of antibiotics was concordant with the policy in 79% of cases and duration of administration was appropriate in 85% of cases. Overall, the policy was adhered to in 22 cases (67 %). Discussion & Conclusions: The closed audit cycle resulted in improvement of our practice but the compliance rate with the new policy was lower than expected. Although it is the primary responsibility of the operating surgeon to ensure the appropriate prophylactic antibiotics are administered, more awareness of other team members is necessary to improve the compliance rate with the new policy

Introduction: Hallux valgus corrective surgery is frequently performed, often with the administration of prophylactic antibiotics, although opinion is divided as to whether these antibiotics confer any benefit with little being published on the subject. The few papers that have been published suggest that there is no difference in infection rates, with the overall rate 1–2%. Furthermore, the increasing incidence of multi-resistant bacteria is a concern to all. The Scottish Health Executive has identified the rationalisation of antibiotic prescribing as one of the principal means of reducing the development of these organisms. Materials and Methods: All patients undergoing hallux valgus surgery via a first metatarsal osteotomy were included, excluding repeat surgery to the same foot. The operation performed, the use of prophylactic antibiotics and the incidence of postoperative infection were all prospectively recorded. Infection was defined using the Scottish Surgical Site Infection Surveillance criteria. In addition, Orthopaedic Consultants in the west of Scotland were contacted asking whether they use antibiotics in hallux valgus surgery and what their perception of infection risk was. Results: The study is currently ongoing. Currently, we have completed data for 64 patients (43 with prophylactic antibiotics, 21 without). Two patients developed a post operative infection both of whom had received prophylactic antibiotics. Thirty-five consultants replied, of which 15 regularly performed surgery for hallux valgus. Prophylactic antibiotics were used by seven, with the average perception of infection risk 4%. Discussion: The current results appear to support the literature in suggesting there is no difference in the incidence of infection between those receiving prophylactic antibiotics and those not. We aim to continue this study, aiming for over 100 patients. Conclusion: Antibiotic prophylaxis during hallux valgus surgery does not appear to lower the risk of postoperative infection, with the overall risk of infection lower than what is generally perceived

Aim. Megaprosthesis have become a standard option in limb preserving surgery after bone resection in musculoskeletal tumors. Recently they have also been used in complex revision arthroplasty in cases with massive bone loss. The aim of this study was to analyze the incidence of periprosthetic joint infection (PJI) both in primary oncology cases and aseptic revision cases and analyze which are the significant risk factors for PJI with a special interest on the use of prophylactic antibiotic loaded calcium sulfate beads. Method. All patients undergoing surgery with the use of megaprosthesis in our institution between January/2012 and December/2022 were retrospectively reviewed. Data was collected from electronic medical records. We identified 108 procedures involving megaprosthesis in 90 patients with an average follow-up of 37 months. Indications were 79 primary musculoskeletal tumors and 29 aseptic complex revision arthroplasty. Results. Table 1 shows relevant clinical information. No significant risk factor was found either in uni or multivariate analysis. PJI rate was 15% (12/79) for primary musculoskeletal surgery and 31% (9/29) for complex revision surgery. The use of antibiotic loaded calcium sulfate beads did not show an advantage – 22% (9/41) with vs. 18% (12/67) without. Conclusions. In this relatively small series it was not possible to show a significal association between PJI and certain known risk factors such as gender, ASA score, site of surgery (knee) and revision surgery. The use of antibiotic loaded calcium sulfate beads as prophylaxis was not beneficial in reducing PJI rates in our cohort. We acknowledge the limitations of our study: a small sample group, in a single institution with heterogeneity in terms of diagnosis and surgical site. We recognize the need for a multicentric study with a larger cohort to validate these findings. For any tables or figures, please contact the authors directly

Functional outcomes are important for patients with bone tumors undergoing lower extremity endoprosthetic reconstruction; however, there is limited empirical evidence evaluating function longitudinally. The objective of this study was to determine the changes in function over time in patients undergoing endoprosthetic reconstructions of the proximal femur, distal femur and proximal tibia. We conducted a secondary analysis of functional outcome data from the Prophylactic Antibiotic Regimens in Tumor Surgery (PARITY) trial. Patient function was assessed with the Musculoskeletal Tumor Society Score 93 (MSTS) and the Toronto Extremity Salvage Score (TESS), which were administered preoperatively and at 3, 6 and 12 months postoperatively. Both instruments are scored from 0-100, with higher scores indicated greater function. Mean functional scores were evaluated over time and we explored for differences among patients undergoing proximal femur reconstructions (PFR), distal femur reconstructions (DFR) and proximal tibia reconstructions (PTR). The patient-importance of statistically significant differences in function was evaluated utilizing the minimally important difference (MID) of 12 for the MSTS and 11 for the TESS. We explored for differences in change scores between each time interval with paired t-tests. Differences based on endoprosthetic reconstruction undertaken were evaluated by analysis of variance and post-hoc comparisons using the Tukey test. A total of 573 patients were included. The overall mean MSTS and TESS scores were 77.1(SD±21) and 80.2(SD±20) respectively at 1-year post-surgery, demonstrating approximately a 20-point improvement from baseline for both instruments. When evaluating change scores over time by type of reconstruction, PFR patients experienced significant functional improvement during the 3-6 and 6-12 month follow-up intervals, DFR patients demonstrated significant improvements in function at each follow-up interval, and PTR patients reported a significant decrease in function from baseline to 3 months, and subsequent improvements during the 3-6 and 6-12 month intervals. On average, patients undergoing endoprosthetic reconstruction of the lower extremity experience important improvements in function from baseline within the first year. Patterns of functional recovery varied significantly based on type of reconstruction performed. The results of this study will inform both clinicians and patients about the expected rehabilitation course and functional outcomes following endoprosthetic reconstruction of the lower extremity

Laminar flow theatres were first introduced in the United Kingdom in the 1960s and 1970s and have become standard in orthopaedic surgery involving implants. A study from 1982 showed a 50% reduction in infections with joint arthroplasties when compared to conventional theatres and laminar flow became standard in the following decades. Recent evidence including a meta-analysis from 2017 questions the effectiveness of these theatre systems. Most of the evidence for Laminar flow use is based on arthroplasty surgery. We aimed to determine the effect of using non-laminar flow theatres on our trauma patients. A total of 1809 patients who had trauma surgery were identified from 2019 to 2021. 917 patients were operated on in a laminar theatre and 892 in a non-laminar theatre across two operating sites. We identified the surgical site infections as reported through our surveillance program within the first 90 days of infection. Patient co-morbidities were noted through patient records and procedure length was also noted. Of the 1809 trauma patients identified between the years of 2019 and 2021, 917 patients had operations in a laminar flow theatre and 892 in a non-laminar theatre. Of the 892 operated in non-laminar flow theatres, 543 were operated in the University Hospital of Wales (UHW) and 349 at the University Hospital of Llandough (UHL). An analysis of soft tissue infections and hospital acquired infections post-operatively demonstrated 15/543 and 71/543 respectively for non-laminar UHW infections and 4/349 and 21/349 for non-laminar UHL infections. A look at laminar flow patients showed 25/917 with soft tissue infections and 86/917 hospital acquired infections. There was no difference between laminar and non-laminar flow theatre infection rates showing rates of 12.1% and 12.2% respectively. In our trauma patients we noticed no significant advantage of using laminar flow theatres when compared to non-laminar flow theatres. This is in keeping with some recently published literature. Laminar flow theatres have been shown to decrease airborne pathogen counts under controlled conditions, but we conclude in the day to day environment of trauma theatres these conditions are either not met or that the theoretical advantage of laminar flow does not translate to a direct advantage of reduction of infections which may be achieved by standard prophylactic antibiotics

Purpose: Prophylactic antibiotics are frequently withheld until cultures are obtained in revision TKA. A prospective study was undertaken to determine whether prophylactic pre-operative IV antibiotics would affect the results of cultures obtained intra-operatively. Method: A consecutive series of 25 TKA’s with a known infecting organism were enrolled over 36 months. Inclusion criteria: clinically infected TKA, a known preoperative infecting organism, and no recent antibiotic therapy. Re-aspiration of the infected TKA was performed following anesthesia and sterile prep. IV antibiotic prophylaxis was then administered and the tourniquet was then inflated. Intra-operative culture swabs and tissue were obtained at arthrotomy. The timing of events was recorded. Pre/post antibiotic culture data were analyzed to determine the effect of IV preoperative prophylactic antibiotics on cultures obtained intra-operatively. Results: Mean time from end of antibiotic infusion to tourniquet inflation was 15 minutes; to arthrotomy culture was 25 minutes. In all 25 knees the organism(s) cultured at arthrotomy were the same as obtained at pre-operative aspiration. In 24 knees the organism cultured was sensitive to the preoperative prophylactic antibiotics given (Ancef and Vancomycin); one patient grew Candida albicans. Conclusion: Pre-operative prophylactic antibiotics did not affect the results of intra-operative cultures, and should not be withheld prior to infected TKA surgery when an organism has been identified on aspiration. Based on these results, holding pre-operative antibiotics prior to revision TKA is rarely justified

Aim. Deadspace is the tissue and bony defect in a surgical wound after closure. This space is presumably poorly perfused favouring bacterial proliferation and biofilm formation. In arthroplasty surgery, an obligate deadspace surrounding the prosthesis is introduced and deadspace management, in combination with obtaining therapeutic prophylactic antibiotic concentrations, is important for limiting the risk of acquiring a periprosthetic joint infection (PJI). This study aimed to investigate cefuroxime distribution to an orthopaedic surgical deadspace in comparison with plasma and bone concentrations during two dosing intervals (8 h × 2). Method. In a setup imitating shoulder arthroplasty surgery, but without insertion of a prosthesis, microdialysis catheters were placed for cefuroxime sampling in a deadspace in the glenohumeral joint and in cancellous bone of the scapular neck in eighteen pigs. Blood samples were collected from a central venous catheter as a reference. Cefuroxime was administered according to weight (20 mg/kg). The primary endpoint was time above the cefuroxime minimal inhibitory concentration of the free fraction of cefuroxime for Staphylococcus aureus (fT > MIC (4 µg/mL)). Results. During the two dosing intervals, mean fT > MIC (4 µg/mL) was significantly longer in deadspace (605 min) compared with plasma (284 min) and bone (334 min). For deadspace, the mean time to reach 4 µg/mL was prolonged from the first dosing interval (8 min) to the second dosing interval (21 min), while the peak drug concentration was lower and half-life was longer in the second dosing interval. Conclusions. In conclusion, weight-adjusted cefuroxime fT > MIC (4 µg/mL) and elimination from the deadspace was longer in comparison to plasma and bone. Our results suggest a deadspace consolidation and a longer diffusions distance, resulting in a low cefuroxime turn-over. Based on theoretical targets, cefuroxime appears to be an appropriate prophylactic drug for the prevention of PJI. Acknowledgments. We would like to thank Department of Clinical Medicine, the surgical research laboratories, Aarhus University Hospital and Department of Clinical Biochemistry, Lillebaelt Hospital, Vejle, Denmark, for supporting this study. This research was funded by Novo Nordisk Foundation, grant number [NNF20OC0062032, 2020]

Aim. Antimicrobial resistance (AMR) aggravates an already difficult treatment of periprosthetic joint infections (PJI). The prevalence of drug-resistant pathogens varies across countries and increases over time. Regular monitoring of bacteriological analyses should be performed. Due to many factors influencing the AMR, the correct choice of antimicrobial management remains arguable. The primary purpose of this retrospective study was to identify and compare causative bacteria and to compare the incidence of antibiotic resistance between the septic revision total knee arthroplasty (TKA) and septic revision total hip arthroplasty (THA). Method. A review of all revision TKAs and revision THAs, undertaken between 2007 and 2020 in a tertiary referral centre, was performed. Included were cases meeting the consensus criteria for PJI, in which an organism has been identified. There were no major differences in tissue sampling between revision TKAs and revision THAs over time. Results. A total of 228 bacterial strains, isolated after revision TKA and THA, were analysed for their resistance to 20 different antibiotics. There was a statistically significant higher occurrence of Gram-negative bacteria (p=0.002) and Enterococcus species (p=0.026) identified after revision THAs compared to TKA. The comparison of antibiotic resistance between revision TKAs and revision THAs was statistically significant in 9 of 20 analysed antibiotics. Pathogens isolated after revision THA were much more resistant compared to pathogens isolated after revision TKA. Resistance in revision THAs was significantly higher to oxacillin (p=0.03), ciprofloxacin (p<0.001), levofloxacin (p<0.001), moxifloxacin (p=0.005), clindamycin (p<0.001), co-trimoxazole (p<0.001), imipenem (p=0.01), rifampicin (p=0.005) and tetracycline (p=0.009). There was no significantly higher resistance of pathogens isolated after revision TKAs detected. No statistically significant difference in antibiotic resistance of Gram-negative bacteria between revision TKA and revision THA was observed. Conclusions. The occurrence and the resistance of bacteria to antibiotics differs significantly between revision TKAs and revision THAs. This has implications on of the choice of empirical antibiotic in revision surgery as well as prophylactic antibiotic in primary surgery, depending on the joint that is to be replaced