Aims. The purpose of this study was to compare the clinical outcomes, mortalities, implant survival rates, and complications of total knee arthroplasty (TKA) in patients with or without hepatitis B virus (HBV) infection over at least ten years of follow-up. Methods. From January 2008 to December 2010, 266 TKAs were performed in 169 patients with HBV (HBV group). A total of 169 propensity score–matched patients without HBV were chosen for the control group in a one-to-one ratio. Then, the clinical outcomes, mortalities, implant survival rates, and complications of TKA in the two groups were compared. The mean follow-up periods were 11.7 years (10.5 to 13.4) in the HBV group and 11.8 years (11.5 to 12.4) in the control group. Results. The mean Knee Society scores in the HBV and control groups improved from 37.1 (SD 5.6) and 38.4 (SD 5.4) points preoperatively to 78.1 (SD 10.8) and 81.7 (SD 10.2) points at final follow-up (p = 0.314), while the mean function scores in the HBV and control groups improved from 36.2 and 37.3 points preoperatively to 77.8 and 83.2 points at final follow-up (p = 0.137). Nine knees in the HBV group required revision surgery, including seven due to septic loosening and two due to aseptic loosening. Four knees in the control group required revision surgery, including three due to septic loosening and one due to aseptic loosening. Kaplan–Meier survivorship analysis with the revision of either component as an endpoint in the HBV and control groups estimated 96.6% and 98.5% chances of survival for ten years, respectively (p = 0.160). Conclusion. TKA in patients with HBV infection resulted in good clinical outcomes and survivorship. However, there was a higher revision rate over a minimum ten-year follow-up period compared to TKA in patients without HBV infection. Cite this article: Bone Jt Open 2022;3(6):470–474

Aims. In cases of severe periprosthetic joint infection (PJI) of the knee, salvage procedures such as knee arthrodesis (KA) or above-knee amputation (AKA) must be considered. As both treatments result in limitations in quality of life (QoL), we aimed to compare outcomes and factors influencing complication rates, mortality, and mobility. Methods. Patients with PJI of the knee and subsequent KA or AKA between June 2011 and May 2021 were included. Demographic data, comorbidities, and patient history were analyzed. Functional outcomes and QoL were prospectively assessed in both groups with additional treatment-specific scores after AKA. Outcomes, complications, and mortality were evaluated. Results. A total of 98 patients were included, 52 treated with arthrodesis and 47 with AKA. The mean number of revision surgeries between primary arthroplasty and arthrodesis or AKA was 7.85 (SD 5.39). Mean follow-up was 77.7 months (SD 30.9), with a minimum follow-up of two years. Complications requiring further revision surgery occurred in 11.5% of patients after arthrodesis and in 37.0% of AKA patients. Positive intraoperative tissue cultures obtained during AKA was significantly associated with the risk of further surgical revision. Two-year mortality rate of arthrodesis was significantly lower compared to AKA (3.8% vs 28.3%), with age as an independent risk factor in the AKA group. Functional outcomes and QoL were better after arthrodesis compared to AKA. Neuropathic pain was reported by 19 patients after AKA, and only 45.7% of patients were fitted or were intended to be fitted with a prosthesis. One-year infection-free survival after arthrodesis was 88.5%, compared to 78.5% after AKA. Conclusion. Above-knee amputation in PJI results in high complication and mortality rates and poorer functional outcome compared to arthrodesis. Mortality rates after AKA depend on patient age and mobility, with most patients not able to be fitted with a prosthesis. Therefore, arthrodesis should be preferred whenever possible if salvage procedures are indicated. Cite this article: Bone Joint J 2024;106-B(7):669–679

Aims. Despite recent literature questioning their use, vancomycin and clindamycin often substitute cefazolin as the preoperative antibiotic prophylaxis in primary total knee arthroplasty (TKA), especially in the setting of documented allergy to penicillin. Topical povidone-iodine lavage and vancomycin powder (VIP) are adjuncts that may further broaden antimicrobial coverage, and have shown some promise in recent investigations. The purpose of this study, therefore, is to compare the risk of acute periprosthetic joint infection (PJI) in primary TKA patients who received cefazolin and VIP to those who received a non-cephalosporin alternative and VIP. Methods. This was a retrospective cohort study of 11,550 primary TKAs performed at an orthopaedic hospital between 2013 and 2019. The primary outcome was PJI occurring within 90 days of surgery. Patients were stratified into two groups (cefazolin vs non-cephalosporin) based on their preoperative antibiotic. All patients also received the VIP protocol at wound closure. Bivariate and multiple logistic regression analyses were performed to control for potential confounders and identify the odds ratio of PJI. Results. In all, 10,484 knees (90.8%) received cefazolin, while 1,066 knees (9.2%) received a non-cephalosporin agent (either vancomycin or clindamycin) as preoperative prophylaxis. The rate of PJI in the cefazolin group (0.5%; 48/10,484) was significantly lower than the rate of PJI in the non-cephalosporin group (1.0%; 11/1,066) (p = 0.012). After controlling for confounding variables, the odds ratio (OR) of developing a PJI was increased in the non-cephalosporin cohort compared to the cefazolin cohort (OR 2.389; 1.2 to 4.6); p = 0.01). Conclusion. Despite the use of topical irrigant solutions and addition of local antimicrobial agents, the use of a non-cephalosporin perioperative antibiotic continues to be associated with a greater risk of TKA PJI compared to cefazolin. Strategies that increase the proportion of patients receiving cefazolin rather than non-cephalosporin alternatives must be emphasized. Cite this article: Bone Jt Open 2022;3(1):35–41

Aims. Periprosthetic joint infection (PJI) is a challenging complication of any arthroplasty procedure. We reviewed our use of static antibiotic-loaded cement spacers (ABLCSs) for staged management of PJI where segmental bone loss, ligamentous instability, or soft-tissue defects necessitate a static construct. We reviewed factors contributing to their failure and techniques to avoid these complications when using ABLCSs in this context. Methods. A retrospective analysis was conducted of 94 patients undergoing first-stage revision of an infected knee prosthesis between September 2007 and January 2020 at a single institution. Radiographs and clinical records were used to assess and classify the incidence and causes of static spacer failure. Of the 94 cases, there were 19 primary total knee arthroplasties (TKAs), ten revision TKAs (varus-valgus constraint), 20 hinged TKAs, one arthrodesis (nail), one failed spacer (performed elsewhere), 21 distal femoral endoprosthetic arthroplasties, and 22 proximal tibial arthroplasties. Results. A total of 35/94 patients (37.2%) had spacer-related complications, of which 26/35 complications (74.3%) were because of mechanical failure of the spacer construct, while 9/35 (25.7%) were due to recurrence of infection. Risk factors for internal failure were a construct where the total intramedullary spacer length was less than twice the length of the central osseous defect (p = 0.009), where proximal or distal intraosseous spacer contact was < 10%, and after tibial tubercle osteotomy (p = 0.005). The incidence of spacer complications significantly increased the time to second stage: mean 157 days (42 to 458) in those without complications versus 227 days (11 to 528) with complications (p = 0.014). Conclusion. The failure rate of static antibiotic-loaded cement spacers is much higher than anticipated. Complications of the spacer significantly increased the time to second-stage revision. The risk of mechanical failure is significantly increased if the spacer is less than double the size of the segmental defect, or if inadequate reinforcement is inserted into the residual bone. These findings serve as a guide for surgeons to avoid mechanical complications with static spacers. Cite this article: Bone Joint J 2024;106-B(10):1067–1073

Aims. This study aims to identify the top unanswered research priorities in the field of knee surgery using consensus-based methodology. Methods. Initial research questions were generated using an online survey sent to all 680 members of the British Association for Surgery of the Knee (BASK). Duplicates were removed and a longlist was generated from this scoping exercise by a panel of 13 experts from across the UK who provided oversight of the process. A modified Delphi process was used to refine the questions and determine a final list. To rank the final list of questions, each question was scored between one (low importance) and ten (high importance) in order to produce the final list. Results. This consensus exercise took place between December 2020 and April 2022. A total of 286 clinicians from the BASK membership provided input for the initial scoping exercise, which generated a list of 105 distinct research questions. Following review and prioritization, a longlist of 51 questions was sent out for two rounds of the Delphi process. A total of 42 clinicians responded to the first round and 24 responded to the second round. A final list of 24 research questions was then ranked by 36 clinicians. The topics included arthroplasty, infection, meniscus, osteotomy, patellofemoral, cartilage, and ligament pathologies. The management of early osteoarthritis was the highest-ranking question. Conclusion. A Delphi exercise involving the BASK membership has identified the future research priorities in knee surgery. This list of questions will allow clinicians, researchers, and funders to collaborate in order to deliver high-quality research in knee surgery and further advance the care provided to patients with knee pathology. Cite this article: Bone Joint J 2024;106-B(7):662–668

Aims. The diagnosis of periprosthetic joint infection (PJI) can be challenging as the symptoms are similar to other conditions, and the markers used for diagnosis have limited sensitivity and specificity. Recent research has suggested using blood cell ratios, such as platelet-to-volume ratio (PVR) and platelet-to-lymphocyte ratio (PLR), to improve diagnostic accuracy. The aim of the study was to further validate the effectiveness of PVR and PLR in diagnosing PJI. Methods. A retrospective review was conducted to assess the accuracy of different marker combinations for diagnosing chronic PJI. A total of 573 patients were included in the study, of which 124 knees and 122 hips had a diagnosis of chronic PJI. Complete blood count and synovial fluid analysis were collected. Recently published blood cell ratio cut-off points were applied to receiver operating characteristic curves for all markers and combinations. The area under the curve (AUC), sensitivity, specificity, and positive and negative predictive values were calculated. Results. The results of the analysis showed that the combination of ESR, CRP, synovial white blood cell count (Syn. WBC), and polymorphonuclear neutrophil percentage (PMN%) with PVR had the highest AUC of 0.99 for knees, with sensitivity of 97.73% and specificity of 100%. Similarly, for hips, this combination had an AUC of 0.98, sensitivity of 96.15%, and specificity of 100.00%. Conclusion. This study supports the use of PVR calculated from readily available complete blood counts, combined with established markers, to improve the accuracy in diagnosing chronic PJI in both total hip and knee arthroplasties. Cite this article: Bone Jt Open 2023;4(11):881–888

Aims. This study aims to determine difference in annual rate of early-onset (≤ 90 days) deep surgical site infection (SSI) following primary total knee arthroplasty (TKA) for osteoarthritis, and to identify risk factors that may be associated with infection. Methods. This is a retrospective population-based cohort study using prospectively collected patient-level data between 1 January 2013 and 1 March 2020. The diagnosis of deep SSI was defined as per the Centers for Disease Control/National Healthcare Safety Network criteria. The Mann-Kendall Trend test was used to detect monotonic trends in annual rates of early-onset deep SSI over time. Multiple logistic regression was used to analyze the effect of different patient, surgical, and healthcare setting factors on the risk of developing a deep SSI within 90 days from surgery for patients with complete data. We also report 90-day mortality. Results. A total of 39,038 patients underwent primary TKA for osteoarthritis during the study period. Of these, 275 patients developed a deep SSI within 90 days of surgery, representing a cumulative incidence of 0.7%. The annual infection rate did not significantly decrease over the seven-year study period (p = 0.162). Overall, 13,885 (35.5%) cases were excluded from the risk analysis due to missing data. Risk factors associated with early-onset deep SSI included male sex, American Society of Anesthesiologists grade ≥ 3, blood transfusion, acute length of stay, and surgeon volume < 30 TKAs/year. Early-onset deep SSI was not associated with increased 90-day mortality. Conclusion. This study establishes a reliable baseline infection rate for early-onset deep SSI after TKA for osteoarthritis using robust Infection Prevention and Control surveillance data, and identifies several potentially modifiable risk factors. Cite this article: Bone Joint J 2023;105-B(9):971–976

Aims. Fungal periprosthetic joint infections (PJIs) are rare, but their diagnosis and treatment are highly challenging. The purpose of this study was to investigate the clinical outcomes of patients with fungal PJIs treated with two-stage exchange knee arthroplasty combined with prolonged antifungal therapy. Methods. We reviewed our institutional joint arthroplasty database and identified 41 patients diagnosed with fungal PJIs and treated with two-stage exchange arthroplasty after primary total knee arthroplasty (TKA) between January 2001 and December 2020, and compared them with those who had non-fungal PJIs during the same period. After propensity score matching based on age, sex, BMI, American Society of Anesthesiologists grade, and Charlson Comorbidity Index, 40 patients in each group were successfully matched. The surgical and antimicrobial treatment, patient demographic and clinical characteristics, recurrent infections, survival rates, and relevant risk factors that affected joint survivorship were analyzed. We defined treatment success as a well-functioning arthroplasty without any signs of a PJI, and without antimicrobial suppression, at a minimum follow-up of two years from the time of reimplantation. Results. The fungal PJI group demonstrated a significantly worse treatment success rate at the final follow-up than the non-fungal PJI group (65.0% (26/40) vs 85.0% (34/40); p < 0.001). The mean prosthesis-free interval was longer in the fungal PJI group than in the non-fungal PJI group (6.7 weeks (SD 5.8) vs 4.1 weeks (SD 2.5); p = 0.020). The rate of survivorship free from reinfection was worse in the fungal PJI group (83.4% (95% confidence interval (CI) 64.1 to 92.9) at one year and 76.4% (95% CI 52.4 to 89.4) at two years) than in the non-fungal PJI group (97.4% (95% CI 82.7 to 99.6) at one year and 90.3% (95% CI 72.2 to 96.9) at two years), but the differences were not significant (p = 0.270). Cox proportional hazard regression analysis identified the duration of the prosthesis-free interval as a potential risk factor for failure (hazard ratio 1.128 (95% CI 1.003 to 1.268); p = 0.043). Conclusion. Fungal PJIs had a lower treatment success rate than non-fungal PJIs despite two-stage revision arthroplasty and appropriate antifungal treatment. Our findings highlight the need for further developments in treating fungal PJIs. Cite this article: Bone Joint J 2023;105-B(12):1286–1293

Aims. Achievement of accurate microbiological diagnosis prior to revision is key to reducing the high rates of persistent infection after revision knee surgery. The effect of change in the microorganism between the first- and second-stage revision of total knee arthroplasty for periprosthetic joint infection (PJI) on the success of management is not clear. Methods. A two-centre retrospective cohort study was conducted to review the outcome of patients who have undergone two-stage revision for treatment of knee arthroplasty PJI, focusing specifically on isolated micro-organisms at both the first- and second-stage procedure. Patient demographics, medical, and orthopaedic history data, including postoperative outcomes and subsequent treatment, were obtained from the electronic records and medical notes. Results. The study cohort consisted of 84 patients, of whom 59.5% (n = 50) had successful eradication of their infection at a mean follow-up of 4.7 years. For the 34 patients who had recurrence of infection, 58.8% (n = 20) had a change in isolated organism, compared to 18% (n = 9) in the infection eradication group (p < 0.001). When adjusting for confound, there was no association when the growth on the second stage was the same as the first (odd ratio (OR) 2.50, 95% confidence interval (CI) 0.49 to 12.50; p = 0.269); however, when a different organism was identified at the second stage, this was independently associated with failure of treatment (OR 8.40, 95% CI 2.91 to 24.39; p < 0.001). There were no other significant differences between the two cohorts with regard to patient demographics or type of organisms isolated. Conclusion. Change in the identified microorganism between first- and second-stage revision for PJI was associated with failure of management. Identification of this change in the microorganism prior to commencement of the second stage may help target antibiotic management and could improve the success of surgery in these patients. Cite this article: Bone Jt Open 2023;4(9):720–727

Aims. Periprosthetic joint infection (PJI) occurs in approximately 1% to 2% of total knee arthroplasties (TKA) presenting multiple challenges, such as difficulty in diagnosis, technical complexity, and financial costs. Two-stage exchange is the gold standard for treating PJI but emerging evidence suggests 'two-in-one' single-stage revision as an alternative, delivering comparable outcomes, reduced morbidity, and cost-effectiveness. This study investigates five-year results of modified single-stage revision for treatment of PJI following TKA with bone loss. Methods. Patients were identified from prospective data on all TKA patients with PJI following the primary procedure. Inclusion criteria were: revision for PJI with bone loss requiring reconstruction, and a minimum five years’ follow-up. Patients were followed up for recurrent infection and assessment of function. Tools used to assess function were Oxford Knee Score (OKS) and American Knee Society Score (AKSS). Results. A total of 24 patients were included with a mean age of 72.7 years (SD 7.6), mean BMI of 33.3 kg/m. 2. (SD 5.7), and median ASA grade of 2 (interquartile range 2 to 4). Mean time from primary to revision was 3.0 years (10 months to 8.3 years). At revision, six patients had discharging sinus and three patients had negative cultures from tissue samples or aspirates. Two patients developed recurrence of infection: one was treated successfully with antibiotic suppression and one underwent debridement, antibiotics, and implant retention. Mean AKSS scores at two years showed significant improvement from baseline (27.1 (SD 10.2 ) vs 80.3 (SD 14.8); p < 0.001). There was no significant change in mean AKSS scores between two and five years (80.3 (SD 14.8 ) vs 74.1 (SD 19.8); p = 0.109). Five-year OKS scores were not significantly different compared to two-year scores (36.17 (SD 3.7) vs 33.0 (SD 8.5); p = 0.081). Conclusion. ‘Two-in-one’ single-stage revision is effective for treating PJI following TKA with bone loss, providing patients with sustained improvements in outcomes and infection clearance up to five years post-procedure. Cite this article: Bone Jt Open 2022;3(2):107–113

Aims. The aim of this study was to determine if a three-month course of microorganism-directed oral antibiotics reduces the rate of failure due to further infection following two-stage revision for chronic prosthetic joint infection (PJI) of the hip and knee. Methods. A total of 185 patients undergoing a two-stage revision in seven different centres were prospectively enrolled. Of these patients, 93 were randomized to receive microorganism-directed oral antibiotics for three months following reimplantation; 88 were randomized to receive no antibiotics, and four were withdrawn before randomization. Of the 181 randomized patients, 28 were lost to follow-up, six died before two years follow-up, and five with culture negative infections were excluded. The remaining 142 patients were followed for a mean of 3.3 years (2.0 to 7.6) with failure due to a further infection as the primary endpoint. Patients who were treated with antibiotics were also assessed for their adherence to the medication regime and for side effects to antibiotics. Results. Nine of 72 patients (12.5%) who received antibiotics failed due to further infection compared with 20 of 70 patients (28.6%) who did not receive antibiotics (p = 0.012). Five patients (6.9%) in the treatment group experienced adverse effects related to the administered antibiotics severe enough to warrant discontinuation. Conclusion. This multicentre randomized controlled trial showed that a three-month course of microorganism-directed, oral antibiotics significantly reduced the rate of failure due to further infection following a two-stage revision of total hip or knee arthroplasty for chronic PJI. Cite this article: Bone Joint J 2020;102-B(6 Supple A):3–9

Aims. The diagnosis of periprosthetic joint infection (PJI) continues to present a significant clinical challenge. New biomarkers have been proposed to support clinical decision-making; among them, synovial fluid alpha-defensin has gained interest. Current research methodology suggests reference methods are needed to establish solid evidence for use of the test. This prospective study aims to evaluate the diagnostic accuracy of high-performance liquid chromatography coupled with the mass spectrometry (LC-MS) method to detect alpha-defensin in synovial fluid. Methods. Between October 2017 and September 2019, we collected synovial fluid samples from patients scheduled to undergo revision surgery for painful total knee arthroplasty (TKA). The International Consensus Meeting criteria were used to classify 33 PJIs and 92 aseptic joints. LC-MS assay was performed to measure alpha-defensin in synovial fluid of all included patients. Sensitivity, specificity, positive predictive value, negative predictive value, and the area under the receiver operating characteristic curve (AUC) were calculated to define the test diagnostic accuracy. Results. The AUC was 0.99 (95% confidence interval (CI) 0.98 to 1.00). Receiver operating characteristic (ROC) analysis showed that the optimal cut-off value of synovial fluid alpha-defensin was 1.0 μg/l. The sensitivity of alpha-defensin was 100% (95% CI 96 to 100), the specificity was 97% (95% CI 90 to 98), the positive predictive value was 89.2% (95% CI 82 to 94), and negative predictive value was 100% (95% CI 96 to 100). ROC analysis demonstrated an AUC of 0.99 (95% CI 0.98 to 1.0). Conclusion. The present study confirms the utility of alpha-defensin in the synovial fluid in patients with painful TKA to select cases of PJI. Since LC-MS is still a time-consuming technology and is available in highly specialized laboratories, further translational research studies are needed to take this evidence into routine procedures and promote a new diagnostic approach. Cite this article: Bone Joint J 2022;104-B(9):1047–1051

Aims. Debridement, antibiotics, and implant retention (DAIR) remains one option for the treatment of acute periprosthetic joint infection (PJI) despite imperfect success rates. Intraosseous (IO) administration of vancomycin results in significantly increased local bone and tissue concentrations compared to systemic antibiotics alone. The purpose of this study was to evaluate if the addition of a single dose of IO regional antibiotics to our protocol at the time of DAIR would improve outcomes. Methods. A retrospective case series of 35 PJI TKA patients, with a median age of 67 years (interquartile range (IQR) 61 to 75), who underwent DAIR combined with IO vancomycin (500 mg), was performed with minimum 12 months' follow-up. A total of 26 patients with primary implants were treated for acute perioperative or acute haematogenous infections. Additionally, nine patients were treated for chronic infections with components that were considered unresectable. Primary outcome was defined by no reoperations for infection, nor clinical signs or symptoms of PJI. Results. Mean follow-up for acute infection was 16.5 months (12.1 to 24.2) and 15.8 months (12 to 24.8) for chronic infections with unresectable components. Overall non-recurrence rates for acute infection was 92.3% (24/26) but only 44.4% (4/9) for chronic infections with unresectable components. The majority of patients remained on suppressive oral antibiotics. Musculoskeletal Infection Society (MSIS) host grade was a significant indicator of failure (p < 0.001). Conclusion. The addition of IO vancomycin at the time of DAIR was shown to be safe with improved results compared to current literature using standard DAIR without IO antibiotic administration. Use of this technique in chronic infections should be applied with caution. While these results are encouraging, this technique requires longer follow-up before widespread adoption. Cite this article: Bone Joint J 2021;103-B(6 Supple A):185–190

Aims. Single-stage revision total knee arthroplasty (rTKA) is gaining popularity in treating chronic periprosthetic joint infections (PJIs). We have introduced this approach to our clinical practice and sought to evaluate rates of reinfection and re-revision, along with predictors of failure of both single- and two-stage rTKA for chronic PJI. Methods. A retrospective comparative cohort study of all rTKAs for chronic PJI between 1 April 2003 and 31 December 2018 was undertaken using prospective databases. Patients with acute infections were excluded; rTKAs were classified as single-stage, stage 1, or stage 2 of two-stage revision. The primary outcome measure was failure to eradicate or recurrent infection. Variables evaluated for failure by regression analysis included age, BMI, American Society of Anesthesiologists grade, infecting organisms, and the presence of a sinus. Patient survivorship was also compared between the groups. Results. A total of 292 consecutive first-time rTKAs for chronic PJI were included: 82 single-stage (28.1%); and 210 two-stage (71.9%) revisions. The mean age was 71 years (27 to 90), with 165 females (57.4%), and a mean BMI of 30.9 kg/m. 2. (20 to 53). Significantly more patients with a known infecting organism were in the single-stage group (93.9% vs 80.47%; p = 0.004). The infecting organism was identified preoperatively in 246 cases (84.2%). At a mean follow-up of 6.3 years (2.0 to 17.6), the failure rate was 6.1% in the single-stage, and 12% in the two-stage groups. All failures occurred within four years of treatment. The presence of a sinus was an independent risk factor for failure (odds ratio (OR) 4.97; 95% confidence interval (CI) 1.593 to 15.505; p = 0.006), as well as age > 80 years (OR 5.962; 95% CI 1.156 to 30.73; p = 0.033). The ten-year patient survivorship rate was 72% in the single-stage group compared with 70.5% in the two-stage group. This difference was not significant (p = 0.517). Conclusion. Single-stage rTKA is an effective strategy with a high success rate comparable to two-stage approach in appropriately selected patients. Cite this article: Bone Joint J 2021;103-B(8):1373–1379

Aims. The outcome of repeat septic revision after a failed one-stage exchange for periprosthetic joint infection (PJI) in total knee arthroplasty (TKA) remains unknown. The aim of this study was to report the infection-free and all-cause revision-free survival of repeat septic revision after a failed one-stage exchange, and to determine whether the Musculoskeletal Infection Society (MSIS) stage is associated with subsequent infection-related failure. Methods. We retrospectively reviewed all repeat septic revision TKAs which were undertaken after a failed one-stage exchange between 2004 and 2017. A total of 33 repeat septic revisions (29 one-stage and four two-stage) met the inclusion criteria. The mean follow-up from repeat septic revision was 68.2 months (8.0 months to 16.1 years). The proportion of patients who had a subsequent infection-related failure and all-cause revision was reported and Kaplan-Meier survival for these endpoints was determined. Patients were categorized according to the MSIS staging system, and the association with subsequent infection was analyzed. Results. At the most recent follow-up, 17 repeat septic revisions (52%) had a subsequent infection-related failure and the five-year infection-free survival was 59% (95% confidence interval (CI) 39 to 74). A total of 19 underwent a subsequent all-cause revision (58%) and the five-year all-cause revision-free survival was 47% (95% CI 28 to 64). The most common indication for the first subsequent aseptic revision was loosening. The MSIS stage of the host status (p = 0.663) and limb status (p = 1.000) were not significantly associated with subsequent infection-related failure. Conclusion. Repeat septic revision after a failed one-stage exchange TKA for PJI is associated with a high rate of subsequent infection-related failure and all-cause revision. Patients should be counselled appropriately to manage expectations. The host and limb status according to the MSIS staging system were not associated with subsequent infection-related failure. Cite this article: Bone Joint J 2022;104-B(3):386–393

Aims. It remains difficult to diagnose early postoperative periprosthetic joint infection (PJI) following total knee arthroplasty (TKA). We aimed to validate the optimal cutoff values of ESR, CRP, and synovial fluid analysis for detecting early postoperative PJI in a large series of primary TKAs. Methods. We retrospectively identified 27,066 primary TKAs performed between 2000 and 2019. Within 12 weeks, 169 patients (170 TKAs) had an aspiration. The patients were divided into two groups: those evaluated ≤ six weeks, or between six and 12 weeks postoperatively. The 2011 Musculoskeletal Infection Society (MSIS) criteria for PJI diagnosis in 22 TKAs. The mean follow-up was five years (two months to 17 years). The results were compared using medians and Mann-Whitney U tests and thresholds were analyzed using receiver operator characteristic curves. Results. Within six weeks, the median CRP (101 mg/l vs 35 mg/l; p = 0.011), synovial WBCs (58,295 cells/μl vs 2,121 cells/μl; p ≤ 0.001), percentage of synovial neutrophils (91% vs 71% (p < 0.001), and absolute synovial neutrophil count (ANC) (50,748 cells/μl vs 1,386 cells/μl (p < 0.001) were significantly higher in infected TKAs. Between six and 12 weeks, the median CRP (85 mg/l vs 5 mg/l (p < 0.001)), ESR (33 mm/hr vs 14 mm/hr (p = 0.015)), synovial WBCs (62,247 cells/μl vs 620 cells/μl (p < 0.001)), percentage of synovial neutrophils (93% vs 54% (p < 0.001)), and ANC (55,911 cells/μl vs 326 cells/μl (p < 0.001)) were also significantly higher in infected TKAs. Optimal thresholds at ≤ six weeks were: CRP ≥ 82 mg/l (sensitivity 70%, specificity 77%), synovial WBCs ≥ 8,676 cells/μl (83%, 90%), percentage of synovial neutrophils ≥ 88% (67%, 78%), and ANC ≥ 8,346 cells/μl (83%, 91%). Between six and 12 weeks, thresholds were: CRP ≥ 34 mg/l (90%, 93%), synovial WBCs ≥ 1,983 cells/μl (80%, 85%), percentage of synovial neutrophils ≥ 76% (80%, 81%), and ANC ≥ 1,684 cells/μl (80%, 87%). Conclusion. Early PJI after TKA should be suspected within six weeks if the CRP is ≥ 82 mg/l, synovial WBCs are ≥ 8,676 cells/μl, the percentage of synovial neutrophils is ≥ 88%, and/or the ANC is ≥ 8,346 cells/μl. Between six and 12 weeks, thresholds include a CRP of ≥ 34 mg/l, synovial WBC of ≥ 1,983 cells/μl, a percentage of synovial neutrophils of ≥ 76%, and/or an ANC of ≥ 1,684 cells/μl. Cite this article: Bone Joint J 2021;103-B(6 Supple A):177–184

Aims. Infection complicating primary total knee arthroplasty (TKA) is a common reason for revision surgery, hospital readmission, patient morbidity, and mortality. Increasing incidence of methicillin-resistant Staphylococcus aureus (MRSA) is a particular concern. The use of vancomycin as prophylactic agent alone or in combination with cephalosporin has not demonstrated lower periprosthetic joint infection (PJI) rates, partly due to timing and dosing of intravenous (IV) vancomycin administration, which have proven important factors in effectiveness. This is a retrospective review of a consecutive series of primary TKAs examining incidence of PJI, adverse reactions, and complications using IV versus intraosseous (IO) vancomycin at 30-day, 90-day, and one-year follow-up. Methods. A retrospective review of 1,060 patients who underwent TKA between May 2016 to July 2020 was performed. There were 572 patients in the IV group and 488 in the IO group, with minimal 30 days of follow-up. Patients were followed up at regularly scheduled intervals (two, six, and 12 weeks). No differences between groups for age, sex, BMI, or baseline comorbidities existed. The IV group received an IV dose of 15 mg/kg vancomycin given over an hour preceding skin incision. The IO group received a 500 mg dose of vancomycin mixed in 150 ml of normal saline, injected into proximal tibia after tourniquet inflation, before skin incision. All patients received an additional dose of first generation cephalosporin. Evaluation included preoperative and postoperative serum creatinine values, tourniquet time, and adverse reactions attributable to vancomycin. Results. Incidence of PJI with minimum 90-day follow-up was 1.4% (eight knees) in the IV group and 0.22% (one knee) in IO group (p = 0.047). This preliminary report demonstrated an reduction in the incidence of infection in TKA using IO vancomycin combined with a first-generation cephalosporin. While the study suffers from limitations of a retrospective, multi-surgeon investigation, early findings are encouraging. Conclusion. IO delivery of vancomycin after tourniquet inflation is a safe and effective alternative to IV administration, eliminating the logistical challenges of timely dosing. Cite this article: Bone Joint J 2021;103-B(6 Supple A):13–17

Aims. The management of periprosthetic joint infection (PJI) after total knee arthroplasty (TKA) is challenging. The correct antibiotic management remains elusive due to differences in epidemiology and resistance between countries, and reports in the literature. Before the efficacy of surgical treatment is investigated, it is crucial to analyze the bacterial strains causing PJI, especially for patients in whom no organisms are grown. Methods. A review of all revision TKAs which were undertaken between 2006 and 2018 in a tertiary referral centre was performed, including all those meeting the consensus criteria for PJI, in which organisms were identified. Using a cluster analysis, three chronological time periods were created. We then evaluated the antibiotic resistance of the identified bacteria between these three clusters and the effectiveness of our antibiotic regime. Results. We identified 129 PJIs with 161 culture identified bacteria in 97 patients. Coagulase-negative staphylococci (CNS) were identified in 46.6% cultures, followed by Staphylococcus aureus in 19.8%. The overall resistance to antibiotics did not increase significantly during the study period (p = 0.454). However, CNS resistance to teicoplanin (p < 0.001), fosfomycin (p = 0.016), and tetracycline (p = 0.014) increased significantly. Vancomycin had an 84.4% overall sensitivity and 100% CNS sensitivity and was the most effective agent. Conclusion. Although we were unable to show an overall increase in antibiotic resistance in organisms that cause PJI after TKA during the study period, this was not true for CNS. It is concerning that resistance of CNS to new antibiotics, but not vancomycin, has increased in a little more than a decade. Our findings suggest that referral centres should continuously monitor their bacteriological analyses, as these have significant implications for prophylactic treatment in both primary arthroplasty and revision arthroplasty for PJI. Cite this article: Bone Joint J 2021;103-B(6 Supple A):171–176

Aims. To describe the risk of periprosthetic joint infection (PJI) and reoperation in patients who have an acute, traumatic wound dehiscence following total knee arthroplasty (TKA). Methods. From January 2002 to December 2018, 16,134 primary TKAs were performed at a single institution. A total of 26 patients (0.1%) had a traumatic wound dehiscence within the first 30 days. Mean age was 68 years (44 to 87), 38% (n = 10) were female, and mean BMI was 34 kg/m. 2. (23 to 48). Median time to dehiscence was 13 days (interquartile range (IQR) 4 to 15). The dehiscence resulted from a fall in 22 patients and sudden flexion after staple removal in four. The arthrotomy was also disrupted in 58% (n = 15), including a complete extensor mechanism disruption in four knees. An irrigation and debridement with component retention (IDCR) was performed within 48 hours in 19 of 26 knees and two-thirds were discharged on antibiotic therapy. The mean follow-up was six years (2 to 15). The association of wound dehiscence and the risk of developing a PJI was analyzed. Results. Patients who sustained a traumatic wound dehiscence had a 6.5-fold increase in the risk of PJI (95% confidence interval (CI) 1.6 to 26.2; p = 0.008). With the small number of PJIs, no variables were found to be significant risk factors. However, there were no PJIs in any of the patients who were treated with IDCR and a course of antibiotics. Three knees required reoperation including one two-stage exchange for PJI, one repeat IDCR for PJI, and one revision for aseptic loosening of the tibial component. Conclusion. Despite having a traumatic wound dehiscence, the risk of PJI was low, but much higher than experienced in all other TKAs during the same period. We recommend urgent IDCR and a course of postoperative antibiotics to decrease the risk of PJI. A traumatic wound dehiscence increases risk of PJI by 6.5-fold. Cite this article: Bone Joint J 2021;103-B(6 Supple A):191–195

Aims. The aim of this study was to identify risk factors for prosthetic joint infection (PJI) following total knee arthroplasty (TKA). . Patients and Methods. The New Zealand Joint Registry database was analysed, using revision surgery for PJI at six and 12 months after surgery as primary outcome measures. Statistical associations between revision for infection, with common and definable surgical and patient factors were tested. Results. A total of 64 566 primary TKAs have been recorded on the registry between 1999 and 2012 with minimum follow-up of 12 months. Multivariate analysis showed statistically significant associations with revision for PJI between male gender (odds ratio (OR) 1.85, 95% confidence interval (CI) 1.24 to 2.74), previous surgery (osteotomy (OR 2.45 95% CI 1.2 to 5.03), ligament reconstruction (OR 1.85, 95% CI 0.68 to 5.00)), the use of laminar flow (OR 1.6, 95% CI 1.04 to 2.47) and the use of antibiotic-laden cement (OR 1.93, 95% CI 1.19 to 3.13). There was a trend towards significance (p = 0.052) with the use of surgical helmet systems at six months (OR 1.53, 95% CI 1.00 to 2.34). Conclusion. These findings show that patient factors remain the most important in terms of predicting early PJI following TKA. Furthermore, we found no evidence that modern surgical helmet systems reduce the risk of PJI and laminar flow systems may actually increase risk in TKA. The use of this registry data assists the estimation of the risk of PJI for individual patients, which is important for both informed consent and the interpretation of infection rates at different institutions. . Take home message: Infection rates in TKA are related to both individual patient and surgical factors, and some modern methods of reducing infection may actually increase infection risk. . Cite this article: Bone Joint J 2016;98-B:334–40