A Case of Severe Acute Kidney Injury Due to an Antibiotic-Loaded Cement Spacer for Infected Knee Arthroplasty.

The treatment for periprosthetic joint infection frequently involves the placement of a high-dose antibiotic-loaded bone cement spacer (ALCS) into the debrided joint. Typical antibiotics in the spacer include aminoglycosides and vancomycin. It has been believed that systemic absorption of intraarticular antibiotics would be low and early experience suggested that the risk of acute kidney injury (AKI) from ALCS was minimal. However, recent case reports and case series have suggested a risk of acute kidney injury due to antibiotic absorption, though confounding factors are common. We report a case of severe AKI requiring hemodialysis with extremely high systemic tobramycin levels after the placement of an ALCS with increased dosing of antibiotics after previous failure to resolve a periprosthetic joint infection with a prior ALCS. There was no concomitant use of intravenous nephrotoxic antibiotics nor other confounding factors. Despite dialysis, the patient needed urgent removal of the ALCS to control tobramycin levels with subsequent resolution of the AKI. This case highlights the potentially serious nephrotoxicity of ALCS's, the importance of antibiotic type and dosing, and the value of close monitoring after ALCS placement, especially in a patient with chronic kidney disease.

Static spacers play a crucial role in the treatment of complex periprosthetic joint infections of the knee.

PURPOSE: To determine the superior spacer design, a growing number of studies are comparing treatment results between patients having been treated with articulating and static knee spacers in the setting of two-stage revision for periprosthetic joint infection (PJI). In contrast, the primary objective of this study was to compare preoperative characteristics between patients from both spacer groups and examine whether significant differences were present prior to spacer implantation. METHODS: This retrospective, single-centre, cohort study examined the preoperative situation of 80 consecutive knee PJIs between 2017 and 2020. All patients underwent two-stage revision, with 35 (44%) receiving an articulating and 45 (56%) a static spacer. RESULTS: No significant differences were observed in terms of patient gender (p = 0.083), age (p = 0.666), comorbidity (p = 0.1) and preoperative clinical function (p = 0.246). Static spacers were significantly more often used in the presence of a periarticular fistula (p = 0.033), infection of a revision implant (p < 0.001), higher degree of bone loss (p < 0.001) and infection caused by a difficult-to-treat pathogen (p = 0.038). Complication and revision rates were similar for both spacer types during the interim period, while patients with articulating spacers demonstrated a superior clinical function (p < 0.001) during the interim period and after reimplantation. CONCLUSION: Static spacers are being utilised in significantly more complex and unfavourable preoperative scenarios. Therefore, a preoperative selection bias may be at least partially accountable for any disparities observed in postoperative outcomes. To achieve the best possible results, surgeons should know and respect the distinct indications of static and articulating spacers and consequently understand and use them as complementary surgical options. LEVEL OF EVIDENCE: Level III.

Synovial Calprotectin is Superior to Synovial Leukocyte Count in Excluding Chronic Periprosthetic Joint Infections, a Retrospective Cohort Study.

BACKGROUND: Synovial calprotectin is a promising biomarker for diagnosing chronic periprosthetic joint infections (PJIs), but its diagnostic value has not been directly compared to synovial leukocyte count and polymorphonuclear neutrophils. This study aimed to: (1) evaluate and compare the diagnostic accuracy between these markers in patients undergoing revision arthroplasty for chronic PJI or aseptic reasons; and (2) determine the best rule-out and rule-in test for PJI. METHODS: Synovial fluid samples from patients undergoing revision arthroplasty in hip and knee joints were collected and analyzed. Patients diagnosed with an acute PJI, patients treated with antibiotics 2 weeks prior to revision surgery, and/or patients who had active inflammatory joint disease were excluded. Periprosthetic joint infections were diagnosed based on the presence of a sinus tract and/or positive intraoperative cultures according to the European Bone and Joint Infection Society microbiological criteria. RESULTS: A total of 137 patients were included, of whom 19 (14%) were diagnosed with a PJI. Overall, synovial calprotectin had the highest diagnostic accuracy of all studied markers (area under the curve 96%). Synovial calprotectin, with a cutoff of 50 mg/L, had the highest negative predictive value of 100%. However, PMNs (> 80%) combined with a leukocyte count (> 3,000 cells/µL) showed the highest positive likelihood ratio of an infection (PLR 17). CONCLUSIONS: Synovial calprotectin is the most accurate biomarker for ruling out a chronic PJI, while the combination of synovial leukocyte count and PMN is most reliable for ruling in a chronic PJI.

Periprosthetic Hip and Knee Infection: Is an Ipsilateral Uninfected Total Joint Arthroplasty at Risk?

BACKGROUND: Periprosthetic joint infections (PJIs) of total hip arthroplasty (THA) or total knee arthroplasty (TKA) may occur in the setting of an uninfected ipsilateral prosthetic joint. However, the risk to that uninfected ipsilateral joint is unknown. We analyzed the survivorship free from PJI in at risk THAs and TKAs following treatment of an ipsilateral knee or hip PJI, respectively. METHODS: Using our institutional total joint registry, we identified 205 patients who underwent treatment for PJI (123 THAs and 83 TKAs) with an at-risk ipsilateral in situ knee or hip, respectively, between 2000 and 2019. In total, 54% of index PJIs were chronic and 46% were acute. The mean age was 70 years, 47% were female, and the mean body mass index was 32. Kaplan-Meier survivorship analyses were performed. Mean follow-up was 6 years. RESULTS: The 5-year survivorship free of PJI in an at-risk THA after an ipsilateral TKA was treated for PJI was 97%. The 5-year survivorship free of PJI in an at-risk TKA when the ipsilateral THA was treated for PJI was 99%. Three PJIs occurred (2 THAs and 1 TKA), all over 1 year from the index ipsilateral PJI treatment. One hip PJI was an acute hematogenous infection that resulted from pneumonia. The other 2 new PJIs were caused by the same organism as the index PJI and were due to a failure of source control at the index joint. CONCLUSIONS: When diagnosed with PJI in a single joint, the risk of developing PJI in an ipsilateral prosthetic joint within 5 years was low (1 to 3% risk). In the rare event of an ipsilateral infection, all occurred greater than one year from the index PJI and 2 of 3 were with the same organism when source infection control failed. LEVEL OF EVIDENCE: Prognostic Level III.

Therapeutic Efficacy of an Erythromycin-Loaded Coaxial Nanofiber Coating in a Rat Model of S. aureus-Induced Periprosthetic Joint Infection.

Implant surface nanofiber (NF) coatings represent an alternative way to prevent/treat periprosthetic joint infection (PJI) via local drug release. We developed and characterized a coaxial erythromycin (EM)-doped PLGA/PCL-PVA NF coating. The purpose of this study was to determine the efficacy of EM-NF coatings (EM0, no EM, EM100 (100 mg/mL), and EM1000 (1000 mg/mL) wt/wt) in a rat PJI model. A strong bond of the EM-NF coating to the surface of titanium (Ti) pins was confirmed by in vitro mechanical testing. Micro-computed tomography (mCT) analysis showed that both EM100 and EM1000 NF effectively reduced periprosthetic osteolysis compared to EM0 at 8 and 16 weeks after implantation. Histology showed that EM100 and EM1000 coatings effectively controlled infection and enhanced periprosthetic new bone formation. The bone implant contact (BIC) of EM100 (35.08%) was higher than negative controls and EM0 (3.43% and 0%, respectively). The bone area fraction occupancy (BAFO) of EM100 (0.63 mm2) was greater than controls and EM0 (0.390 mm2 and 0.0 mm2, respectively). The BAFO of EM100 was higher than that of EM1000 (0.3 mm2). These findings may provide a basis for a new implant surface fabrication strategy aimed at reducing the risks of defective osseointegration and PJI.

The role of advanced metal artifact reduction MRI in the diagnosis of periprosthetic joint infection.

Identification and diagnosis of periprosthetic joint infection (PJI) are challenging, requiring a multi-disciplinary approach involving clinical evaluation, laboratory tests, and imaging studies. MRI is advantageous to alternative imaging techniques due to superior soft tissue contrast and absence of ionizing radiation. However, the presence of metallic implants can cause signal loss and artifacts. Metal artifact suppression (MARS) MRI techniques have been developed that mitigate metal artifacts and improve periprosthetic soft tissue visualization. This paper provides a review of the various MARS MRI techniques, their clinical applicability and accuracy in PJI diagnosis and evaluation, and current challenges and future perspectives.

Modular Proximal Body Exchange for Re-Revision Total Hip Arthroplasty: Rarely Utilized and Moderately Successful.

BACKGROUND: Modular fluted tapered stems (MFTSs) are commonly used in revision total hip arthroplasty (THA) and provide the option of exchanging the proximal modular portion to address future surgical problems without complete femoral revision. We are unaware of any data documenting the frequencies, indications, and outcomes of modular proximal body exchange in re-revision THA. METHODS: Between 1997 and 2019, we performed 57 modular proximal body exchanges among 8,079 revision THAs at our institution. Indications and outcomes were documented at a mean follow-up of 3.4 years (range, 0 to 12.8). RESULTS: Modular proximal body exchange was performed on 47 of 1,375 (3%) of MFTSs implanted. The indications for all 57 modular proximal body exchanges performed during the study period were dislocation in 30 (53%), partial resection for periprosthetic joint infection (PJI) in 13 (23%), modular junction failure in 8 (14%), surgical exposure in 4 (7%), and concurrently with trochanteric osteotomy nonunion fixation in 2 (4%). At the final follow-up, subsequent re-revisions occurred in 10 of 30 (33%) of modular proximal body exchanges indicated for dislocation and in 5 of 13 of those indicated for PJI. One modular junction subsequently fractured after modular proximal body exchange. CONCLUSION: Modular proximal body exchange of a MFTS is an uncommon procedure most often performed for treatment of hip dislocation or PJI. It is moderately successful with approximately one-third of cases requiring subsequent re-revision. This procedure is often performed with modular component exchange alone, but can also be helpful to facilitate complex acetabular exposure. These data provide useful information to surgeons and patients undergoing this procedure. LEVEL OF EVIDENCE: IV.

Interaction of Bacteria, Immune Cells, and Surface Topography in Periprosthetic Joint Infections.

The incidence of periprosthetic joint infections (PJIs) is ~2% of total procedures and it is expected to rise due to an ageing population. Despite the large burden PJI has on both the individual and society, the immune response to the most commonly isolated pathogens, i.e., Staphylococcus aureus and Staphylococcus epidermidis, remains incompletely understood. In this work, we integrate the analysis of synovial fluids from patients undergoing hip and knee replacement surgery with in-vitro experimental data obtained using a newly developed platform, mimicking the environment of periprosthetic implants. We found that the presence of an implant, even in patients undergoing aseptic revisions, is sufficient to induce an immune response, which is significantly different between septic and aseptic revisions. This difference is confirmed by the presence of pro- and anti-inflammatory cytokines in synovial fluids. Moreover, we discovered that the immune response is also dependent on the type of bacteria and the topography of the implant surface. While S. epidermidis seems to be able to hide better from the attack of the immune system when cultured on rough surfaces (indicative of uncemented prostheses), S. aureus reacts differently depending on the contact surface it is exposed to. The experiments we performed in-vitro also showed a higher biofilm formation on rough surfaces compared to flat ones for both species, suggesting that the topography of the implant could influence both biofilm formation and the consequent immune response.

How do pre-operative intra-articular injections impact periprosthetic joint infection risk following primary total hip arthroplasty? A systematic review and meta-analysis.

INTRODUCTION: Although intra-articular injections (IAIs) serve as the first-line non-surgical management for severe osteoarthritis (OA), recent analyses have suggested they are associated with an increased infection risk following primary total hip arthroplasty (THA). Therefore, our systematic review and meta-analysis explored the relationship between IAIs and periprosthetic joint infection (PJI) following THA reported in the current literature. METHODS: Five online databases were queried for analyses published from January 1st, 2000-May 1st, 2021 reporting on PJI rates between patients undergoing primary THA who did and did not preoperatively receive an IAI. The overall pooled effect of injection status on PJI incidence was determined using Mantel-Haenszel (M-H) models. This was similarly conducted for segregated preoperative intervals: 0-3 months, > 3-6 months, > 6 + months. RESULTS: A total of 11 articles were included in our analysis reporting on 278,782 THAs (IAI: n = 41,138; no IAI: n = 237,644). Patients receiving pre-operative injections had a significantly higher risk of PJI (OR: 1.31, 95% CI 1.07-1.62; p = 0.009). However, this finding was not robust. IAI receipt within 3-months of THA was associated with significantly higher PJI rates (OR: 1.68, 95% CI 1.48-1.90; p < 0.001). However, no significant difference was demonstrated in the > 3-6 month (OR: 1.19, 95% CI 0.94-1.52; p = 0.16) and > 6 + month sub-analyses (OR: 1.20, 95% CI 0.96-1.50; p = 0.11). The results of all sub-analyses remained were robust. DISCUSSION: Our findings suggest that patients requiring THA should wait at least 3-months following IAI to reduce post-operative infection risk. This information can help inform patients considering OA management options, as well as adult reconstruction surgeons during preoperative optimization.

Intra-articular injection receipt within 3 months prior to primary total knee arthroplasty is associated with increased periprosthetic joint infection risk.

PURPOSE: This systematic review and meta-analysis analyzed the influence of pre-operative intra-articular injections (IAI) on periprosthetic joint infection (PJI) rates after primary total knee arthroplasty (TKA). METHODS: Studies published between January 1st, 2000 and May 1st, 2021 evaluating PJI rates among TKA patients with and without IAI were identified from PubMed, Cochrane Library, MEDLINE, EBSCO Host, and Google Scholar. The pooled effect of IAI on PJI risk was calculated utilizing Mantel-Haenszel (M-H) models. Sub-analysis comparisons were conducted based on the interval from IAI to TKA: 0-3 months; > 3-6 months; > 6-12 months. The Methodological Index for Non-Randomized Studies (MINORS) and the Risk of Bias in Non-randomized Studies-of Interventions (ROBINS-I) tool were utilized to evaluate the quality of each included study. RESULTS: The present analysis included 12 studies reporting on 349,605 TKAs (IAI: n = 115,122; No IAI: n = 234,483). Patients receiving an IAI at any point prior to TKA (2850/115,122; 2.48%) had statistically significant increased risk of infection compared to patients not receiving IAIs (4479/234,483; 1.91%; OR: 1.14, 95% CI: 1.08-1.20; p < 0.0001). However, this finding was not demonstrated across sensitivity analyses. Receiving injections within 3 months prior to TKA was associated with increased infection risk (OR: 1.23, 95% CI: 1.14-1.31; p < 0.0001). There were no differences in infection rates when injections were given between > 3 and 6 months (OR: 0.82, 95% CI: 0.47-1.43; p = 0.49) and > 6-12 months prior to TKA (OR: 1.26, 95% CI: 0.89-1.78; p = 0.18). CONCLUSIONS: Based on the current literature, the findings of this analysis suggest that patients receiving IAI should wait at least 3 months before undergoing TKA to mitigate infection risk. Orthopaedic surgeons and patients can utilize this information when undergoing shared decision-making regarding osteoarthritis management options and timing. LEVEL OF EVIDENCE: Level III.

Prevalence, interpretation, and management of unexpected positive cultures in revision TKA: a systematic review.

PURPOSE: Unexpected positive intraoperative cultures (UPIC) found in revision total knee arthroplasty (TKA) are difficult to interpret. Management goes along with risks for both over- and undertreating a potential periprosthetic joint infection (PJI). The objective of this systematic review was to determine the prevalence of UPIC in revision TKA surgery, evaluate the diagnostic workup process and the postoperative treatment, and assess outcome regarding re-revision rates. METHODS: Evidence was gathered from Medline (PubMed) and Embase published from January 2000 until April 2021. Nine studies with data of UPIC in revision TKA and outcome after at least 2 years of follow-up were identified. RESULTS: The calculated prevalence of UPIC in aseptic knee revision surgery was 8.32%. However, the diagnostical approach differs as well as the used criteria to confirm PJI in presumed aseptic revision surgery. The work-up generally consists of a serum C-reactive protein and Erythrocyte Sedimentation Rate, joint fluid aspiration for culture and white blood cell count and formula, and radiographic imaging. Collection of intraoperative cultures is widely used, but inconsistent in sample amount and incubation time. Once a single UPIC is found, surgeons tend to treat it in different ways. Regarding re-revision rates, the weighted arithmetic mean in the included studies was 18.45% in the unsuspected PJI group compared to 2.94% in the aseptic group. There also seems to be a trend towards higher re-revision rates when a higher number of intraoperative cultures are positive. CONCLUSION: The interpretation of UPIC in revision TKA is of utmost importance since the decision whether to treat a UPIC as an unsuspected PJI has a major impact on implant survival and re-revision rate. Different criteria are used to differentiate between unsuspected PJI and contamination in true aseptic failure, and the heterogeneity amongst the included papers impedes to state a clear recommendation, integrating not only quantitative findings, but also qualitative data such as virulence of the identified microorganism. LEVEL OF EVIDENCE: Systematic review, III.

Extended Oral Antibiotic Prophylaxis After Aseptic Revision Total Hip Arthroplasty: Does It Decrease Infection Risk?

BACKGROUND: Extended oral antibiotic prophylaxis (EOA) has been shown to reduce infection after high-risk primary total hip arthroplasties (THAs) and reimplantations. However, data are limited regarding EOA after aseptic revision THAs. This study evaluated the impact of EOA on infection-related outcomes after aseptic revision THAs. METHODS: We retrospectively identified 1,107 aseptic revision THAs performed between 2014 and 2019. Patients who received EOA >24 hours perioperatively (n = 370) were compared to those who did not (n = 737) using an inverse probability of treatment weighting model. Their mean age was 65 years (range, 19-98 years), mean body mass index was 30 kg/m2 (range, 16-72), and 54% were women. Outcomes included cumulative probabilities of any infection, periprosthetic joint infection (PJI), and re-revision or reoperation for infection. Mean follow-up was 4 years (range, 2-8 years). RESULTS: The cumulative probability of any infection after aseptic revision THA was 2.3% at 90 days, 2.7% at 1 year, and 3.5% at 5 years. The cumulative probability of PJI was 1.7% at 90 days, 2.1% at 1 year, and 2.8% at 5 years. There was a trend toward an increased risk of any infection (hazards ratio [HR] = 2.6; P = .058), PJI (HR = 2.6; P = .085), and re-revision (HR = 6.5; P = .077) or reoperation (HR = 2.3; P = .095) for infection in patients who did not have EOA at the final clinical follow-up. CONCLUSIONS: EOA after aseptic revision THA was not associated with a statistically significant decreased risk of any infection, PJI, or re-revision or reoperation for infection at all time points. LEVEL OF EVIDENCE: Level III.

Periprosthetic joint infection rates across primary total hip arthroplasty surgical approaches: a systematic review and meta-analysis of 653,633 procedures.

INTRODUCTION: Evidence demonstrates comparable clinical outcomes across the various surgical approaches to primary total hip arthroplasty (THA). However, high-quality contemporary data regarding periprosthetic joint infection (PJI) risk between direct anterior approach (DAA) and other (THA) approaches is lacking. This systematic review and meta-analysis evaluated PJI rates reported in the literature between the DAA and other approaches. MATERIALS AND METHODS: Five online databases were queried for all studies published from January 1st, 2000 through February 17th, 2021 that reported PJI rates between DAA and other surgical approaches. Studies reporting on primary THAs for osteoarthritis (OA) and that included PJI rates segregated by surgical approach were included. Articles reporting on revision THA, alternative THA etiologies, or minimally invasive techniques were excluded. Mantel-Haenszel (M-H) models were utilized to evaluate the pooled effect of surgical approach on infection rates. Validated risk of bias and methodological quality assessment tools were applied to each study. Multiple sensitivity analyses were conducted to evaluate the robustness of analyses. RESULTS: 28 articles reporting on 653,633 primary THAs were included. No differences were found between DAA cohorts and combined other approaches (OR: 0.95; 95% CI 0.74-1.21; p = 0.67) as well as segregated anterolateral approach cohorts (OR: 0.82, 95% CI 0.64-1.06; p = 0.13). However, DAA patients had a significantly reduced risk of infection compared to those undergoing posterior (OR: 0.66, 95% CI 0.58-0.74; p < 0.0001) and direct lateral (OR: 0.56, 95% CI 0.48-0.65; p < 0.00001) approaches. CONCLUSION: The DAA to primary THA had comparable or lower PJI risk when compared to other contemporary approaches. The results of the most up-to-date evidence available serve to encourage adult reconstruction surgeons who have already adopted the DAA. Additionally, orthopaedic surgeons considering adoption or use of the direct anterior approach for other reasons should not be dissuaded over theoretical concern for a general increase in the risk of PJI. LEVEL OF EVIDENCE: Level III.

The concordance between preoperative aspiration and intraoperative synovial fluid culture results: intraoperative synovial fluid re-cultures are necessary whether the preoperative aspiration culture is positive or not.

AIMS: Preoperative aspiration culture and intraoperative cultures play pivotal roles in periprosthetic joint infection (PJI) diagnosis and pathogen identification. But the discordance between preoperative aspiration culture and intraoperative synovial fluid culture remains unknown. We aim to determine (1) the discordance between preoperative and intraoperative synovial fluid (SF) culture and. (2) compared to intraoperative synovial fluid cultures, the sensitivity of preoperative aspiration fluid culture. Then the following question is tried to be answered: Are intraoperative synovial fluid re-cultures necessary if the preoperative aspiration culture is positive? MATERIALS AND METHODS: Between 2015 and 2019, 187 PJI patients managed with surgeries were included in this study. Compared to intraoperative synovial fluid culture, the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of preoperative aspiration culture were calculated. Then, the discordance between preoperative aspiration culture and intraoperative SF culture was analyzed. RESULTS: The sensitivity of preoperative aspiration culture was 81.29% compared to intraoperative synovial fluid cultures. Concordance was identified in 147 PJI (78.61%) patients and culture discordance occurred in 40 patients (21.39%). In these discordant PJI patients, 24 patients (60%) were polymicrobial and no intraoperative synovial fluid culture growth was found in 16 PJI cases (40%). Preoperative monomicrobial staphylococcus results had a sensitivity of and a specificity of 80.43% and 83.16%, respectively. Preoperative polymicrobial results had the lowest sensitivity. CONCLUSIONS: The intraoperative synovial fluid re-cultures are necessary if the preoperative aspiration culture is positive and the discordance between preoperative aspiration culture and intraoperative synovial fluid culture should be noted especially when Streptococcus spp. and more than one pathogen was revealed by preoperative aspiration culture. LEVEL OF EVIDENCE: Level III.

Comparison of the success rate after debridement, antibiotics and implant retention (DAIR) for periprosthetic joint infection among patients with or without a sinus tract.

BACKGROUND: The relevance between the presence of a sinus tract and the failure risk after debridement, antibiotics and implant retention (DAIR) for periprosthetic joint infection (PJI) after hip or knee arthroplasty is still unclear. This study aimed to compare the success rate of DAIR between patients with or without a sinus tract and to explore the possible risk factors for failure after DAIR in patients with a sinus tract. METHODS: Consecutive DAIR cases for PJI after hip or knee arthroplasty between January 2009 and June 2019 with a minimum 1-year follow-up in two tertiary joint arthroplasty centers were included. Patients were classified into the sinus tract group and the non-sinus tract group according to the presence of a sinus tract. The success rate after DAIR were compared using Kaplan-Meier survival analysis. Potential risk factors for failure in the sinus group were also explored. RESULTS: One hundred seven patients were included. At a median 4.4 years of follow-up, 19 of 52 (36.5%) cases failed in the sinus tract group, while 15 of 55 (27.3%) cases failed in the non-sinus tract group. The 1-year and 5-year cumulative success rates were 71.2% (95% confidence interval (CI): 59.8-84.6%) and 56.8% (95% CI: 42.6-75.7%) in the sinus tract group, respectively, which were similar to the counterparts in the non-sinus tract group (P = 0.214). Among patients with a sinus tract, DAIR with the exchange of modular components showed a higher success rate (75.8% versus 47.4%, P = 0.038). CONCLUSIONS: The presence of a sinus tract does not affect the success rate of DAIR. Modular component exchange in DAIR was proposed for patients with a sinus tract for an improved infection control rate.

Irrigation and Debridement With Implant Retention: Does Chronicity of Symptoms Matter?

BACKGROUND: Periprosthetic joint infection (PJI) remains a rare, yet devastating complication of total joint arthroplasty (TJA). Chronic infection is generally considered a contraindication to debridement, antibiotics, and implant retention (DAIR); however, outcomes stratified by chronicity have not been well documented. METHODS: A retrospective review of all DAIR cases performed at a single institution from 2008 to 2015 was performed. Chronicity of PJI was categorized as acute postoperative, chronic, or acute hematogenous. Failure after DAIR, defined as re-revision for infection recurrence with the same organism, was evaluated between the 3 chronicity groups at 90 days as well as at a minimum 2-year follow-up. RESULTS: Overall, 248 patients undergoing DAIR for total hip arthroplasty or total knee arthroplasty PJI were included. Categorization of PJI was acute (acute postoperative) in 59 cases (24%), chronic in 54 (22%), and acute hematogenous in 135 (54%). DAIR survivorship was 47% (range 0.3-10 years). Overall, there were 118 (47.6%) treatment failures after DAIR with a minimum of 2-year follow-up. There was no difference in failure rate between total hip or total knee arthroplasty patients (P = .07). Patients infected with Staphylococcus conferred a higher risk of failure for all DAIR procedures regardless of chronicity category. CONCLUSION: Identification of microbial species prior to undertaking DAIR may be more clinically relevant than stratification according to chronicity category when considering treatment options.

Novel Use of Rifabutin and Rifapentine to Treat Methicillin-Resistant Staphylococcus aureus in a Rat Model of Foreign Body Osteomyelitis.

BACKGROUND: Owing to patient intolerance or drug interactions, alternative agents to rifampin are needed for management of staphylococcal periprosthetic joint infection. In the current study, we evaluated rifabutin, rifapentine and rifampin, with and without vancomycin, in a rat model of foreign body osteomyelitis. METHODS: Proximal tibiae were inoculated with methicillin-resistant Staphylococcus aureus (MRSA) and a Kirschner wire (K-wire) implanted in each. After 4 weeks of infection, rifampin, rifabutin, or rifapentine were administered, alone or with vancomycin. Tibiae and K-wires were cultured, and medians were reported as log10 colony-forming units (CFUs) per gram of bone or log10 CFUs per K-wire, respectively. RESULTS: Rifampin, rifabutin or rifapentine administered with vancomycin yielded less MRSA from bones (0.10, 3.02, and 0.10 log10 CFUs/g, respectively) than did no treatment (4.36 log10 CFUs/g) or vancomycin alone (4.64 log10 CFUs/g) (both P ≤ .02). The K-wires of animals receiving no treatment or vancomycin monotherapy recovered medians of 1.76 and 2.91 log10 CFUs/g per K-wire, respectively. In contrast, rifampin, rifabutin and rifapentine administered with vancomycin yielded medians of 0.1 log10 CFUs per K-wire, respectively. Rifampin resistance was detected in a single animal in the rifampin monotherapy group. CONCLUSIONS: Rifabutin or rifapentine with vancomycin were as active as rifampin with vancomycin against MRSA in rat foreign body osteomyelitis, suggesting that rifabutin and/or rifapentine may be alternatives to rifampin in the clinical management of staphylococcal periprosthetic joint infections.

Two-Stage Treatment for Total Knee Arthroplasty Infection Utilizing an Articulating Prefabricated Antibiotic Spacer.

Periprosthetic joint infection represents a serious complication following total knee arthroplasty. In the setting of chronic or age-indeterminate total knee arthroplasty infection, a 2-staged approach has been traditionally the preferred method of treatment over single-stage debridement and reimplantation debridement or debridement, antibiotics and implant retention. Two-stage is the preferred treatment method in North America and has demonstrated better overall success than the single stage techniques. Additionally, the 2-stage method is the preferred treatment for difficult to treat pathogens as well as in patients who have already undergone a previous revision procedure. An articulating prefabricated antibiotic spacer has entered the armamentarium of 2-stage revision knee surgery, and has demonstrated comparable results to custom and static spacers in terms of the primary goal of infection control. Importantly, the potential for enhanced mobility and function hold promise by safely providing a more "livable" knee during the convalescent period prior to definitive reimplantation.

Aseptic Reoperations Within 1 Year of Primary Total Knee Arthroplasty Markedly Increase the Risk of Later Periprosthetic Joint Infection.

BACKGROUND: Despite the high rate of success of primary total knee arthroplasty (TKA), some patients are candidates for early aseptic reoperation. The goal of this study is to evaluate the risk of subsequent periprosthetic joint infection (PJI) in patients treated with an aseptic reoperation within 1 year of primary TKA. METHODS: A retrospective review of our total joint registry compared 249 primary TKAs requiring an aseptic reoperation within 1 year following index arthroplasty to a control group of 17,867 TKAs not requiring reoperation within 1 year. Patients were divided into groups based on time from index TKA: (1) 90 days or less (114 TKAs) and (2) 91 to 365 days (135 TKAs). Mean age was 68 years with 57% female. Mean follow-up was 7 years. RESULTS: At 2 years postoperatively, patients undergoing an aseptic reoperation within 90 days subsequently had a 9% PJI rate, while patients undergoing an aseptic reoperation between 91 and 365 days subsequently had a 3% PJI rate. The control group had a 0.4% PJI rate. Compared to the control group, patients undergoing an aseptic reoperation within 90 days had an elevated risk of PJI (hazard ratio, 9; P < .0001), as did patients who had a reoperation between 91 and 365 days (hazard ratio, 4; P < .0001). CONCLUSION: Aseptic reoperation within 1 year of primary TKA was associated with a notably increased risk of subsequent PJI.

Alpha-defensin lateral flow test does not appear to be useful in predicting shoulder periprosthetic joint infections.

PURPOSE: Periprosthetic joint infections (PJIs) remain a challenging complication after shoulder arthroplasty. The antimicrobial peptide α-defensin has been proposed as a new synovial fluid biomarker in diagnosing PJIs. To date, only little data are available on the diagnostic accuracy of α-defensin in shoulder PJIs; thus, we aimed to evaluate its diagnostic value in a cohort of patients with a suspected shoulder PJI. METHODS: Between June 2016 and June 2018, we prospectively enrolled patients with a diagnostic shoulder aspiration due to painful shoulder arthroplasty or planned revision surgery. PJI diagnostics were performed according to the Musculoskeletal Infection Society (MSIS) criteria. All patients with an antibiotic therapy within two  weeks before enrollment, insufficient amount of synovial aspirate, or bloody aspiration were excluded. α-Defensin was measured in the synovial fluid using the α-defensin lateral flow (ADLF) test (Synovasure®). RESULTS: Out of 60 patients, we could include 29 (59% female) patients with a mean age of 70 (range, 50-92) years. A shoulder PJI was detected in five cases (Staphylococcus aureus, n = 2; Staphylococcus epidermidis, n = 2; Cutibacterium acnes, n = 1). The ADLF test was positive in seven out of 29 cases. According to the MSIS criteria, the ADLF test was false-negative in two patients and false-positive in four patients, resulting in sensitivity, specificity, and positive and negative predictive value of 60%, 83%, 43%, and 91%, respectively. The overall accuracy was 79%. CONCLUSION: The ALDF test does not appear to be useful in predicting shoulder PJIs but may be used as an additional diagnostic factor in rejecting these infections.