Periprosthetic joint infection: current concepts and outlook

Antimicrobial susceptibility testing of bone and joint pathogens using isothermal microcalorimetry

The rise in osteomyelitis and periprosthetic joint infections, in combination with increasing life expectancy and the prevalence of diabetes, underscores the urgent need for rapid and accurate diagnostic tools. Conventional culture-based methods are often time-consuming and prone to false-negatives, leading to prolonged and inappropriate antibiotic treatments. This study aims to improve osteomyelitis diagnostics by decreasing the time to detection and the time to an antibiotic susceptibility result to enable a targeted treatment using isothermal microcalorimetry (IMC). IMC measures heat flow in real-time, providing insights into bacterial metabolism without the need for labeling. Using clinical isolates from bone infections, assessing their response to antibiotics through IMC, we demonstrated that IMC could detect bacteria within 4 h and determine antimicrobial susceptibility profiles within 2-22 h (median 4.85, range 1.28-21.78). This is significantly faster than traditional methods. A decision tree, based on antibiotic susceptibility, accurately categorized pathogens, achieving high accuracy (74-100%), sensitivity (100%), and specificity (65-100%). These findings suggest that IMC could redefine diagnostics of bone and joint infections and potentially infections in general, offering timely and precise treatment guidance, thereby improving patient outcomes and reducing health care burdens. Further optimization and clinical validation are needed to fully integrate IMC into routine diagnostics.

Wireless implantable bioelectronics with a direct electron transfer lactate enzyme for detection of surgical site infection in orthopaedics

Periprosthetic infection is one of the most devastating complications following orthopaedic surgery. Rapid detection of an infection can change the treatment pathway and improve outcomes for the patient. In here, we propose a miniaturized lactate biosensor developed on a flexible substrate and integrated on a small-form bone implant to detect infection. The methods for lactate biosensor fabrication and integration on a bone implant are fully described within this study. The system performance was comprehensively electrochemically characterised, including with L-lactate solutions prepared in phosphate-buffered saline and culture medium, and interferents such as acetaminophen and ascorbic acid. A proof-of-concept demonstration was then conducted with ex vivo ovine femoral heads incubated with and without exposure to Staphylococcus epidermidis. The sensitivity, current density and limit-of-detection levels achieved by the biosensor were 1.25 μA mM-1, 1.51 μA.M-1.mm-2 and 66 μM, respectively. The system was insensitive to acetaminophen, while sensitivity to ascorbic acid was half that of the sensitivity to L-lactate. In the ex vivo bone model, S. epidermidis infection was detected within 5 h of implantation, while the control sample led to no change in the sensor readings. This pioneering work demonstrates a pathway to improving orthopaedic outcomes by enabling early infection diagnosis.

Progress in Designing Therapeutic Antimicrobial Hydrogels Targeting Implant-associated Infections: Paving the Way for a Sustainable Platform Applied to Biomedical Devices

Implantable biomedical devices have found widespread use in restoring lost functions or structures within the human body, but they face a significant challenge from microbial-related infections, which often lead to implant failure. In this context, antimicrobial hydrogels emerge as a promising strategy for treating implant-associated infections owing to their tunable physicochemical properties. However, the literature lacks a comprehensive analysis of antimicrobial hydrogels, encompassing their development, mechanisms, and effect on implant-associated infections, mainly in light of existing in vitro, in vivo, and clinical evidence. Thus, this review addresses the strategies employed by existing studies to tailor hydrogel properties to meet the specific needs of each application. Furthermore, this comprehensive review critically appraises the development of antimicrobial hydrogels, with a particular focus on solving infections related to metallic orthopedic or dental implants. Then, preclinical and clinical studies centering on providing quantitative microbiological results associated with the application of antimicrobial hydrogels are systematically summarized. Overall, antimicrobial hydrogels benefit from the tunable properties of polymers and hold promise as an effective strategy for the local treatment of implant-associated infections. However, future clinical investigations, grounded on robust evidence from in vitro and preclinical studies, are required to explore and validate new antimicrobial hydrogels for clinical use.

Non-tuberculous mycobacterial bone and joint infections - a case series from a tertiary referral centre in Australia

BACKGROUND

Non-tuberculous mycobacteria (NTM) are rare causes of bone and joint infection (BJI) and there is limited evidence on which to base management decisions. This study describes 1 year of experience from a multi-disciplinary BJI team which collects data on all cases reviewed at a tertiary referral centre in Queensland, Australia.

METHODS

The database was interrogated for all cases in which NTM were recovered from operative samples. Individual chart review was performed to collect the details of each case.

RESULTS

A total of seven cases were managed between 1st February 2021 and 28th February 2022, comprising one patient with chronic osteomyelitis, three with fracture-related infections, two with prosthetic joint infections, and one with infection of a synthetic ligament graft. In contrast to pulmonary NTM infections, most patients were clinically well and immunocompetent, and most infections were propagated by direct inoculation. Time to diagnosis was unknown in three patients, with 1, 2, 2, and 5 months for the remaining four. Rapid growing NTM were diagnosed on routine cultures and specific mycobacterial cultures were confirmatory. Management was characterized by multiple stage surgical procedures and prolonged antimicrobial regimens.

CONCLUSIONS

Antimicrobial complications were common; however, all patients were infection free at their latest follow up. Despite the inherent limitations, these results suggest that routinely ordering mycobacterial culture is of low yield. There is potential for shorter-term oral antimicrobial treatments. Prospective research is required to optimize treatment regimens and durations.

Construction and evaluation of a combined diagnostic model for chronic periprosthetic joint infection based on serological tests

BACKGROUND

Early diagnosis of chronic periprosthetic joint infection (CPJI) is crucial for ensuring effective treatment and improving patient outcomes. However, many auxiliary diagnostic tests are challenging to implement on a large scale due to economic and technical constraints, making CPJI diagnosis difficult. This study aims to design and validate a combined diagnostic model based on commonly used serological tests to evaluate its diagnostic value for CPJI and develop a diagnostic nomogram.

METHODS

A retrospective study from January 2019 to February 2024 involving 170 patients undergoing knee and hip arthroplasty revision for CPJI and aseptic loosening (AL) was conducted across two medical centers. These patients were divided into the training set and validation set. Patients were categorized into CPJI and AL groups based on infection status. Serological tests conducted upon admission were collected, and single-factor and multi-factor logistic regression analyses were used to identify independent diagnostic factors for early infection. These factors were integrated to construct a nomogram model. The model's performance was evaluated using the receiver operating characteristic area under the curve (AUC), Hosmer-Lemeshow test, decision curve analysis (DCA), and calibration curve, with external validation conducted on the validation set.

RESULTS

Multivariate logistic regression analysis showed that C-reactive protein (CRP), procalcitonin (PCT), and Platelet count/mean platelet volume ratio (PVR) were independent diagnostic factors for CPJI (p < 0.05). The AUCs for diagnosing CPJI using these individual factors were 0.806, 0.616, and 0.700 (p < 0.05), respectively, while their combined detection achieved an AUC of 0.861 (p < 0.05). The DCA clinical impact curve shows the combined model has good clinical utility when the threshold probability of infection presence is between 0.16 and 0.95. Similar results were obtained in the external validation cohort, with the combined detection having an AUC of 0.893.

CONCLUSION

The combined diagnostic model of CRP, PCT, and PVR significantly improves the The combined diagnostic model of CRP, PCT, and PVR significantly improves the diagnostic performance for CPJI compared to individual serum biomarkers. It exhibits good sensitivity, specificity, and clinical applicability, providing valuable references for CPJI diagnosis.

Incidence of periprosthetic joint infection after primary total knee arthroplasty shows significant variation : a synthesis of meta-analysis and bibliometric analysis

Total Knee Arthroplasty (TKA) is a surgery that is commonly performed on older adults to improve their quality of life. However, the increasing use of knee joint prostheses has led to a rise in the incidence of Prosthetic Joint Infections (PJI) in patients after TKA. Different clinical studies have looked at the occurrence of PJI after TKA in different regions, but they have drawn varying conclusions. To better understand this topic, we conducted a meta-analysis and bibliometric study using data from multiple databases. Our research found that the estimated prevalence of PJI after TKA is approximately 1.08% across different regions, but there is still considerable variation. Additionally, our regression analysis of sub-groups shows significant differences in follow-up periods. Furthermore, our comprehensive bibliometric analysis identifies current research trends, "hotspots" related to TKA-related PJI, influential nations, organizations, and noteworthy publications. Our analysis provides valuable insights to guide future research in this area.

Rifampin-resistant periprosthetic joint infections are associated with worse functional outcome in both acute and chronic infection types

Periprosthetic joint infections (PJI) pose a significant challenge in orthopaedic surgery, often requiring extensive surgical debridement and prolonged antibiotic treatment to eliminate the causative pathogens. Rifampin, known for its potent activity against biofilms, has been crucial in managing PJI by penetrating and disrupting these formations, thereby improving treatment efficacy. In this sense, antibiotic protocols lacking rifampin have shown increased failure rates. Consequently, the development of rifampin resistance could severely influence the prognosis of PJI. The aim of this clinical study was to assess how rifampin resistance affects the functional outcome in patients with PJI. In this single-centre comparative cohort study, we systematically documented all patients who presented with a PJI during the period spanning from 2018 to 2020. Two distinct groups were established for the study: Group 1 comprised 35 patients with a PJI caused by rifampin-susceptible pathogens and group 2 consisted of 28 patients with PJI caused by rifampin-resistant pathogens. A total of 63 patients (34 females) with a mean age of 68 years and a mean follow up of 37 months were included. The examination of patient-specific parameters did not reveal any identified risk factors as influential. Patients with a rifampin-resistant pathogen underwent a greater number of surgical revisions (6.9 ± 5.1 compared to 3.59 ± 3.39, p = 0.0011) and had extended durations of antibiotic treatment (p = 0.0052). The results of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score revealed significant differences in clinical outcome between both groups in every domain, even when stratified by acute and chronic entities. In total the WOMAC increased significantly from 21.57 ± 14.9 points in group 1 to 71.47 ± 62.7 points in group 2 (p < 0.001). The higher failure rates observed in group 2 were not statistically significant (p = 0.44). The current study demonstrates that PJI caused by rifampin-resistant bacteria are associated with a significantly worse functional outcome in both acute and chronic infection types without significantly affecting total failure rates.

Synovial fluid NMR-based metabolomics in septic and aseptic revision total knee arthroplasty: Implications on diagnosis and treatment

Periprosthetic joint infection (PJI) is one of the most challenging complications following total knee arthroplasty. Despite its importance, there is a paucity of reports in the literature regarding its pathogenesis. Recently, cellular metabolic reprogramming has been shown to play an important role in the progression and outcome of infectious diseases. Therefore, the aim of this study was to evaluate the metabolites composition of the synovial fluid from patients with PJI or aseptic failure of total knee arthroplasties. The synovial fluids from 21 patients scheduled for revision total knee arthroplasty (11 with the diagnosis of PJI and 10 with aseptic failures) were analyzed using 1D 1H NMR spectroscopy. Univariate and multivariate statistical analyzes were used to identify metabolites that were differentially abundant between those groups. A total of 28 metabolites were identified and five of them found to be differentially abundant between infected and non-infected synovial fluids. Lactate, acetate and 3-hydroxybutyrate were found to be in a higher concentration, and glucose and creatine were found reduced in the synovial fluid from PJI patients. Synovial fluid from patients with PJI exhibit a distinct metabolic profile, possibly reflecting metabolic adaptation that occurs in the infected periprosthetic microenvironment. Further research and studies are warranted to gain a broader insight into the metabolic pathways engaged by both pathogen and immune cells in the context of a 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.

Campylobacter coli Prosthetic Joint Infection: Case Report and a Review of the Literature

Prosthetic joint infections caused by Campylobacter are uncommon, with the majority of cases being attributed to C. fetus. This case report represents the third instance of a prosthetic hip infection caused by C. coli following an episode of gastroenteritis and, notably, in an immunocompetent patient. The infection was successfully managed by surgical debridement and lavage with retention of the prosthesis and 12 weeks of antibiotics. Furthermore, we present the first whole-genome sequence of a Campylobacter strain responsible for prosthetic joint infection and offer a comprehensive review of the literature on such infections.

Predictors of outcome following two-stage revision total knee arthroplasty

PURPOSE

Two stage revision arthroplasty remains the gold standard for peri-prosthetic joint infections of the knee. However, the functional outcomes of revision surgeries and the factors governing them require further investigation. The purpose of this study was to (a) evaluate impact of early and late stage I surgery and interval between stage I and stage II; (b) understand the impact of infecting organism and resistance; (c) to estimate long term survivorship and causes of failure.

METHODS

A retrospective review of 86 patients, who underwent two stage revision for prosthetic joint infections of the knee, was performed. Time between onset of symptoms to stage I (T1), and T1 to re-implantation (T2), along with microbiological studies, were analysed for their impact on functional outcomes, failure modalities and survivorship.

RESULTS

In this study, the mean KSS-Knee improved from 64.0 ± 10.0 pre-operatively to 76.9 ± 10.4, and 77.2 ± 10.1 at the 5 and 10 year follow up respectively. The KSS-Function improved from 44.4 ± 8.8 pre-operatively to 72.2 ± 9.5 and 79.8 ± 8.1 at 5 and 10 year follow-up respectively. This study also found that T1 and T2 remained critical factors in determining functional outcome and longevity of the implant and a delay in these intervals was a significant predictor of failure. Gram negative, poly-microbial infections and organisms with methicillin and vancomycin resistance demonstrated lower survivorship (p-value, 0.001 at 5, 10 and 12 years). Re-infections occurred in 4 cases while 9 cases failed due to aseptic causes.

CONCLUSION

Two-stage revision arthroplasty produced good functional outcomes when the infection was caused by single sensitive organism that did not exhibit high resistance to antibiotics. Stage I performed within 4 weeks and the subsequent re-implantation procedure undertaken within 6 weeks demonstrated better outcomes.

Mid- to long-term outcome of reverse total shoulder arthroplasty as revision procedure for failed hemiarthroplasty after proximal humerus fracture

BACKGROUND

Insufficient tuberosity healing is the most common reason for poor outcome after treatment of proximal humerus fractures (PHFs) using hemiarthroplasty (HA). In these cases, revision to reverse total shoulder arthroplasty (RTSA) can improve function and reduce pain in the short term, however, long-term results remain scarce. Aim of this study was to evaluate the clinical and radiological mid- to long-term results in patients with a revision RTSA after failed HA for PHF.

METHODS

In this retrospective study all patients that received a revision to RTSA after failed fracture HA between 2006 and 2018 were included. A total of 49 shoulders in 48 patients (38 female, 10 male; mean age 82 ± 9 years) were identified in our database. A total of 20 patients (17 female, 3 male; mean age was 79 ± 9 years) were available for follow-up examination after a mean time period of approximately eight years (3-14 years) after revision surgery. At final follow-up, patients were assessed using a subjective shoulder value (SSV), range of motion (ROM), visual analogue score (VAS), the Constant Score (CS) and the 12-Item Short Form Survey (SF-12).

RESULTS

At final follow-up, mean CS was 55 ± 19 (19-91), VAS averaged 3 ± 3 (0-8) and mean SSV was 61 ± 18% (18-90%). Mean SF-12 was 44 (28-57) with a mean physical component summary (PCS) of 38 (21-56) and a mean mental component summary (MCS) of 51 (29-67). On average active forward flexion (FF) was 104° (10-170°), active abduction (ABD) was 101° (50-170°), active external rotation (ER) was 19° (10-30°) and active internal rotation (IR) of the lumbosacral transition was reached. Three patients presented with a periprosthetic humeral fracture after RTSA implantation and underwent a reoperation (15%) during follow-up period.

CONCLUSIONS

Revision RTSA results in promising clinical results in patients after initial failed HA after PHF. A complication and reoperation rate of 15% is tolerable in consideration of satisfactory functional and psychological outcome.

TRIAL REGISTRATION

Retrospectively registered.

No shortening of the patellar tendon during two-stage total knee arthroplasty revision using articulating spacers

BACKGROUND

Surgical techniques in two-stage revision total knee arthroplasty (rTKA) include the use of articulating spacers and static spacers. Shortening of the patellar tendon could be a reason for inferior functional outcomes in two-stage septic rTKA . The aim of this study was to determine if articulating spacers also have negative effects on the extensor mechanism in rTKA.

METHODS

This retrospective study includes 65 consecutive patients (23 women, 42 men, age 71.3 ± 1.2; range, 51.2-88.6 years) undergoing septic two-stage rTKA using an articulating spacer between 2014 and 2021 in a single orthopedic center. For all patients, calibrated true lateral radiographs before total knee arthroplasty (TKA) explantation (T0), directly after TKA explantation (T1), shortly before TKA reimplantation (T2) and 6-8 days after TKA reimplantation (T3) were used to calculate the modified Insall Salvati ratio (mISR).

RESULTS

Overall, the mISR decreased significantly immediately after explantation (T0 vs. T1, p = 0.002) from 1.43 ± 0.03 to 1.36 ± 0.03 and remained stable until T2 (1.37 ± 0.02, p = 0.74). Following TKA reimplantation, the mISR increased again to 1.43 ± 0.03 (T3). There were no significant differences between T0 and T3 (p = 0.88). Six out of 65 patients (9%) experienced patellar tendon shortening > 10% at T3.

CONCLUSIONS

Septic two-stage revision TKA using an articulating spacer does not lead to patellar tendon shortening in the majority of cases. This study suggests that one reason for the improved range of motion after reimplantation may be the use of articulating spacers compared to static spacers.

Multifunctionally disordered TiO2 nanoneedles prevent periprosthetic infection and enhance osteointegration by killing bacteria and modulating the osteoimmune microenvironment

Rationale: Total hip arthroplasty (THA) and total knee arthroplasty (TKA) are effective interventions for end-stage osteoarthritis; however, periprosthetic infection is a devastating complication of arthroplasty. To safely prevent periprosthetic infection and enhance osteointegration, the surface modification strategy was utilized to kill bacteria, modulate the osteoimmune microenvironment, and improve new bone formation. Methods: We used the hydrothermal method to fabricate a bionic insect wing with the disordered titanium dioxide nanoneedle (TNN) coating. The mussel-inspired poly-dopamine (PDA) and antibacterial silver nanoparticles (AgNPs) were coated on TNN, named AgNPs-PDA@TNN, to improve the biocompatibility and long-lasting bactericidal capacity. The physicochemical properties of the engineered specimen were evaluated with SEM, AFM, XPS spectrum, and water contact assay. The biocompatibility, bactericidal ability, and the effects on macrophages and osteogenic differentiation were assessed with RT-qPCR, Western blotting, live/dead staining, immunofluorescent staining, etc. Results: The AgNPs-PDA@TNN were biocompatible with macrophages and exhibited immunomodulatory ability to promote M2 macrophage polarization. In addition, AgNPs-PDA@TNN ameliorated the cytotoxicity caused by AgNPs, promoted cell spreading, and increased osteogenesis and matrix deposition of BMSCs. Furthermore, AgNPs-PDA@TNN exhibited bactericidal ability against E. coli and S. aureus by the bionic nanostructure and coated AgNPs. Various imaging analyses indicated the enhanced bactericidal ability and improved new bone formation by AgNPs-PDA@TNN in vivo. H&E, Gram, and Masson staining, verified the improved bone formation, less inflammation, infection, and fibrosis encapsulation. The immunofluorescence staining confirmed the immunomodulatory ability of AgNPs-PDA@TNN in vivo. Conclusion: The bionic insect wing AgNPs-PDA@TNN coating exhibited bactericidal property, immunomodulatory ability, and enhanced osteointegration. Thus, this multidimensional bionic implant surface holds promise as a novel strategy to prevent periprosthetic infection.

Differences in Success Rate of Two-Stage Revision for Periprosthetic Joint Infection of the Knee Depending on the Applied Definition

BACKGROUND

Success rates of two-stage exchange arthroplasty are subject to substantial variance in the literature. An explanation is the lack of a universally accepted definition of what constitutes treatment success for periprosthetic joint infection. Therefore, the main objective of this study was to assess success rates, applying four definitions to identify the one definition that best captures "true" success from both a clinical and patient-centered perspective.

METHODS

This was a retrospective study investigating the outcome of a consecutive series of 78 chronic knee periprosthetic joint infections that were treated with a two-stage revision at a single center between 2017 and 2020. Kaplan-Meier survival analyses were conducted to estimate success rates.

RESULTS

After a mean follow-up of 36 months (range, 25 to 60), 64 patients (82%) were reimplanted after a mean interim period of 90 days (range, 22 to 201). There was one patient (1%) lost to follow-up, and the overall mortality was 15% (n = 12). Kaplan-Meier survival analyses were used to estimate treatment success at two and three years: implant survival was 93% (95% confidence interval [CI]: 82 to 97) and 87% (95% CI: 73 to 94), infection control was 90% (95% CI: 79 to 95) and 87% (95% CI: 73 to 93), success according to Delphi criteria was 88% (95% CI: 78 to 94), and success according to Musculoskeletal Infection Society criteria was 65% (95% CI: 53 to 74) at both timepoints.

CONCLUSIONS

Success rates were ranging between 65 and 93% depending on the applied definition, highlighting the need for universal success criteria. This variability mainly results from the differing approaches to patients who did not undergo reimplantation or passed away within a year of surgery. These patients exemplify cases of fatal treatment failures. Consequently, the Musculoskeletal Infection Society criteria should be routinely employed to accurately report the "true" success rate.

Staphylococcus capitis: insights into epidemiology, virulence, and antimicrobial resistance of a clinically relevant bacterial species

SUMMARYStaphylococcus capitis is divided into two subspecies, S. capitis subsp. ureolyticus (renamed urealyticus in 1992; ATCC 49326) and S. capitis subsp. capitis (ATCC 27840), and fits with the archetype of clinically relevant coagulase-negative staphylococci (CoNS). S. capitis is a commensal bacterium of the skin in humans, which must be considered an opportunistic pathogen of interest particularly as soon as it is identified in a clinically relevant specimen from an immunocompromised patient. Several studies have highlighted the potential determinants underlying S. capitis pathogenicity, resistance profiles, and virulence factors. In addition, mobile genetic element acquisitions and mutations contribute to S. capitis genome adaptation to its environment. Over the past decades, antibiotic resistance has been identified for S. capitis in almost all the families of the currently available antibiotics and is related to the emergence of multidrug-resistant clones of high clinical significance. The present review summarizes the current knowledge concerning the taxonomic position of S. capitis among staphylococci, the involvement of this species in human colonization and diseases, the virulence factors supporting its pathogenicity, and the phenotypic and genomic antimicrobial resistance profiles of this species.

Diagnosis and Treatment of Acute Periprosthetic Infections with the BioFire® System within a Time-Dependent and Bacterium-Dependent Protocol: Review and Prosthesis-Saving Protocol

Despite ongoing efforts to enhance diagnostic and treatment processes, the success rate for eradicating infections, particularly prosthetic joint infections (PJIs), currently stands at around 50%. For acute infections occurring shortly after arthroplasty, guidelines recommend a treatment known as DAIR (debridement, antibiotics, and implant retention). This approach is suggested for infections within 30 days post-arthroplasty or with less than 3 weeks of symptoms, provided that there is a stable implant and adequate soft-tissue mass. Several authors have suggested extending the use of DAIR beyond the initial 3-week period in specific cases. This extension practice seems increasingly feasible due to the rapid diagnostic capabilities offered by BioFire®. This technology allows for quick pathogen identification, aiding in the exclusion of cases that do not fit the criteria for the DAIR/DAPRI (debridement, antibiotic pearls and retention of the implant) protocol based on pathogen identification. The aim of this review is to re-examine the current literature on acute infections and present our proposed "prosthesis-saving" protocol, which integrates the BioFire® molecular diagnostic system. Continued research and assessment of the efficacy and safety of these protocols, especially regarding extended treatment timelines, are crucial for advancing the management of acute infections and enhancing outcomes for PJI patients.

First hip hemiarthroplasty in a Göttingen Minipig; surgical and post-mortem protocol

BACKGROUND

Prosthetic joint infections (PJI) are recalcitrant, hard-to-treat infections and severe complications of joint arthroplasty. Therefore, there is a need to develop new effective treatment strategies, and animal models of high clinical relevance are needed. This study aimed to develop a detailed surgical protocol for hip hemiarthroplasty in Göttingen minipigs and a thorough post-mortem sampling protocol to pave the way for creating a minipig PJI model.

METHODS

Three adult female Göttingen minipigs underwent surgery with insertion of a hip hemiarthroplasty, using the anterior approach to the hip joint. After surgery the minipigs were followed closely with daily clinical evaluation and gait scoring. Comprehensive post-mortem analyses were performed with evaluation of macroscopic lesions, microbiology, synovial fluid analysis and histology.

RESULTS

The study resulted in the first Göttingen minipig with hip hemiarthroplasty and identified several points of awareness when inserting a hip prosthesis in minipigs, especially the high risk of joint dislocation. A spontaneous PJI occurred in one of the minipigs, revealing an impaired ability of the immune cells to reach the bacteria at the bone-prosthesis interface.

CONCLUSION

The present study provides a detailed description of surgical technique and post-mortem sampling and validates the suitability of the hip hemiarthroplasty minipig model for future experimental modeling of PJI.

Debridement, antibiotics and implant retention (DAIR) following hip and knee arthroplasty: results and findings of a multidisciplinary approach from a non-specialist prosthetic infection centre

INTRODUCTION

Prosthetic joint infection (PJI) is a catastrophic complication following arthroplasty surgery. Recently a debridement, antibiotics and implant retention (DAIR) procedure has gained popularity for PJI where a thorough debridement, irrigation and modular component exchange is undertaken.

METHOD

We present the outcome for DAIR, data collected prospectively, in a busy orthopaedic unit but not one specialising in PJI. All patients with PJI were included without loss of data or patients from 2012 to 2018 with a minimum follow-up of 5 years.

RESULTS

Four total knee replacements, 17 total hip replacements, one revision total hip replacement and three hip hemiarthroplasties are included with an average duration from onset of symptoms to the DAIR procedure of 11 days (range 1-22 days). Staphylococcus aureus (24%) and Staphylococcus epidermidis (32%) were the most common causative organisms, and the most common antibiotic regimens included intravenous teicoplanin and flucloxacillin. Average follow-up was 67 months (range 9-104 months). Only four patients went on to require revision surgery. An analysis of midterm patient outcome measures for 6 of the total hip replacement (THR) DAIR patients were compared with a database of 792 THRs (with a minimum two-year follow-up) carried out by the same surgeon revealed no significant difference in Oxford hip scores at one-year post-surgery (OHS DAIR 36.2 vs 39 for control group).

CONCLUSION

This study includes 25 consecutive patients treated with DAIR with only one reinfection, with a mean follow-up period of 5 years. Using a strict protocol, DAIR appears to offer a successful treatment strategy for the management of early 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.

Hydrogen-treated CoCrMo alloy: a novel approach to enhance biocompatibility and mitigate inflammation in orthopedic implants

In recent decades, orthopedic implants have been widely used as materials to replace human bone tissue functions. Among these, metal implants play a crucial role. Metals with better chemical stability, such as stainless steel, titanium alloys, and cobalt-chromium-molybdenum (CoCrMo) alloy, are commonly used for long-term applications. However, good chemical stability can result in poor tissue integration between the tissue and the implant, leading to potential inflammation risks. This study creates hydrogenated CoCrMo (H-CoCrMo) surfaces, which have shown promise as anti-inflammatory orthopedic implants. Using the electrochemical cathodic hydrogen-charging method, the surface of the CoCrMo alloy was hydrogenated, resulting in improved biocompatibility, reduced free radicals, and an anti-inflammatory response. Hydrogen diffusion to a depth of approximately 106 ± 27 nm on the surface facilitated these effects. This hydrogen-rich surface demonstrated a reduction of 85.2% in free radicals, enhanced hydrophilicity as evidenced by a decrease in a contact angle from 83.5 ± 1.9° to 52.4 ± 2.2°, and an increase of 11.4% in hydroxyapatite deposition surface coverage. The cell study results revealed a suppression of osteosarcoma cell activity to 50.8 ± 2.9%. Finally, the in vivo test suggested the promotion of new bone formation and a reduced inflammatory response. These findings suggest that electrochemical hydrogen charging can effectively modify CoCrMo surfaces, offering a potential solution for improving orthopedic implant outcomes through anti-inflammatory mechanisms.

In vitro evaluation of microbial D- and L-lactate production as biomarkers of infection

Mammalian cells produce and metabolize almost exclusively L-lactate, bacterial species have the capacity to produce both D-lactate and L-lactate. The aim of this study was to evaluate the intrinsic production of D- and L-lactate in the most common pathogenic microorganisms causing septic arthritis (SA) and periprosthetic joint infection (PJI) as a potential biomarker for the diagnosis of infection. Following microorganisms were grown according to ATCC culture guides and tested for production of D- and L-lactate: Staphylococcus aureus (ATCC 43300), Staphylococcus epidermidis (ATCC 35984), Enterococcus faecalis (ATCC 19433), Streptococcus pyogenes (ATCC 19615), Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), Cutibacterium acnes (ATCC 11827), and Candida albicans (ATCC 90028). Pathogens were inoculated in 8 ml of appropriate liquid media and incubated as planktonic or biofilm form in either aerobic, anaerobic or CO2 atmosphere up to 312 h. D- and L-lactate measurements were performed at different time points: 0, 6, 9, 12 and 24 h, then once per day for slow-growing pathogens. Samples were serially diluted and plated for colony counting. Liquid culture media without microorganisms served as a negative control. Production of D-lactate was observed in all tested microorganisms, whereas no L-lactate was detected in E. coli, P. aeruginosa, and C. albicans. Maximal concentration of D-lactate was produced by S. aureus (10.99 mmol/L), followed by E. coli (1.22 mmol/L), and S. epidermidis (0.48 mmol/L). Maximal L-lactate concentration was observed in S. pyogenes (10.12 mmol/L), followed by S. aureus (9.71 mmol/L), E. faecalis (2.64 mmol/L), and S. epidermidis (2.50 mmol/L). S. epidermidis bacterial biofilm produced significantly higher amount of D- and L-lactate compared to planktonic form (p = 0.015 and p = 0.002, respectively). Our study has demonstrated that the most common pathogenic microorganisms causing SA and PJI have the capability to generate measurable amounts of D-lactate in both planktonic and biofilm form, highlighting the practical value of this biomarker as an indicator for bacterial and fungal infections. In contrast to D-lactate, the absence of L-lactate production in certain tested bacteria, as well as in fungi, suggests that L-lactate is not eligible as a biomarker for diagnosing microbial infections.

Genetic and Modifiable Risk Factors for Postoperative Complications of Total Joint Arthroplasty: A Genome-Wide Association and Mendelian Randomization Study

Background: Total joint arthroplasty (TJA) is an orthopedic procedure commonly used to treat damaged joints. Despite the efficacy of TJA, postoperative complications, including aseptic prosthesis loosening and infections, are common. Moreover, the effects of individual genetic susceptibility and modifiable risk factors on these complications are unclear. This study analyzed these effects to enhance patient prognosis and postoperative management. Methods: We conducted an extensive genome-wide association study (GWAS) and Mendelian randomization (MR) study using UK Biobank data. The cohort included 2964 patients with mechanical complications post-TJA, 957 with periprosthetic joint infection (PJI), and a control group of 398,708 individuals. Genetic loci associated with postoperative complications were identified by a GWAS analysis, and the causal relationships of 11 modifiable risk factors with complications were assessed using MR. Results: The GWAS analysis identified nine loci associated with post-TJA complications. Two loci near the PPP1R3B and RBM26 genes were significantly linked to mechanical complications and PJI, respectively. The MR analysis demonstrated that body mass index was positively associated with the risk of mechanical complications (odds ratio [OR]: 1.42; p < 0.001). Higher educational attainment was associated with a decreased risk of mechanical complications (OR: 0.55; p < 0.001) and PJI (OR: 0.43; p = 0.001). Type 2 diabetes was suggestively associated with mechanical complications (OR, 1.18, p = 0.02), and hypertension was suggestively associated with PJI (OR, 1.41, p = 0.008). Other lifestyle factors, including smoking and alcohol consumption, were not causally related to postoperative complications. Conclusions: The genetic loci near PPP1R3B and RBM26 influenced the risk of post-TJA mechanical complications and infections, respectively. The effects of genetic and modifiable risk factors, including body mass index and educational attainment, underscore the need to perform personalized preoperative assessments and the postoperative management of surgical patients. These results indicate that integrating genetic screening and lifestyle interventions into patient care can improve the outcomes of TJA and patient quality of life.

Enhancing Outcomes in Prosthetic Joint Infections: The Significance of the Periprosthetic Joint Infection Tumor, Node, and Metastasis (PJI-TNM) Classification and Biodegradable Antibiotic Beads

BACKGROUND AND OBJECTIVES

Periprosthetic joint infections (PJIs) that occur after hip and knee arthroplasty have a major influence on patient outcomes and healthcare expenses. This study assesses the effectiveness of the PJI tumor, node, and metastasis (PJI-TNM) categorization system and the latest developments in local antibiotic delivery methods for the treatment of PJIs.

MATERIALS AND METHODS

The study involved a retrospective analysis of 23 patients who received treatment for septic hip or knee prostheses at the SUUB Orthopedics and Traumatology Clinic between January 1, 2022, and February 10, 2024. Approval was gained following ethical considerations. Patients were categorized using the PJI-TNM system, and their therapy was customized based on the severity of the infection. The surgical procedures involved either one-stage or two-stage revisions, utilizing vancomycin and gentamicin antibiotic-loaded calcium sulfate beads to administer antibiotics locally. Data pertaining to demographics, clinical characteristics, and microbiology were gathered and examined.

RESULTS

The study comprised 14 male and 9 female patients, with an average age of 68 years. The presence of chronic infections was mostly seen, indicating the development of mature biofilm. Prevalent coexisting medical conditions included diabetes, obesity, and heart failure. The duration of infection control measures was, on average, six months, and 65% of patients reported experiencing enhanced mobility. Acute infections with positive antibiotic responses underwent one-stage modifications. For the majority of patients, a treatment approach involving two-stage modifications, which includes the use of antibiotic-loaded spacers followed by the installation of a prosthesis, proved to be beneficial.

CONCLUSIONS

The PJI-TNM classification system improves the management of PJI by offering a systematic method for customized therapy. Calcium sulfate beads, which are biodegradable carriers for antibiotics, provide notable advantages, especially for individuals with severe comorbidities. Continuous progress in diagnostic techniques and localized administration of antibiotics is essential for enhancing the therapy of PJI and improving patient outcomes.

Serum albumin-to-globulin ratio and CRP-to-albumin ratio did not outperform serum CRP in diagnosing periprosthetic joint infections

Aims

Serum inflammatory parameters are widely used to aid in diagnosing a periprosthetic joint infection (PJI). Due to their limited performances in the literature, novel and more accurate biomarkers are needed. Serum albumin-to-globulin ratio (AGR) and serum CRP-to-albumin ratio (CAR) have previously been proposed as potential new parameters, but results were mixed. The aim of this study was to assess the diagnostic accuracy of AGR and CAR in diagnosing PJI and to compare them to the established and widely used marker CRP.

Methods

From 2015 to 2022, a consecutive series of 275 cases of revision total hip (n = 129) and knee arthroplasty (n = 146) were included in this retrospective cohort study. Based on the 2021 European Bone and Joint Infection Society (EBJIS) definition, 144 arthroplasties were classified as septic. Using receiver operating characteristic curve (ROC) analysis, the ideal thresholds and diagnostic performances were calculated. The areas under the curve (AUCs) were compared using the z-test.

Results

AGR, CAR, and CRP were associated with PJI (p < 0.001). Sensitivities were 62.5% (95% CI 54.3 to 70.0), 73.6% (95% CI 65.8 to 80.1), and 71.5% (95% CI 63.6 to 78.3), respectively. Specificities were calculated with 84.7% (95% CI 77.5 to 89.9), 86.3% (95% CI 79.2 to 91.2), and 87.8% (95% CI 80.9 to 92.4), respectively. The AUC of CRP (0.797 (95% CI 0.750 to 0.843)) was significantly higher than the AUC of AGR (0.736 (95% CI 0.686 to 0.786), p < 0.001), and similar to AUC of CAR (0.799 (95% CI 0.753 to 0.846), p = 0.832). Decreased sensitivities were observed in PJIs caused by low-virulence organisms (AGR: 60%, CAR: 78%) compared to high-virulence pathogens (AGR: 80%, p = 0.042; CAR: 88%, p = 0.158). Higher sensitivities were seen in acute haematogenous (AGR: 83%, CAR: 96%) compared to chronic PJIs (AGR: 54%, p = 0.001; CAR: 65%, p < 0.001).

Conclusion

Serum AGR and CAR showed limited diagnostic accuracy (especially in low-grade and chronic infections) and did not outperform the established marker CRP in our study. Hence, neither parameter can be recommended as an additional tool for diagnosing PJI.

Advancements in treatment strategies for periprosthetic joint infections: A comprehensive review

Periprosthetic joint infection (PJI) presents a critical challenge in orthopedic care, contributing to significant patient morbidity and healthcare costs. This burden is expected to increase secondary to growing demand for total joint arthroplasty (TJA). Despite the profound significance of PJI, there is currently no universally accepted "gold standard" diagnostic criteria using serum biomarker thresholds; latest criteria fail to differentiate acute infections from chronic or consider time since initial surgery. Furthermore, contemporary PJI treatment, which conventionally requires 2-stage revision surgery in conjunction with rigorous antibiotic treatment, can be particularly taxing on patients. Fortunately, recent years have seen marked evolution in both PJI diagnosis and treatment methods. Contemporary research supports time-dependent serum biomarker thresholds with greater sensitivity and specificity than previously reported, as well as alternative surgical options which may be more suitable for certain patients. The following narrative review aims to describe the significance and pathogenesis of PJI before characterizing current challenges, novel innovations, and the future landscape of PJI diagnosis and management. Here, we spotlight the emerging utility of novel biomarkers and metagenomic next-generation sequencing for diagnosis, advancements in patient-centered surgical outcome prediction tools for PJI risk assessment and prevention, and evolving surgical techniques including 1-stage and a "hybrid" 1.5-stage revision surgeries. Additionally, we explore cutting-edge therapeutic modalities including peptide and bacteriophage-based treatments, intraoperative anti-biofilm gel, the VT-X7 antibiotic pump, and promising immune-based interventions. Ultimately, these advancements hold the potential to revolutionize PJI management, offering hope for improved outcomes and reduced burdens on healthcare systems.

Antiseptics' Concentration, Combination, and Exposure Time on Bacterial and Fungal Biofilm Eradication

Background

This study aims to assess the activity of solutions containing povidone-iodine (PI) and hydrogen peroxide (H2O2) alone or combined on the biofilm of microbial species in the contest of periprosthetic joint infection (PJI).

Methods

Different antiseptic solutions were tested on 2-day-old biofilms of Gram-positive and Gram-negative bacteria and fungi at 1 and 3 minutes of exposure. The efficacy of these solutions was evaluated by measuring the biofilm metabolic activity by methoxynitrosulfophenyl-tetrazolium carboxanilide (XTT) reduction assay. The anti-biofilm effect of 5% PI and 0.3% PI + 0.5% H2O2 was tested on a 5-day-old biofilm using colony-forming unit counts and an XTT reduction assay.

Results

PI and H2O2 solutions showed concentration-dependent anti-biofilm activity except for E. faecalis. PI at 5% was the most active solution against the 2-day-old biofilm of all test microorganisms. The 0.3% PI + 0.5% H₂O₂ solution had a significant effect only at 3 minutes. The 5% PI and 0.3% PI + 0.5% H₂O₂ effect was evaluated on 5-day-old biofilms. PI at 5% produced a significant reduction in metabolic activity at both 1 and 3 minutes; 0.3% PI + 0.5% H₂O₂ caused a significant activity against all Gram-positive strains after 3 minutes, with a greater metabolic activity reduction than 5% PI.

Conclusions

In the case of PJI caused by Gram-positive bacteria, 0.3% PI + 0.5% H₂O₂ could be used for wound irrigation for 3 minutes of exposure. In the case of PJI with a different etiological agent or PJI with an unknown etiology, it is advisable to use 5% PI for 1 minute of exposure.

Periprosthetic hip infection: Current concepts and the Wrightington experience

Total hip arthroplasty (THA) is a highly successful operation performed worldwide in increasing numbers for a wide range of indications. There has been a corresponding rise in the incidence of periprosthetic joint infection of the hip (PJIH), which is a devastating complication. There is a significant variation in the definition, diagnosis and management of PJIH largely due to a lack of high-level evidence. The current standard of practice is largely based on cohort studies from high-volume centres, consensus publications amongst subject experts, and national guidance. This review describes our philosophy and practical approach of managing PJIH at a regional tertiary high-volume joint replacement centre.

Insight into antibacterial effect of titanium nanotubular surfaces with focus on Staphylococcus aureus and Pseudomonas aeruginosa

Materials used for orthopedic implants should not only have physical properties close to those of bones, durability and biocompatibility, but should also exhibit a sufficient degree of antibacterial functionality. Due to its excellent properties, titanium is still a widely used material for production of orthopedic implants, but the unmodified material exhibits poor antibacterial activity. In this work, the physicochemical characteristics, such as chemical composition, crystallinity, wettability, roughness, and release of Ti ions of the titanium surface modified with nanotubular layers were analyzed and its antibacterial activity against two biofilm-forming bacterial strains responsible for prosthetic joint infection (Staphylococcus aureus and Pseudomonas aeruginosa) was investigated. Electrochemical anodization (anodic oxidation) was used to prepare two types of nanotubular arrays with nanotubes differing in dimensions (with diameters of 73 and 118 nm and lengths of 572 and 343 nm, respectively). These two surface types showed similar chemistry, crystallinity, and surface energy. The surface with smaller nanotube diameter (TNT-73) but larger values of roughness parameters was more effective against S. aureus. For P. aeruginosa the sample with a larger nanotube diameter (TNT-118) had better antibacterial effect with proven cell lysis. Antibacterial properties of titanium nanotubular surfaces with potential in implantology, which in our previous work demonstrated a positive effect on the behavior of human gingival fibroblasts, were investigated in terms of surface parameters. The interplay between nanotube diameter and roughness appeared critical for the bacterial fate on nanotubular surfaces. The relationship of nanotube diameter, values of roughness parameters, and other surface properties to bacterial behavior is discussed in detail. The study is believed to shed more light on how nanotubular surface parameters and their interplay affect antibacterial activity.

The treatment of bacterial biofilms cultivated on knee arthroplasty implants using the bioelectric effect

Introduction: The formation of bacterial biofilms on knee arthroplasty implants can have catastrophic consequences. The aim of this study was to analyze the effectiveness of the bioelectric effect in the elimination of bacterial biofilms on cultivated knee arthroplasty implants. Methods: A novel device was designed to deliver a bioelectric effect on the surface of knee arthroplasty implants. 4-femoral prosthetic implants were cultivated with a staphylococcus aureus inoculum for 15 days. The components were divided into four different groups: A (not treated), B (normal saline 20-minutes), C (bioelectric effect 10-minutes), D (bioelectric effect 20-minutes). The implants were sonicated, and the detached colonies were quantified as the number of colony-forming unit (CFUs). The implants were sterilised and the process was repeated in a standardized manner four more times, to obtain a total of five samples per group. Results: The number of the CFUs after a 10-minute exposure to the bioelectric effect was of 208.2 ± 240.4, compared with 6,041.6 ± 2010.7 CFUs in group A, representing a decrease of 96.5% ± 4.3 (p = 0.004). And a diminution of 91.8% ± 7.9 compared with 2,051.0 ± 1,364.0 CFUs in group B (p = 0.109). The number of bacterial colonies after a 20-minute exposure to the bioelectric effect was 70 ± 126.7 CFUs, representing a decrease of 98.9% ± 1.9 (p = 0.000) compared with group A. And a decrease of 97.8% ± 3.0 (p = 0.019) compared with group B. Conclusions: The bioelectric effect was effective in the elimination of bacterial biofilm from knee arthroplasty implants. This method could be used in the future as part of conventional surgical procedures.

Synthesis and preclinical evaluation of novel 18F-vancomycin-based tracers for the detection of bacterial infections using positron emission tomography

INTRODUCTION

Bacterial infections are a major problem in medicine, and the rapid and accurate detection of such infections is essential for optimal patient outcome. Bacterial infections can be diagnosed by nuclear imaging, but most currently available modalities are unable to discriminate infection from sterile inflammation. Bacteria-targeted positron emission tomography (PET) tracers have the potential to overcome this hurdle. In the present study, we compared three 18F-labelled PET tracers based on the clinically applied antibiotic vancomycin for targeted imaging of Gram-positive bacteria.

METHODS

[18F]FB-NHS and [18F]BODIPY-FL-NHS were conjugated to vancomycin. The resulting conjugates, together with our previously developed [18F]PQ-VE1-vancomycin, were tested for stability, lipophilicity, selective binding to Gram-positive bacteria, antimicrobial activity and biodistribution. For the first time, the pharmacokinetic properties of all three tracers were compared in healthy animals to identify potential binding sites.

RESULTS

[18F]FB-vancomycin, [18F]BODIPY-FL-vancomycin, and [18F]PQ-VE1-vancomycin were successfully synthesized with radiochemical yields of 11.7%, 2.6%, and 0.8%, respectively. [18F]FB-vancomycin exhibited poor in vitro and in vivo stability and, accordingly, no bacterial binding. In contrast, [18F]BODIPY-FL-vancomycin and [18F]PQ-VE1-vancomycin showed strong and specific binding to Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA), which was outcompeted by unlabeled vancomycin only at concentrations exceeding clinically relevant vancomycin blood levels. Biodistribution showed renal clearance of [18F]PQ-VE1-vancomycin and [18F]BODIPY-FL-vancomycin with low non-specific accumulation in muscles, fat and bones.

CONCLUSION

Here we present the synthesis and first evaluation of the vancomycin-based PET tracers [18F]BODIPY-FL-vancomycin and [18F]PQ-VE1-vancomycin for image-guided detection of Gram-positive bacteria. Our study paves the way towards real-time bacteria-targeted diagnosis of soft tissue and implant-associated infections that are oftentimes caused by Gram-positive bacteria, even after prophylactic treatment with vancomycin.

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.

Do urinary tract infections affect the rate of periprosthetic joint infections in patients who underwent arthroplasty surgery? A systematic review and meta-analysis

Periprosthetic joint infection (PJI) is a significant issue in orthopedic surgery. Urinary tract infections (UTIs) and asymptomatic bacteriuria (ASB) have been identified as potential causes of PJI; however, evidence is inconclusive. Understanding these relationships is critical for improving therapy and patient outcomes. A systematic review was performed by conducting searches from PubMed, EBSCO, ProQuest, and manual searching with adherence to the Preferred Reporting Items for Systematic Review and Meta-Analysis 2020 guideline. Studies that reported UTI/ASB and PJI were included. Meta-analysis was conducted using a random-effects model using RevMan 5.4 software. A total of 14 studies were included with UTIs and ASB showed an overall association with increased risk of PJI (odds ratio [OR]: 1.84, 95% confidence interval [CI]: 1.14-2.99, P = 0.01). However, subgroup analysis for UTIs and ASB was not significant. Further analysis of UTIs in total hip arthroplasty (THA) surgery showed a significant association (OR: 1.76, 95% CI: 1.57-1.96) with PJI. Preoperative UTIs timing between 0 and 2 weeks before surgery showed an increased risk of PJI (OR: 1.45, 95% CI: 1.35-1.55). Antibiotic treatment in ASB did not significantly impact PJI rates. Urine and PJI sample cultures in four studies showed no correlation of microorganisms between the two sites. According to recent evidence, a statistically significant association was found between UTIs and PJI in patients who underwent THA surgery. However, ASB did not yield significant results in relation to PJI. These results should be supported by larger and well-designed studies to make proper clinical suggestion in future. For further research, it is recommended to adopt standardized criteria for outcome measurement and to involve larger sample sizes to enhance the reliability and generalizability of findings.

Complications of antibiotic cement spacers used for elbow infections

BACKGROUND

Antibiotic cement spacers have been widely used in the treatment of joint infections. There are no commercially available antibiotic spacers for the elbow. Instead, they are typically fashioned by the surgeon at the time of surgery using cement alone or a combination of cement with sutures, Steinmann pins, external fixator components, or elbow arthroplasty components. There is no consensus regarding the ideal elbow antibiotic spacer and no previous studies have examined the complications associated with these handmade implants in relation to their unique structural design.

METHODS

We retrospectively reviewed 55 patients who had 78 static antibiotic cement spacers implanted between January 1998 and February 2021 as part of a 2-stage treatment plan for infection of an elbow arthroplasty, other elbow surgery, or primary elbow infection. Several antibiotic spacer structures were used during the study period. For analysis purposes, the spacers were classified into linked and unlinked spacers based on whether there was a linking mechanism between the humerus and the ulna. Complications related to these spacers that occurred either during the implantation, between implantation and removal, or during removal were recorded and analyzed from chart review and follow-up x rays. Reoperations due to spacer-related complications were also recorded.

RESULTS

Among the 55 patients (78 spacers), there were 23 complications, including 17 minor and 6 major complications. The most common complication of unlinked spacers (intramedullary [IM] dowels, beads and cap spacer) was spacer displacement. Other complications included IM dowel fracture and difficulty locating beads during spacer removal. The major complications of linked cement spacers included two periprosthetic humerus fractures after internal external fixator cement spacers and re-operation due to breakage and displacement of one bushing cement spacer. The major complications of unlinked cement spacers included two reoperations due to IM dowel displacement and one reoperation due to displacement of beads. Among patients who had removal of all components and those with native joints, there was no statistically significant difference between internal external fixator cement spacers and unlinked cement spacers in minor complication rates (30% vs. 16%, P = .16), major complication rates (7% vs. 8%, P = .85) and reoperation rates (0% vs. 8%, P = .12).

CONCLUSIONS

Static handmade antibiotic elbow spacers have unique complications related to their structural designs. The most common complication of linked and nonlinked cement spacers were failure of the linking mechanism and displacement, respectively. Surgeons should keep in mind the possible complications of different structures of cement spacers when choosing 1 antibiotic spacer structure over another.

Diagnostic Performance of a Molecular Assay in Synovial Fluid Targeting Dominant Prosthetic Joint Infection Pathogens

Prosthetic joint infection (PJI) is one of the most serious complications of joint replacement surgery among orthopedic surgeries and occurs in 1 to 2% of primary surgeries. Additionally, the cause of PJIs is mostly bacteria from the Staphylococcus species, accounting for more than 98%, while fungi cause PJIs in only 1 to 2% of cases and can be difficult to manage. The current gold-standard microbiological method of culturing synovial fluid is time-consuming and produces false-negative and -positive results. This study aimed to identify a novel, accurate, and convenient molecular diagnostic method. The DreamDX primer-hydrolysis probe set was designed for the pan-bacterial and pan-fungal detection of DNA from pathogens that cause PJIs. The sensitivity and specificity of DreamDX primer-hydrolysis probes were 88.89% (95% CI, 56.50-99.43%) and 97.62% (95% CI, 87.68-99.88%), respectively, compared with the microbiological method of culturing synovial fluid, and receiver operating characteristic (ROC) area under the curve (AUC) was 0.9974 (*** p < 0.0001). It could be concluded that the DreamDX primer-hydrolysis probes have outstanding potential as a molecular diagnostic method for identifying the causative agents of PJIs, and that host inflammatory markers are useful as adjuvants in the diagnosis of PJIs.

Modern Microbiological Methods to Detect Biofilm Formation in Orthopedy and Suggestions for Antibiotic Therapy, with Particular Emphasis on Prosthetic Joint Infection (PJI)

Biofilm formation is a serious problem that relatively often causes complications in orthopedic surgery. Biofilm-forming pathogens invade implanted foreign bodies and surrounding tissues. Such a condition, if not limited at the appropriate time, often requires reoperation. This can be partially prevented by selecting an appropriate prosthesis material that prevents the development of biofilm. There are many modern techniques available to detect the formed biofilm. By applying them we can identify and visualize biofilm-forming microorganisms. The most common etiological factors associated with biofilms in orthopedics are: Staphylococcus aureus, coagulase-negative Staphylococci (CoNS), and Enterococcus spp., whereas Gram-negative bacilli and Candida spp. also deserve attention. It seems crucial, for therapeutic success, to eradicate the microorganisms able to form biofilm after the implantation of endoprostheses. Planning the effective targeted antimicrobial treatment of postoperative infections requires accurate identification of the microorganism responsible for the complications of the procedure. The modern microbiological testing techniques described in this article show the diagnostic options that can be followed to enable the implementation of effective treatment.

A Simple and Cost-Effective FeCl3-Catalyzed Functionalization of Cellulose Nanofibrils: Toward Adhesive Nanocomposite Materials for Medical Implants

In the present work, we explored Lewis acid catalysis, via FeCl3, for the heterogeneous surface functionalization of cellulose nanofibrils (CNFs). This approach, characterized by its simplicity and efficiency, facilitates the amidation of nonactivated carboxylic acids in carboxymethylated cellulose nanofibrils (c-CNF). Following the optimization of reaction conditions, we successfully introduced amine-containing polymers, such as polyethylenimine and Jeffamine, onto nanofibers. This introduction significantly enhanced the physicochemical properties of the CNF-based materials, resulting in improved characteristics such as adhesiveness and thermal stability. Reaction mechanistic investigations suggested that endocyclic oxygen of cellulose finely stabilizes the transition state required for further functionalization. Notably, a nanocomposite, containing CNF and a branched low molecular weight polyethylenimine (CNF-PEI 800), was synthesized using the catalytic reaction. The composite CNF-PEI 800 was thoroughly characterized having in mind its potential application as coating biomaterial for medical implants. The resulting CNF-PEI 800 hydrogel exhibits adhesive properties, which complement the established antibacterial qualities of polyethylenimine. Furthermore, CNF-PEI 800 demonstrates its ability to support the proliferation and differentiation of primary human osteoblasts over a period of 7 days.

Coblation Versus Surgical Debridement Against MRSA Infection in Wounds With Shrapnel: A Preliminary Study

INTRODUCTION

Debridement plays a critical role in wound management. In addition to removing necrotic tissue, debridement can eliminate bacteria frequently harbored within the tissue. This study evaluated a novel debridement method that uses plasma-based radiofrequency technology to remove tissue and bacteria. Coblation is a technology that uses radiofrequency energy to excite the electrolytes in a conductive medium, such as saline, to create a precisely focused plasma. This plasma field contains highly energized particles that possess sufficient energy to break tissue molecular bonds, causing the tissue to dissolve at relatively low temperatures (typically 40 °C to 70 °C).

MATERIALS AND METHODS

Eighteen deep dermal wounds measuring 22 mm × 22 mm × 3 mm deep were created on pigs. Wounds were inoculated with methicillin-resistant Staphylococcus aureus USA300 (MRSA USA300) in combination with shrapnel and then covered with a polyurethane dressing for 24 hours. Wounds were then randomly assigned to one of the 3 treatment groups: (1) Coblation, (2) surgical debridement, and (3) no debridement. Wounds were biopsied on days 0, 5, 9, and 12, and specimens were processed for MRSA counts using selective media. Statistical analysis was performed using IBM SPSS statistics 27 using one-way ANOVA.

RESULTS

Comparison between coblation and surgical debridement showed a decrease in bacterial count in all assessment times. The lowest bacterial count in all assessment times was observed in wounds debrided with coblation showing a statistically significant (P ≤ .05) decrease in more than 2 Log CFU/g on days 0, 5, and 9 compared to no debridement. On day 12, coblation-debrided wounds exhibited 6.10 ± 0.22 Log CFU/g, and this value represents 99.99% of reduction compared with non-debrided wounds (P ≤ .05). More than 96% of reduction (P ≤ .05) resulted in wounds treated with coblation compared with surgically debrided.

CONCLUSIONS

Reducing MRSA bacterial infection counts, especially of biofilm-associated organisms, in combination with shrapnel may have important clinical implications, especially for the military personnel. Further research into the use of this technology in wound management is warranted.

Do High Doses of Multiple Antibiotics Loaded into Bone Cement Spacers Improve the Success Rate in Staphylococcal Periprosthetic Joint Infection When Rifampicin Cannot Be Employed?

Rifampicin is one of the mainstays in treating staphylococcal prosthetic joint infection (PJI). However, discontinuation due to intolerance, drug interactions, and adverse events is common. Two-stage revision surgery remains the gold standard, with the number of revision arthroplasties steadily increasing. This study aims to evaluate the effectiveness and safety of a novel two-stage revision protocol for staphylococcal prosthetic joint infection (PJI) utilizing bone cement spacers loaded with multiple high doses of antibiotics. Additionally, it seeks to analyze outcomes in patients ineligible for rifampicin treatment. A retrospective review of 43 cases of staphylococcal hip and knee prosthetic joint infections (PJIs) from 2012 to 2020 was conducted. In all instances, a commercial cement containing 1 g of gentamicin and 1 g of clindamycin, augmented with 4 g of vancomycin and 2 g of ceftazidime, was employed to cast a spacer manually after thorough surgical debridement. We report an eradication rate of 82%, with no significant differences observed (p = 0.673) between patients treated with (84%, n = 19) and without rifampicin (79%, n = 24). There were no disparities in positive culture rates (7%), spacer replacement (18%), or survival analysis (p = 0.514) after an average follow-up of 68 months (range 10-147) in the absence of systemic toxicity and surgical complications superimposable to those previously reported. In conclusion, two-stage revision with local high doses of ceftazidime, vancomycin, gentamicin, and clindamycin demonstrates high effectiveness in treating staphylococcal PJIs. Notably, systemic rifampicin does not influence the outcomes. This protocol, with multiple high doses of antibiotics loaded into the bone cement spacer, is presented as a viable and safe alternative for patients unsuitable for rifampicin treatment.

Active myeloperoxidase: a promising biomarker to differentiate "acute" and "low-grade" peri-prosthetic joint infections from aseptic failures

Introduction

The accurate distinction between periprosthetic joint infections (PJI) and aseptic failures (AF) is of paramount importance due to differences in treatment. However, this could be challenging by using the current criteria. Various synovial fluid biomarkers are being assessed to improve the diagnostic accuracy. Myeloperoxidase (MPO), an enzyme contained in the granules of neutrophils, may be a promising biomarker for PJI.

Methods

Synovial fluids of 99 patients (n = 65 PJI according to EBJIS criteria; n = 34 AF) were collected in two specialized orthopedic centers. PJI were divided into acute (n = 33) and low-grade (n = 32) according to previously published classification. An activity assay specific for active MPO was performed in each sample. Ability of MPO to correctly discriminate patients with PJI from AF was determined by ROC analysis. The best discriminating cut-off value was determined by calculating the J Youden index. For all analyses, a P value < 0.05 was considered statistically significant.

Results

Active MPO was higher in PJI than AF (P < 0.0001). The ROC analysis revealed a significant area under the curve (AUC: 0.86; 95% CI: 0.78-0.93, P < 0.0001). A cut-off value of 561.9 U/mL, with good sensitivity (0.69) and specificity (0.88), discriminated between AF and PJI (accuracy 75.76%, 95% CI: 66.11-83.81%, positive likelihood ratio 5.88, 95% CI: 2.31-14.98 and negative likelihood ratio 0.35, 95%CI: 0.24-0.51). No difference in MPO levels was found between acute and chronic low-grade PJI.

Conclusion

The proposed assay appears to be a reliable and affordable tool for detecting the active MPO in synovial fluid, with promising characteristics of sensitivity and specificity in discriminating both acute and low-grade PJI from AF. Further studies are needed to confirm MPO diagnostic cut-off values and validate their use in the routine clinical practice.

KLIC Score Does Not Predict Failure After Early Prosthetic Joint Infection: An External Validation With 153 Knees and 130 Hips

BACKGROUND

A preoperative risk score, the KLIC score (chronic renal failure [K], liver cirrhosis [L], indication of the index surgery [I], cemented prosthesis [C], and C-reactive protein >115 mg/L), has been developed to predict the risk of treatment failure after early prosthetic joint infection (PJI). This study aimed to validate the KLIC score for the debridement, antibiotics, and implant retention (DAIR) procedure and one-stage revisions in a Northern European cohort.

METHODS

Revisions due to early PJI of the hip or knee between January 1, 2008, and September 12, 2021, were identified retrospectively. The primary outcome was early failure, which was considered when the patient needed an unscheduled surgery, the patient died, or the patient was prescribed long-term suppressive antibiotics. To examine the association between KLIC score and failure risk, univariable logistic regression with area under the curve (AUC) was used. In addition, models were calibrated to assess prognostic ability and clinical utility was examined with decision-curve analyses.

RESULTS

An increase in KLIC score had a moderate predictive value for early failure after DAIR (odds ratio [OR] 1.45; confidence interval [CI] 1.13 to 1.90). For one-stage revision, it was only slightly predictive of failure (OR 1.20; CI 0.93 to 1.56). After 60 days, the AUC for DAIR was 0.63 (CI 0.55 to 0.72) and 0.56 (CI 0.46 to 0.66) for one-stage revisions, indicating poor discriminative ability. The decision-curve analyses revealed that the model did not offer a remarkable net benefit across a range of threshold probabilities.

CONCLUSIONS

We demonstrated that the KLIC score is not a reliable predictor of early failure after early PJI in a Northern European cohort. Using the model to guide treatment decisions does not provide any additional clinical utility beyond the baseline strategies.

Retrospective analysis of a flucloxacillin oral absorption test in patients requiring flucloxacillin therapy: results and determination of factors associated with adequate absorption

OBJECTIVES

Flucloxacillin has the most narrow spectrum to treat staphylococcal infections, but has a large variability in bioavailability which hampers its intravenous (iv) to oral switch. To identify patients with adequate absorption, the use of an oral absorption test (OAT) measuring total plasma concentrations of flucloxacillin before and after an oral dose of 1 gram flucloxacillin, was previously published. The current pilot study aims to evaluate the fraction of patients with adequate absorption using a similar OAT; to assess the therapeutic consequences and to identify potential factors associated with adequate absorption.

METHODS

Demographic data of adult patients treated with iv flucloxacillin and requiring prolonged therapy were collected retrospectively between May 2020 and November 2021 at Ghent University Hospital. A previously published OAT protocol was used, with addition of a protocol for intermittent dosing of iv flucloxacillin. Adequate absorption was defined as an increase in plasma concentration of at least 10 mg/L.

RESULTS

The flucloxacillin OAT was performed in 99 patients, of which 62% were men, with a median age of 58 years and 95% received intermittent dosing of iv flucloxacillin. Of the 99 patients, 55% had a result indicating an adequate absorption and 49% of all patients were switched to oral flucloxacillin afterwards. Inadequate absorption was found to be associated with higher Body Mass Index and higher flucloxacillin baseline concentration, while co-administration of acetylsalicylic acid was associated with an adequate absorption.

CONCLUSIONS

Based on the OAT, 49% of all patients were switched to oral flucloxacillin instead of broader-spectrum anti-staphylococcal antibiotics. This implicates that an OAT could be a valuable antimicrobial stewardship measure by restricting the use of broad-spectrum antibiotics. For each of the associations found, a hypothesis was formulated about the underlying reason or mechanism; these should be confirmed in future studies with prospective and multicentric design.

The influence of gut microbiome on periprosthetic joint infections: State-of-the art

Early periprosthetic joint infection constitutes one of the most frightening complications of joint replacement. Recently, some evidence has highlighted the potential link between dysregulation of the gut microbiota and degenerative diseases of joints. It has been hypothesized that microbiome dysbiosis may increase the risk of periprosthetic joint infection by facilitating bacterial translocation from these sites to the bloodstream or by impairing local or systemic immune responses. Although the processes tying the gut microbiome to infection susceptibility are still unknown, new research suggests that the presurgical gut microbiota-a previously unconsidered component-may influence the patient's ability to resist infection. Exploring the potential impact of the microbiome on periprosthetic joint infections may therefore bring new insights into the pathogenesis and therapy of these disorders. For a successful therapy, a proper surgical procedure in conjunction with an antibacterial concept is essential. As per the surgical approach, different treatment strategies include surgical irrigation, debridement, antibiotic therapy, and implant retention with or without polyethylene exchange. Other alternatives could be one-stage or two-stage revisions surgery. Interventions that either directly target gut microbes as well as interventions that modify the composition and/or function of the commensal microbes represent an innovative and potentially successful field to be explored. In recent times, innovative therapeutic methods have arisen in the realm of microbiome restoration and the management of gut-related ailments. These progressive approaches offer fresh perspectives on tackling intricate microbial imbalances in the gastrointestinal tract. These emerging therapies signify a shift towards more precise and individualized approaches to microbiome restoration and the management of gut-related disorders. Once a more advanced knowledge of the pathways linking the gut microbiota to musculoskeletal tissues is gained, relevant microbiome-based therapies can be developed. If dysbiosis is proven to be a significant contributor, developing treatments for dysbiosis may represent a new frontier in the prevention of periprosthetic joint infections.

Investigation of the pathogen-specific antibody response in periprosthetic joint infection

PURPOSE

Periprosthetic joint infections (PJIs) are a very demanding complication of arthroplasty. Diagnosis of PJI and pathogen identification pose considerable challenges in clinical practice. We hypothesized that the pathogen-specific immune response to PJI reflects the infection process, provides clinically relevant information on disease course, and has the potential to further optimize antimicrobial therapy.

METHODS

We conducted a prospective matched cohort pilot study with 13 patients undergoing two-stage septic revision arthroplasty (PJI patients) between 06/2020 and 06/2021, as well as 11 control patients undergoing one-stage aseptic revision arthroplasty (Non-PJI patients). Pre-, intra- and postoperative serum samples were collected at standardized time points. We developed a custom Luminex®-based quantitative bead-based suspension array (Infection Array; IA), and used it for simultaneous measurement of antibody specificities against 32 pathogens commonly associated with PJI in 267 serum samples.

RESULTS

The IA was able to trace the dynamics of the pathogen-specific humoral immune response in all patients against PJI-related pathogens, prominently coagulase-negative staphylococci and streptococci. Pathogen-specific serum antibody titers declined in 62% of PJI patients over the course of treatment, while no changes in antibody titers were observed in 82% of Non-PJI patients during this study. Our serological data strongly suggested that antibody signatures reflect an immune response to microbial invasion.

CONCLUSION

Our results provide insights into the pathophysiology of PJI and information on the individual disease courses. The IA is therefore a promising and novel serological tool of high resolution for monitoring the immunoproteomic footprints of infectious pathogens in the course of PJI.

Mouldable Collagen-Tricalciumphosphate Is a Safe Carrier for Local Antibiotics-Short-Term Results in Revision Hip Arthroplasty

BACKGROUND

Improving local antibiotic delivery is a promising approach to improve infection control and potentially shorten systemic treatment in periprosthetic joint infection (PJI). This study investigates the use of an antibiotic-loaded, mouldable collagen-tricalciumphosphate composite in treatment of hip PJI.

METHODS

124 application cases in 79 patients were included from a referral centre; systemic adverse infects, local complications, and infection control were analysed.

RESULTS

In most cases, either vancomycin or meropenem were used. Pathogens were previously known in 82 (66%) cases with polymicrobial infection in 20 (25%) patients. There were no cases of hypercalcaemia. Acute kidney injure was present in 14 (11%) cases. Chronic kidney failure persisted in two cases. During a mean follow-up of 12 (SD 9.3; range 3-35) months, implant survival was achieved in 73 (92%) patients; revision due to PJI was performed in 19 cases.

CONCLUSION

Mouldable collagen-tricalciumphosphate composite bone substitute as a local antibiotic carrier in revision hip arthroplasty appears to be a valid option for local antibiotic delivery without systemic complications. Implant survival of 92% supports the hypothesis that local antibiotic therapy is an important component in the treatment of PJI.

Risk factors for peri-megaprosthetic joint infections in tumor surgery: A systematic review

BACKGROUND

Peri-megaprosthetic joint infections (PJI) in tumor surgery are complex and challenging complications that significantly impact the outcomes of the patients. The occurrence of PJI poses a substantial threat to the success of these operations. This review aims to identify and summarize the risk factors associated with PJI in tumor surgery with megaprosthetic reconstruction as well as to determine the overall risk of PJI in limb salvage surgery.

METHODS

A thorough examination of published literature, scrutinizing the incidence of PJI in tumor prostheses after limb salvage surgery was done. Research studies that documented the incidence of PJI in tumor patients who underwent limb salvage surgery, and explored the risk factors associated with the occurrence of PJI were deemed eligible.

RESULTS

A total of 15 studies were included in the analysis and underwent comprehensive examination. After the exploration of key parameters, several significant risk factors for PJI concerning the type of implant coating, surgical site characteristics, patient demographics, and procedural factors were recorded.

DISCUSSION

The findings underscore the need for a nuanced approach in managing tumor patients undergoing limb salvage surgery and megaprosthetic reconstruction, with emphasis on individualized risk assessments and individualized preventive strategies.

Implementation of Outpatient Parenteral Antimicrobial Therapy (OPAT) in Patients with Complicated Periprosthetic Joint Infections

Periprosthetic joint infections (PJI) are a serious complication of arthroplasty with high morbidity. With growing bacterial resistance and limited disposability of oral antibiotics with sufficient bioavailability, the need for intravenous antibiotic application is raising. This causes long-term hospital stays and rising costs. In the course of transferring procedures into an outpatient setting as well as coping with pressures on hospital capacity, outpatient parenteral antimicrobial therapy (OPAT) can build a bridge for the treatment of such infections.In a single centre analysis, 47 cases treated with OPAT were studied in relation to pathogen, antimicrobial resistance, indication for OPAT and follow up. Furthermore, the patients received an anonymised questionnaire with 4 clusters of interest in terms of internal quality assessment on the success and evaluation of this therapeutic procedure. Special attention was paid to the descriptive analysis of patients with periprosthetic joint infections (n = 30).Between May 2021 and October 2022 out of 47 patients with OPAT, 30 cases with periprosthetic joint infections were identified. For infected hip- and knee arthroplasties, a remarkable spectrum of pathogens was found. In hip infections highly resistant strains of Staphylococcus epidermidis and Enterococci were detected. In knee infections, the pathogens were more susceptible, but however highly virulent Staphylococcus aureus and Streptococci. Difficult to treat, mixed infections were found in both locations. The indication for OPAT was based in half of the cases on the high level of antimicrobial resistance, with availability of only parenteral applicable antibiotics. Further indications were mixed infections and difficult to treat pathogens, with flucloxacillin therapy as well as OPAT as the last therapeutic option. The questionnaire showed 96% patient satisfaction in terms of organisation and acceptance of this kind of therapy. Complications or unexpected outpatient/ hospital treatments were very rare in connection with OPAT. Two thirds of patients reported completion of the treatment. In the clinical follow up (average of 5.7 months), 96.6% of cases were declared free of infection. In one patient the infection persisted.OPAT is a safe and reliable therapeutic option for outpatients to continue parenteral antimicrobial treatment in joint infections. Due to increasing pressure on hospitals in terms of costs and capacity, this therapy offers an alternative to inpatient treatment. The indication for OPAT should be set individually, risk adjusted and not generalised for all patients. The outpatient sector needs financial and structural support for comprehensive roll-out of this treatment in Germany. A further focus should be on the prevention of periprosthetic joint infections. With the knowledge of the expected pathogens and the surgical resources, the standards should be adapted. The choice of the antibiotic should be specified and the intervals of application be shortened, according to the surgical course, in order to yield high levels of agent concentration in the surgical area. Further investigations are required to test the superiority of OPAT versus the oral administration of antibiotics in long-term observations as well as to define the necessary duration of OPAT.

Impact of a Novel Antiseptic Lavage Solution on Acute Periprosthetic Joint Infection in Hip and Knee Arthroplasty

Background: Periprosthetic joint infection (PJI) represents a challenge following hip or knee arthroplasty, demanding immediate intervention to prevent implant failure and systemic issues. Bacterial biofilm development on orthopedic devices worsens PJI severity, resulting in recurrent hospitalizations and significant economic burdens. The objective of this retrospective cohort study is to evaluate the efficacy of this novel antiseptic solution, never previously evaluated in vivo, in managing early post-operative or acute hematogenous PJI following primary hip and knee joint replacements. Methods: The inclusion criteria consist of patients with total hip arthroplasty (THA) or knee arthroplasty diagnosed with acute PJI through preoperative and intraoperative investigations, in accordance with the MSIS ICM 2018 criteria. The minimum required follow-up was 12 months from the cessation of antibiotic therapy. This novel antiseptic lavage solution is composed of ethanol, acetic acid, sodium acetate, benzalkonium chloride and water. Data included demographic characteristics, diagnostic criteria, surgical techniques, post-operative treatment and follow-up outcomes. Results: A total of 39 patients treated with Debridement, Antibiotics Pearls and Retention of the Implant (DAPRI) procedures using this solution between May 2021 and April 2023 were analyzed. At a mean follow-up of 24.6 ± 6.4 months, infection recurrence-free survival rates were 87.2%, with no local allergic reactions or relevant systemic adverse effects detected. Persistent PJI necessitated two-stage revision surgery. Conclusions: This novel antiseptic lavage solution shows promise as an adjunctive tool in the treatment of PJI, demonstrating support in infection control while maintaining a favorable safety profile.

Biofilm on total joint replacement materials can be reduced through electromagnetic induction heating using a portable device

BACKGROUND

Periprosthetic joint infection is a serious complication following joint replacement. The development of bacterial biofilms bestows antibiotic resistance and restricts treatment via implant retention surgery. Electromagnetic induction heating is a novel technique for antibacterial treatment of metallic surfaces that has demonstrated in-vitro efficacy. Previous studies have always employed stationary, non-portable devices. This study aims to assess the in-vitro efficacy of induction-heating disinfection of metallic surfaces using a new Portable Disinfection System based on Induction Heating.

METHODS

Mature biofilms of three bacterial species: S. epidermidis ATCC 35,984, S. aureus ATCC 25,923, E. coli ATCC 25,922, were grown on 18 × 2 mm cylindrical coupons of Titanium-Aluminium-Vanadium (Ti6Al4V) or Cobalt-chromium-molybdenum (CoCrMo) alloys. Study intervention was induction-heating of the coupon surface up to 70ºC for 210s, performed using the Portable Disinfection System (PDSIH). Temperature was monitored using thermographic imaging. For each bacterial strain and each metallic alloy, experiments and controls were conducted in triplicate. Bacterial load was quantified through scraping and drop plate techniques. Data were evaluated using non-parametric Mann-Whitney U test for 2 group comparison. Statistical significance was fixed at p ≤ 0.05.

RESULTS

All bacterial strains showed a statistically significant reduction of CFU per surface area in both materials. Bacterial load reduction amounted to 0.507 and 0.602 Log10 CFU/mL for S. aureus on Ti6Al4V and CoCrMo respectively, 5.937 and 3.500 Log10 CFU/mL for E. coli, and 1.222 and 0.372 Log10 CFU/mL for S. epidermidis.

CONCLUSIONS

Electromagnetic induction heating using PDSIH is efficacious to reduce mature biofilms of S aureus, E coli and S epidermidis growing on metallic surfaces of Ti6Al4V and CoCrMo alloys.

Is there sufficient evidence to support the use of antibiotic holiday just before the second stage of an infected total hip or knee arthroplasty revision surgery?

The practice of implementing an antibiotic holiday before the second stage of hip or knee arthroplasty is currently controversial due to limited evidence for this approach, as per the International Consensus Meeting 2018 on Musculoskeletal Infection. A greater understanding of this issue could augment the quality of Alrayes and Sukeik's mini-review (2023) on diagnosing, managing, and treating periprosthetic knee infections. However, a significant lack of literature exists concerning the optimal duration for the antibiotic holiday, calling for more research before establishing any clinical guidelines.