Journal of Bone and Joint Infection最新文献

Introduction: Fasciocutaneous and muscle flaps are used for the reconstruction of lower-limb composite bone and soft-tissue defects. Flap-mediated contributions to the healing microenvironment are less described. We present a comparative porcine model with a standardized bone and soft-tissue defect reconstructed by fasciocutaneous or muscle flaps and characterize the early tissue response following flap transfer. Methods: Using both hindlimbs of 10 female pigs, symmetrical tibial bone and soft-tissue defects were created and reconstructed with fasciocutaneous flaps ( $n=$ 8) or muscle flaps ( $n=$ 8) or were closed primarily ( $n=$ 4, controls). Interstitial metabolites (glucose, lactate, and pyruvate) were sampled by microdialysis from flap and control tissue for 11 h before, during, and after 60 min of global flap ischemia (simulating free flap transfer). Flap histopathology was graded for the acute inflammatory response. Results: All pigs and flaps completed the study. Both flaps exhibited ischemia-reperfusion-induced metabolic alterations relative to the control tissue. The lactate-to-pyruvate ratio increased 3-fold in muscle flaps during ischemia, while fasciocutaneous flaps showed lactate and a lactate-to-pyruvate ratio that were 1.5-fold higher during reperfusion. Histopathology demonstrated early cellular activity at the bone lesion-flap interface in both flap types, with greater oedema and hyperaemia in fasciocutaneous flaps. Conclusion: We established a reproducible comparative large-animal model integrating interstitial metabolite and histopathological analyses to describe early flap-mediated tissue responses. Early flap-specific differences in metabolic and structural patterns may influence flap function and the healing microenvironment. The model provides a basis for evaluating clinically relevant ortho-plastic outcomes.

Periprosthetic joint infections (PJIs), particularly those caused by multidrug-resistant organisms (MDROs), remain a major therapeutic challenge. Antimicrobial blue light (ABL) offers a promising non-antibiotic approach, inducing bacterial killing through photoexcitation of endogenous chromophores and subsequent reactive oxygen species generation. However, conventional single-point illumination systems are limited by uneven light distribution and poor penetration, restricting their use to superficial infections. We evaluated a novel isotropic optical fiber designed to overcome these geometric and optical constraints. The fiber was tested against vancomycin-resistant Enterococcus faecium (VR-Ef) and carbapenemase-producing Klebsiella pneumoniae (CP-Kp) in time-to-kill assays under low-power (20.1 mW mm^-1) and high-power (40.3 mW mm^-1) conditions over 60 min. Bacterial counts (CFU per mL) were determined at 0, 10, 20, 30, and 60 min. A one-way analysis of variance (ANOVA) with Tukey's post hoc test assessed time-dependent reductions; a two-way ANOVA evaluated the combined effects of illumination power and exposure time. ABL exposure resulted in time- and intensity-dependent bacterial reduction in both strains. Significant CFU reductions occurred from 30 min onward under high-power ABL (HP-ABL) and after 60 min under low-power ABL (LP-ABL) for both VR-Ef and CP-Kp ( $p<0.001$ ). The two-way ANOVA revealed significant main and interaction effects of illumination power and exposure time (all $p<0.001$ ). Although bactericidal thresholds ( $\ge 3{\log }_{10}$  reduction) were not reached, bacterial killing increased markedly with higher power and longer exposure. This novel isotropic optical fiber enables uniform intraluminal ABL delivery, potentially extending blue-light therapy from superficial to deep surgical infections such as PJIs. Further optimization of illumination parameters and potential integration with photosensitizers may enhance its antimicrobial efficacy and clinical applicability.

Introduction: Pubic bone osteomyelitis (PBO) is a rare complication with sometimes delayed development in patients who have received radiotherapy or surgery of the pelvic region for cancer treatment. Treatment options range from antibiotics alone to pubic bone debridement and source control via diversion of gastrointestinal (GI) or genitourinary (GU) tract fistulae. In this single-center case series of patients with cancer, we sought to characterize outcomes of PBO. Methods: We conducted a retrospective analysis of 26 patients, admitted for PBO to Memorial Sloan Kettering Cancer Center between 2017 and 2024. Demographic, clinical presentation, microbiology, treatment, and outcome data were evaluated. Patients were followed until date of death or date of last follow-up. Results: Of the 26 patients, 23 were male (88 %) and 3 were female (12 %), with a median age at diagnosis of 70.5 years. The median follow-up period was 680 d. 18/26 (69 %) had fistulas to the pubic bone. 15 patients (58 %) received antibiotics alone. 11 patients (42 %) underwent pubic bone debridement; 8 underwent additional GI or GU diversion procedures for source control. In the group who received surgery, 9/11 (81 %) were ambulating without assistive devices at end of follow-up. In those receiving antibiotics alone, 9/15 (60 %) died a median of 466 d from diagnosis of PBO. Conclusion: In our case series, a combination of surgical debridement plus targeted antibiotic therapy offered the best outcomes. However, some patients achieved improvement in symptoms with antibiotic management alone when more aggressive surgical interventions were not feasible.

Background: Implant-associated infections remain a major challenge in orthopaedic surgery. This study aimed to evaluate the anti-adherent and anti-biofilm properties of a novel anodized 316L stainless-steel (A 316L SS) surface against common pathogens in osteosynthesis-associated infections (OAIs). Methods: Bacterial adherence and biofilm formation of Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, Cutibacterium acnes, Escherichia coli, and Pseudomonas aeruginosa were assessed on A 316L SS and non-anodized 316L stainless steel (Ref 316L SS). Adherence was evaluated after 90 min using fluorescence microscopy. Biofilm development was examined after 24-48 h in synthetic synovial fluid (SSF) using colony counts and scanning electron microscopy (SEM). Results: A 316L SS significantly reduced bacterial adherence and surface coverage for all species tested compared to Ref 316L SS. In biofilm assays, A 316L SS exhibited notable anti-biofilm properties, with significantly reduced biofilm formation for all species. E. faecalis and C. acnes also showed lower planktonic bacterial counts. Imaging confirmed decreased bacterial presence and extracellular matrix on A 316L SS. Conclusions: A 316L SS shows strong anti-adherent and anti-biofilm properties against common orthopaedic pathogens, even under in vivo-like conditions. This surface modification strategy holds significant potential for reducing implant-associated infections and warrants further investigation for clinical applications.

Background: Culture-negative periprosthetic joint infections (CN-PJIs) remain a major problem in the field of orthopedic infections. The clinical features of CN-PJI and its risk factors remain poorly defined. The purpose of this study was to elucidate the characteristics of CN-PJI. Methods: This was a retrospective multi-center cohort study as part of the Orthopaedic Device Infection Network (ODIN). Using real-world data from five institutions across Australia, the Netherlands and the USA, 563 cases of PJI (470 culture positive, 93 culture negative) were queried between 1995 and 2021. Patients with CN-PJI had negative cultures on pre-operative aspiration, blood or intra-operative cultures. Demographics, history of surgery on the infected joint, presenting symptoms, operative details, laboratory values and intra-operative findings were recorded. Multivariable regression was used to determine the association between these variables and culture negativity. Results: The prevalence of CN-PJI was 16.5 %. Bivariate analysis revealed that patients with CN-PJI were more likely to be female, have a revision arthroplasty or prior PJI, have a longer duration of symptoms and were less likely to present with fever, wound dehiscence or wound necrosis; they also had lower hemoglobin and serum CRP ( $p$ $<$ $0.05$ for all). Using multivariable regression, the only factor significantly associated with CN-PJI was a duration of symptoms of $>$ 12 weeks (OR 2.24, 95 % CI 1.008-4.964, $p$ $=$ $0.048$ ). Conclusions: Patients with prolonged symptoms were twice as likely to have negative cultures, supporting the traditional belief that CN-PJI presents more insidiously. These clinical data should be used to guide the selection of advanced investigations.

Background and purpose: Periprosthetic joint infection (PJI) revisions for total knee arthroplasty (TKA) and total hip arthroplasty (THA) have increased all-cause mortality. It remains unclear whether specific causes of death contribute to this excess mortality. Our purpose was to compare the underlying causes of death in patients revised for PJI with aseptic failure and to compare THA and TKA causes of death. Methods: We used routinely collected data from Danish health registries. We identified 9078 patients undergoing first-time revision for PJI or aseptic failure in the Danish Hip and Knee Arthroplasty Register. PJI was primarily defined by intra-operative microbiological cultures. The causes of death were obtained from the Cause of Death Register. We used inverse probability of treatment weighting (IPTW) to adjust for confounding and calculated adjusted hazard ratios (aHRs) with a 95 % confidence interval (CI). Among 2755 deceased patients, 37 % had undergone revision for PJI and 63 % for aseptic failure. The PJI group had a higher comorbidity burden and more hip revisions but was similar in age and marital status compared to aseptic revisions. Results: Cancer, circulatory, and respiratory diseases were the most common causes of death in both groups. However, deaths from musculoskeletal diseases (aHR 3.04, 95 % CI: 1.67-5.56), infections (aHR 2.13, 95 % CI: 1.06-4.30), and age-related causes (aHR 2.05, 95 % CI: 1.22-3.45) were more frequent after PJI revision. Conclusion: The increased mortality after PJI revision appears to be multifactorial, involving a range of causes rather than a single dominant driver.

Introduction: Infection remains a major complication of open fractures, with rates reaching up to 70 % after severe injury. Systemic antibiotics often fail to achieve the therapeutic levels needed to disrupt biofilm at the wound site due to compromised blood flow and systemic dilution. This study investigates the efficacy of systemic antibiotics against Staphylococcus aureus and Pseudomonas aeruginosa monomicrobial biofilms in an ovine model of simulated fracture-related infection (FRI). Methods: An established model of long-bone FRI in the right hind limb of mature Rambouillet sheep was adapted. Local soft tissue trauma was induced, the periosteum was stripped from the tibial surface, and a simulated fracture was created on the bone surface. The site was inoculated with mature biofilm grown on fracture fixation plates. Sheep were assigned to a treatment group receiving 10 d of systemic antibiotic therapy or a positive control group that received no treatment. All animals were sacrificed at 21 d, and microbiological and histological analysis was performed. Results: Systemic antibiotics failed to produce a statistically significant reduction in S. aureus biofilm compared to the positive control. Systemic therapy significantly reduced P. aeruginosa bioburden compared to the positive control, but levels remained above the clinical threshold for infection. The histological analysis revealed moderate improvement from systemic treatment. Conclusions: This investigation established the limitations of systemic antibiotic therapy in this model of long-bone FRI against S. aureus and P. aeruginosa biofilms. Microbiological and histological analyses revealed hallmark features of recalcitrance to systemic treatment, validating the utility of this model to study anti-infective therapies. These findings highlight the need for new antibiotic delivery strategies to manage biofilm-associated infections.

Purpose: Periprosthetic joint infection (PJI) represents a major complication of total joint arthroplasty (TJA). The joint-specific bone involvement, antimicrobial options, coverage of the soft tissues, and host status (JS-BACH) classification of 2021 aims to categorize PJI severity and predict PJI recurrence and quality of life following surgical PJI treatment. Until now, only one external validation has confirmed its predictive value for treatment failure. This study aimed to further validate the classification in an external cohort and to compare outcomes between different pathogen groups. Methods: We applied the JS-BACH classification to a cohort of 249 consecutive gram-positive (staphylococci) and gram-negative PJIs in hip and knee joints treated at our institution between 2010 and 2022 (Staphylococcus aureus $n=62$ ; coagulase-negative staphylococci $n=115$ ; gram-negative organisms $n=72$ ). According to the JS-BACH classification, we divided cases into uncomplicated ( $n=35$ ), complex ( $n=155$ ), and limited options ( $n=59$ ). The median (interquartile range, IQR) follow-up was 25.0 (3-59) and at least 12 months. Outcomes were assessed based on the 2013 Delphi consensus on PJI outcome. PJI was defined following the EBJIS classification. Results: A higher JS-BACH category correlated significantly with a lower infection-free survival. Using uncomplicated cases as baseline, the hazards ratio (HR) was 3.2 (95 %-CI 1.3-7.9) for complex and 6.6 (95 %-CI 2.6-16.7) for limited options cases. Similarly, higher JS-BACH categories were associated with lower revision-free survival for recurrent PJI, again with uncomplicated cases as baseline: complex HR 2.2 (95 %-CI 0.9-5.5); limited options HR 4.1 (95 %-CI 1.6-10.8). The mean infection-free survival was 85.7 %, 58.7 %, and 33.9 % for uncomplicated, complex, and limited options cases ( $p<0.001$ ). Conclusion: The novel JS-BACH classification provides reliable predictions of treatment outcome for the proposed subgroups. It provides a structured and simple-to-use option for classifying PJI in daily clinical practice and for scientific purposes.

Introduction: Historically, isolating patients diagnosed with musculoskeletal infections (MSIs) from the general orthopaedic population has been regarded a fundamental aspect of effective infection control. However, this remains controversial. Evolving perspectives on infection prevention, resource constraints, and staffing shortages necessitate a reassessment of current practices. This scoping review examines existing isolation policies for MSIs in orthopaedic practice and provides expert recommendations for hospital policymakers. Materials and methods: A systematic search of seven databases identified 23 320 articles. After deduplication and screening of 10 621 abstracts, 119 full texts were reviewed and 14 studies met the inclusion criteria. A total of 9 studies involved surgical wards, 5 examined general hospital wards, and 2 addressed orthopaedic patients. Results: Evidence indicates that individual isolation measures can reduce methicillin-resistant Staphylococcus aureus infections, whereas additional contact precautions or isolation showed no reduction of transmission risk for extended-spectrum beta-lactamase-producing Enterobacterales in endemic settings. For vancomycin-resistant Enterococcus (VRE), one study found a reduction in infections after implementing individual isolation, while another study reported no impact. No evidence supports separating patients with non-resistant MSIs from elective orthopaedic patients. Similarly, no data support the routine use of dedicated septic wards in orthopaedic practice. Conclusions: Effective infection control relies on hospital-wide strategies, provided that appropriate preventive measures and a high level of compliance with standard precautions are in place. Isolation practices should be selectively tailored to local epidemiology to balance infection prevention with optimal resource utilization. Managing MSIs in specialized centres, instead of dedicated septic wards, may deliver more effective care and adherence to standard precautions.

Chronic periprosthetic joint infections (PJIs) complicated by severe bone loss are challenging cases that require complex and specialized treatment approaches. Megaprosthetic replacement has gained in popularity in the setting of chronic hip and knee PJI; however, only a limited number of studies reporting on its utility are available. Thus, we aimed to review our cohort of patients with this specific condition who received modular megaprosthesis (MMP) as a limb salvage option in order to assess the failure rates, infection control, and implant longevity. We retrospectively reviewed electronic medical records of 61 patients who received MMPs for chronic hip and knee PJI between 2012 and 2024. The mean follow-up was $6.6\pm 3.5$  years. Failures were classified according to the Henderson classification. Kaplan-Meier survival curves were used to assess failure-free, infection-free, and overall implant survival. Cox regression analysis was performed to identify variables associated with MMP failure. Among the 61 patients, 37.7 % experienced any type of MMP failure, with infection recurrence being the most common reason for failure (60.9 %), followed by structural failure of the implant (17.4 %). At the 5-year follow-up, failure-free survival, infection-free survival, and revision-free survival were 65.8 %, 80.0 %, and 70.5 %, respectively. McPherson host grade C was significantly associated with implant failure (hazard ratio (HR) 3.1; 95 % confidence interval 1.4-7.6; $P=0.024$ ). Conclusively, MMPs represent a valuable treatment option for patients with chronic hip and knee PJI and large bone defects. While infection control is acceptable, the rates of any-type failure are high. These findings should be considered during preoperative patient counseling.