Validation of a treatment algorithm for orthopaedic implant-related infections with device-retention—results from a prospective observational cohort study

Clinical Application Study of External Fixation Treatment Using Removed Locking Plates in Patients with Failed Debridement and Antimicrobial Therapy for Infection after Internal Fixation of Fractures

Purpose: The main focus of this study is to investigate the clinical efficacy of external fixation treatment using removed locking plates in patients with failed debridement and antimicrobial therapy of infection after internal fixation of fractures. Patients and Methods: From January 2019 to January 2023, our medical institution treated 13 patients who had failed debridement and antimicrobial therapy for infection after internal fixation of fractures. All patients had their internal fixation devices removed, underwent thorough debridement, and then the removed locking plates were repurposed for external fixation treatment. Post-operatively, we observed the infection control status, fracture healing, and complications following locking plate external fixation. Results: Among all patients, there were seven males and six females, with an average age of 45.92 ± 13.19 years. The time interval from fracture internal fixation surgical procedure to the onset of infection was 7.08 ± 1.89 weeks, and the average debridement frequency was 1.62 ± 0.51 times. After treatment with external fixation using a removed locking plate, infection was controlled in 12 patients, ultimately achieving clinical bone healing. These 12 patients achieved clinical bone healing at a time of 7.50 ± 1.00 months, and the locking plate external fixation time was 9.83 ± 1.11 months. Conclusions: External fixation using removed locking plates appears to be an effective treatment option for patients who have failed debridement and antimicrobial therapy for infection after internal fixation of fractures. This approach effectively controls infection symptoms while not interfering with the fracture healing process. Additionally, this treatment option using a removed locked plate may potentially contribute to reducing patients' medical expenses.

Animal Models of Orthopedic Implant-Associated Infections and Revisions

Orthopedic implant-associated infections such as prosthetic joint infections (PJIs) lead to devastating complications for patients and impose significant financial burdens on the healthcare systems. Although the primary orthopedic implant associated infection rate is relatively low (0.3-9%), the reinfection rate after implant revisions can be as high as 20% to 40%. To evaluate novel therapeutic strategies for preventing and treating infections associated with primary and revision implants, it is essential to develop appropriate animal models that closely emulate clinical realities. Here we discuss existing animal models developed for orthopedic implant revision surgeries including small animal models in rats and mice, and larger animal models in rabbits, sheep, and mini-pigs. While larger animal models offer the advantage of more closely mimicking human surgical procedures, implant dimensions, and infection treatment protocols, rodent models are more cost-effective and better suited for screening experimental prophylaxes and therapeutics. Existing animal revision models have focused on primary infections established by Staphylococcal aureus (S. aureus) and revisions involving both one-stage and two-stage procedures. Further development of smaller animal implant revision models that implement more clinically relevant surgical procedures and recapitulate polymicrobial infections could facilitate the discovery and more rigorous evaluation of novel implant coating prophylaxes and therapeutics for reducing reinfection rates following implant revisions.

Methicillin-sensitive Staphylococcus aureus lineages contribute towards poor patient outcomes in orthopaedic device-related infections

Staphylococci are the most common cause of orthopaedic device-related infections (ODRIs), with Staphylococcus aureus responsible for a third or more of cases. This prospective clinical and laboratory study investigated the association of genomic and phenotypic variation with treatment outcomes in ODRI isolates. Eighty-six invasive S. aureus isolates were collected from patients with ODRI, and clinical outcome was assessed after a follow-up examination of 24 months. Each patient was then considered to have been 'cured' or 'not cured' based on predefined clinical criteria. Whole-genome sequencing and molecular characterization identified isolates belonging to globally circulating community- and hospital-acquired lineages. Most isolates were phenotypically susceptible to methicillin and lacked the staphylococcal cassette chromosome mec cassette [methicillin-susceptible S. aureus (MSSA); 94%] but contained several virulence genes, including toxins and biofilm genes. Whilst recognizing the role of the host immune response, we identified genetic variance, which could be associated with the infection severity or clinical outcome. Whilst this and several other studies reinforce the role antibiotic resistance [e.g. methicillin-resistant S. aureus (MRSA) infection] has on treatment failure, it is important not to overlook MSSA that can cause equally destructive infections and lead to poor patient outcomes.

Fracture-Related Infections

Fracture-related infections are challenging complications in orthopedic care, marked by infection at fracture or surgical sites, often involving biofilm-associated pathogens. They result in significant morbidity, prolonged hospitalizations, and high health care costs. Diagnosis integrates clinical, laboratory, and imaging findings, while treatment combines surgical debridement, implant management, and targeted antimicrobial therapy. Common pathogens include Staphylococcus aureus and Staphylococcus epidermidis, with culture-negative cases requiring advanced diagnostics. A multidisciplinary approach is critical to optimizing outcomes, addressing complications, and reducing the socioeconomic impact of these infections. Advances in treatment strategies continue to improve survival and quality of life for affected patients.

Fracture-Related Infections in the Foot and Ankle

Fracture-related infection (FRI) poses significant challenges in the management of foot and ankle fractures, potentially leading to functional impairment and heightened health care expenses. This review addresses the diagnosis, risk factors, and management strategies for FRI. Surgical management involves multidisciplinary collaboration, emphasizing debridement, antimicrobial therapy, and implant removal when indicated. Specific considerations for limited soft tissue coverage, tenuous blood supply, and fracture type in the foot and the ankle underscore the importance of tailored approaches to optimize outcomes and reduce complications in FRI management.

Timing in orthopaedic surgery - Rethinking traditional myths with a critical perspective

PURPOSE

Standard operating procedures aim to achieve a standardized and assumedly high-quality therapy. However, in orthopaedic surgery, the aspect of temporal urgency is often based on surgical tradition and experience. At a time of evidence-based medicine, it is necessary to question these temporal guidelines. The following review will therefore address the most important temporal guidelines in orthopaedic surgery and discuss their practical relevance and potential need for optimization.

METHODS

The systematic review features a literature review by database search in "PubMed" (https://pubmed.ncbi.nlm.nih.gov) for time to surgery in terms of (1) "proximal femoral fractures", (2) "femoral neck fractures", (3) "proximal humeral fractures", (4) "ligament and tendon injuries", (5) "spinal cord injuries", (6) "open fractures" and (7) "fracture-related infections". For every diagnosis, hypotheses on timing were set up and checked for evidence.

RESULTS

There is solid clinical evidence supporting the initiation of treatment within 24 h for specific conditions like the surgical treatment of proximal femur fractures and prompt decompression of spinal cord injuries. However, for other scenarios such as the 6-hour rule for open fractures, joint-preserving femoral neck fractures, timing of ligament injuries, humeral head fractures and fracture-related infections there is currently no reliable evidence to guide prompt surgical treatment.

CONCLUSION

Based on the current data, resource-adapted surgical planning seems reasonable. Further research in these areas is necessary to determine the best timing of treatment and address existing doubts.

Rifampin in device-related infections: Assessing the modern evidence

PURPOSE

Rifampin is commonly used to treat device-related infections (DRIs) due to its activity against biofilms, despite a history of limited clinical evidence to support its use. Evidence published since 2011 regarding rifampin use for DRIs is reviewed to describe the contemporary findings and ongoing considerations for rifampin use in these infections.

SUMMARY

A literature review was performed by searching PubMed and Google Scholar to identify relevant studies evaluating systemic rifampin use for the treatment of DRIs published from 2011 to 2023. References of identified studies were also screened for additional pertinent studies. Sixty-eight studies were identified, and 48 met the inclusion criteria. Rifampin efficacy was evaluated as both a primary outcome for cardiac device infections (n = 3) and prosthetic joint infections (n = 21) and as a nonprimary outcome (n = 24). Overall, the studies were primarily retrospective (n = 36) and small, with sample sizes ranging from 14 to 842 patients, and varied greatly with respect to prosthesis site, surgical intervention, pathogen, infection time frame, and antibiotic combination and duration. Efficacy outcome results varied greatly, with statistically significant evidence for the efficacy of rifampin combination in DRIs limited to a single study of prosthetic vascular graft infections and 13 studies of prosthetic joint infections.

CONCLUSION

The modern literature provides conflicting results regarding the benefit and lack of benefit with rifampin combination therapy in DRIs. Additional, robust research is imperative to solidify the ongoing role of rifampin in DRIs.

Developing a Risk Score for Predicting Multiple Revision Surgeries in Patients With Fracture-Related Infections

INTRODUCTION

Postoperative infections are a leading cause of morbidity following fracture repair. The purpose of this study is to develop a risk score predicting fracture-related infection (FRI) that will require one versus multiple revision surgeries related to infection eradication and bone healing.

METHODS

This is a retrospective cohort study conducted at a single level I trauma center from 2013 to 2020. Adults with FRIs were identified through review of an institutional database on musculoskeletal infections maintained jointly by the infectious disease division and the orthopaedic surgery department. Inclusion criteria were surgically managed fracture of the humerus, olecranon, radius/ulna, clavicle, pelvis, femur, tibia/fibula, and calcaneus with an FRI and adequate documentation present in the electronic medical record. Exclusion criteria included infected chronic osteomyelitis from a non-fracture-related pathology and follow-up less than 6 months. Risk factors leading to multiple surgeries in FRIs, including demographics, comorbidities, injury characteristics, perioperative data, and microbiology, were recorded. Logistic regression was done to select variables predictive of multiple revision surgeries. Four prespecified methods of covariate selection were used.

RESULTS

Eighty-eight patients underwent one FRI revision surgery, whereas 208 patients underwent two or more revision surgeries. From multivariable logistic regression, age older than 45 years (P < 0.001), purulent drainage at infection presentation (P < 0.001), and incomplete bone union at infection presentation (P = 0.013) were all markedly associated with multiple revision surgeries. The model of best fit was used to generate the risk score (area under ROC curve = 0.789). Variables included in the final risk score were age ≥ 45 years, purulent drainage, incomplete bony union, and wound dehiscence at infection presentation.

CONCLUSION

This study described a risk score for predicting multiple revision surgeries in patients with infection following fracture repair. Age older than 45 years, purulent drainage, and incomplete bony union at infection presentation were all markedly associated with multiple infection revision surgeries.

LEVEL OF EVIDENCE

III.

Fracture-Related Infection Diagnostic Tools in the Upper Extremity: A Scoping Review

Fracture-related infection (FRI) is a serious orthopaedic complication and its diagnosis, particularly in the upper extremity, is difficult and poorly defined in current literature. An international consensus definition of FRI was published in 2018, and our scoping review aims to investigate FRI diagnostic tools reported in the primary literature and their biostatistical utility. A review of articles generated from the PubMed/NCBI search term "fracture-related infection" was undertaken using PRISMA methodology. The included studies were published from January 2018 to June 2022 and referred to FRI diagnosis in the upper extremity. Of 224 returned studies, 32 articles were selected for further review after fellowship-trained senior author assessment. Of these, 16 had quantitative and reportable data regarding the diagnosis of upper extremity FRI. The most common diagnostic methods reported were CRP (8 studies), WBC (7), and ESR (5), consistent with 1 of the six suggestive criteria from the consensus definition. Meta-analysis was performed. Primary literature regarding the diagnosis of upper extremity fracture-related infections is sparse and variable despite FRI's diagnostic and therapeutic complexity. Recent literature does not reflect the proposed criteria of the 2018 consensus definition; further primary research is needed to validate these criteria and their accuracy and utility Level of Evidence: 3b.

Diagnostic Value of Neutrophil-Lymphocyte Ratio in Predicting Post-Operative Infection after Orthopedic Surgery: A Systematic Review and Meta-Analysis

Objective: This study aims to evaluate the predictive value of neutrophil-lymphocyte ratio (NLR) in determining infection after orthopedic surgery. Methods: A comprehensive search was conducted in PubMed, EBASE, CNKI, and Wanfang databases to identify relevant studies. The quality of the included studies was assessed using QUADAS-2. Data extraction was performed to calculate sensitivity, specificity, and other indicators. Bivariate mixed-effects meta-analysis was conducted using Stata software. The sources of heterogeneity were evaluated, and a summary receiver operating characteristic curve was generated. Results: A total of 16 literatures comprising 18 studies involving 3737 patients were included in this analysis. NLR demonstrated moderate sensitivity (0.77) and specificity (0.69) in diagnosing orthopedic post-operative infection, with an area under the curve of 0.80 and diagnostic odds ratio of 7.76. Significant heterogeneity was observed among the studies, primarily due to variations in surgical type, infection type, blood test timing, and NLR cutoff value. Fagan nomogram indicated that NLR could increase the positive posterior probability to 72% and decrease the negative posterior probability to 25%. The pooled effect of the likelihood ratio dot plot for diagnosis fell in the lower right quadrant. Deek funnel plot suggested no publication bias in this study. Conclusion: NLR holds certain value in diagnosing infection after orthopedic surgery and can provide additional information to assess the risk of infection. However, its predictive performance is influenced by various factors, and it cannot be used as a sole criterion for confirming the diagnosis. Prospective studies should be conducted in the future to optimize the diagnostic threshold and explore its combination with other indicators.

The surgical management of fracture-related infection. Surgical strategy selection and the need for early surgical intervention

The aim of this narrative review is to describe the various surgical management strategies employed in fracture-related infection (FRI), to explore how they are selected and discuss the rationale for early surgical intervention. Surgical treatment options in patients with FRI include debridement, antibiotics and implant retention (DAIR), revision (exchange) or removal. In selecting a treatment strategy, a variety of factors need to be considered, including the condition of the bone, soft tissues, host and causative microorganism. Irrespective of the selected treatment strategy, prompt surgical intervention should be considered in order to confirm the diagnosis of an FRI, to identify the causative organism, remove necrotic or non-viable tissue that can serve as a nidus for ongoing infection, ensure a healthy soft tissue envelope and to prevent the vicious cycle of infection associated with skeletal and/or implant instability. Ultimately, the objective is to prevent the establishment of a persistent infection. Urgent surgery may be indicated in case of active, progressive disease with systemic deterioration, local progression of infection, deterioration of soft tissues, or progressive fracture instability. In case of static disease, the patient should be monitored closely and surgery can be performed on an elective basis, allowing adequate time for optimisation of the host through risk factor modification, optimisation of the soft tissues and careful planning of the surgery.

Appropriate Duration of Antimicrobial Treatment for Prosthetic Joint Infections: A Narrative Review

Prosthetic joint infections are considered difficult to treat they needing aggressive surgery and long antimicrobial treatments. However, the exact duration of these therapies has been established empirically. In the last years, several studies have explored the possibility of reducing the length of treatment in this setting, with conflicting results. In this narrative review, we critically appraise the published evidence, considering the different surgical approaches (implant retention [DAIR] and one-step and two-step exchange procedures) separately. In patients managed with DAIR, usually treated for at least 12 weeks, a large, randomized trial failed to show that 6 weeks were non-inferior. However, another randomized clinical trial supports the use of 8 weeks, as long as the surgical conditions are favorable and antibiotics with good antibiofilm activity can be administered. In patients managed with a two-step exchange procedure, usually treated during 6 weeks, a randomized clinical trial showed the efficacy of a 4-week course of antimicrobials. Also, the use of local antibiotics may allow the use of even shorter treatments. Finally, in the case of one-step exchange procedures, there is a trend towards reducing the length of therapy, and the largest randomized clinical trial supports the use of 6 weeks of therapy.

Navigating the Challenges of Total Ankle Replacement: Deformity Correction and Infection Considerations

In recent years, total ankle replacement (TAR) has gained widespread acceptance as a surgical treatment for end-stage ankle arthritis. This shift is due to notable improvements in implant design, surgical instrumentation, technique, and surgeon expertise, resulting in high levels of patient satisfaction comparable to ankle fusion. Additionally, indications for TAR have expanded to include advanced deformities that were previously considered unsuitable for the procedure, making ankle arthrodesis the only option. Despite these advancements, TAR still carries a higher complication rate compared to other ankle surgeries. The complex anatomy of the ankle, coupled with limited soft tissue, presents significant challenges in managing complications associated with TAR.

[Structured approach for infected prosthesis]

BACKGROUND

Endoprosthesis infections represent a major challenge for doctors and patients. Due to the increase in endoprosthesis implantation because of the increasing life expectancy, an increase in endoprosthesis infections is to be expected. In addition to infection prophylaxis, methods of infection control become highly relevant, especially in the group of geriatric and multimorbid patients. The aim is to reduce the high 1‑year mortality from prosthesis infections through a structured algorithm.

ALGORITHM FOR PROSTHESIS INFECTIONS

Prosthesis infections can basically be divided into early and late infections. According to the criteria of the International Consensus Meeting, a late infection is defined as the occurrence more than 30 days after implantation. With respect to the planned approach, the (p)TNM classification offers an orientation. In the early postoperative interval the clinical appearance is crucial as in this phase neither laboratory parameters nor an analysis of synovial fluid show a high sensitivity. It is fundamental that, apart from patients with sepsis, environment diagnostics should be initiated. If a late infection is suspected, in addition to radiological diagnostics (X-ray, skeletal scintigraphy and if necessary, computed tomography, CT), laboratory (C-reactive protein, CRP, leukocytes, blood sedimentation, and if necessary, interleukin‑6, procalcitonin) and microbiological diagnostics (arthrocentesis with synovial analysis and microbiology) are indicated; however, in addition to the arthrocentesis result, the clinical appearance is crucial in cases where an exclusion cannot be confirmed by laboratory parameters. If an infection is confirmed, the treatment depends on the spectrum of pathogens, the soft tissue situation and the comorbidities, including a multistage procedure with temporary explantation and, if necessary, implantation of an antibiotic-containing spacer is necessary. A prosthesis preservation using the debridement, antibiotics and implant retention (DAIR) regimen is only appropriate in an acute infection situation. Basically, radical surgical debridement should be carried out to reduce the pathogen load and treatment of a possible biofilm formation for both early and late infections. The subsequent antibiotic treatment (short or long interval) should be coordinated with the infectious disease specialists.

CONCLUSION

A structured approach for prosthesis infections oriented to an evidence-based algorithm provides a sufficient possibility of healing. An interdisciplinary approach involving cooperation between orthopedic and infectious disease specialists has proven to be beneficial. Surgical treatment with the aim of reducing the bacterial load by removing the biofilm with subsequent antibiotic treatment is of intrinsic importance.

Fracture-related infection: Analysis of healthcare utilisation and associated costs

AIMS

A consensus definition of fracture related infection (FRI) has been created with the aim of standardising diagnosis and eliminating heterogeneity that prevents accurate comparison between existing studies. FRI remains one of the most challenging complications in musculoskeletal trauma surgery and carries with it a significant cost burden. A review of UK finances has not been completed utilising consensus diagnostic criteria. The goal of this study was to investigate the hospital-associated healthcare cost related to the treatment of FRI within an NHS major trauma centre.

METHOD

Through retrospective case-control analysis, 1240 patients with close fractures were identified. Of those, 21 patients with FRI were compared to 63 uninfected patients. Patients were matched based on fracture location, type of procedure and proximity in age. The costs assessed included hospitalisation, imaging, outpatient consultation, pharmaceuticals and procedure charges. Cost data was retrieved from healthcare resource group (HRG) guidelines, NHS Business Service Authority's (NBSA) prescription rates and internal costing.

RESULTS

The FRI group were found to incur a 2.51 increase in total medial healthcare cost compared to the control group (£22,058 vs £8798 [p < 0.001]), which was primarily due to increased procedural costs (£13,020 vs £6291 [p < 0.001]) and length of hospital stay (£7552 vs £2124 [p < 0.001]).

CONCLUSION

Whilst diagnosis of FRI has a more rigorous definition following the new consensus, prevalence and cost outcomes are similar to previous studies. Given the deficiency in funding and ongoing challenges of resource allocation to the NHS, it is prudent to incorporate studies such as this into stratifying departmental budgets and quality improvement.

LEVEL OF EVIDENCE

III.

Staphylococcus aureus From an Acute Fracture-related Infection Displays Important Bacteriological and Histopathologic Differences From a Chronic Equivalent in a Murine Bone Infection Model

BACKGROUND

Staphylococcus aureus is the leading pathogen in fracture-related infection. Previous in vitro experiments, in vivo testing in wax moth larvae, and genomic analysis of clinical S. aureu s isolates from fracture-related infection identified low-virulence (Lo-SA5464) and high-virulence (Hi-SA5458) strains. These findings correlated with acute fracture-related infection induced by Hi-SA5458, whereas Lo-SA5464 caused a chronic fracture-related infection in its human host. However, it remains unclear whether and to what extent the causative pathogen is attributable to these disparities in fracture-related infections.

QUESTION/PURPOSE

Are there differences in the course of infection when comparing these two different clinical isolates in a murine fracture-related infection model, as measured by (1) clinical observations of weight loss, (2) quantitative bacteriology, (3) immune response, and (4) radiographic and histopathologic morphology?

METHODS

Twenty-five (including one replacement animal) female (no sex-specific influences expected), skeletally mature C57Bl/6N inbred mice between 20 and 28 weeks old underwent femoral osteotomy stabilized by titanium locking plates. Fracture-related infection was established by inoculation of high-virulence S. aureus EDCC 5458 (Hi-SA5458) or low-virulence S. aureus EDCC 5464 (Lo-SA5464) in the fracture gap. Each of these groups consisted of 12 randomly assigned animals. Mice were euthanized 4 and 14 days postsurgery, resulting in six animals per group and timepoint. The severity and progression of infection were assessed in terms of clinical observation of weight loss, quantitative bacteriology, quantitative serum cytokine levels, qualitative analysis of postmortem radiographs, and semiquantitative histopathologic evaluation.

RESULTS

For clinical observations of weight change, no differences were seen at Day 4 between Hi-SA5458- and Lo-SA5464-infected animals (mean -0.6 ± 0.1 grams versus -0.8 ± 0.2 grams, mean difference -0.2 grams [95% CI -0.8 to 0.5 grams]; p =0.43), while at 14 days, the Hi-SA5458 group lost more weight than the Lo-SA5464 group (mean -1.55 ± 0.2 grams versus -0.8 ± 0.3 grams; mean difference 0.7 grams [95% CI 0.2 to 1.3 grams]; p = 0.02). Quantitative bacteriological results 4 days postoperatively revealed a higher bacterial load in soft tissue samples in Hi-SA5458-infected animals than in the Lo-SA5464-infected cohort (median 6.8 x 10 7 colony-forming units [CFU]/g, range 2.2 x 10 7 to 2.1 x 10 9 CFU/g versus median 6.0 x 10 6 CFU/g, range 1.8 x 10 5 to 1.3 x 10 8 CFU/g; difference of medians 6.2 x 10 7 CFU/g; p = 0.03). At both timepoints, mice infected with the Hi-SA5458 strain also displayed higher proportions of bacterial dissemination into organs than Lo-SA5464-infected animals (67% [24 of 36 organs] versus 14% [five of 36 organs]; OR 12.0 [95% CI 3.7 to 36]; p < 0.001). This was accompanied by a pronounced proinflammatory response on Day 14, indicated by increased serum cytokine levels of interleukin-1β (mean 9.0 ± 2.2 pg/mL versus 5.3 ± 1.5 pg/mL; mean difference 3.6 pg/mL [95% CI 2.0 to 5.2 pg/mL]; p < 0.001), IL-6 (mean 458.6 ± 370.7 pg/mL versus 201.0 ±89.6 pg/mL; mean difference 257.6 pg/mL [95% CI 68.7 to 446.5 pg/mL]; p = 0.006), IL-10 (mean 15.9 ± 3.5 pg/mL versus 9.9 ± 1.0 pg/mL; mean difference 6.0 pg/mL [95% CI 3.2 to 8.7 pg/mL]; p < 0.001), and interferon-γ (mean 2.7 ± 1.9 pg/mL versus 0.8 ± 0.3 pg/mL; mean difference 1.8 pg/mL [95% CI 0.5 to 3.1 pg/mL]; p = 0.002) in Hi-SA5458-infected compared with Lo-SA5464-infected animals. The semiquantitative histopathologic assessment on Day 4 revealed higher grades of granulocyte infiltration in Hi-SA5458-infected animals (mean grade 2.5 ± 1.0) than in Lo-SA5464-infected animals (mean grade 1.8 ± 1.4; mean difference 0.7 [95% CI 0.001 to 1.4]; p = 0.0498). On Day 14, bone healing at the fracture site was present to a higher extent in Lo-SA5464-infected animals than in Hi-SA5458-infected animals (mean grade 0.2 ± 0.4 versus 1.8 ± 1.2; mean difference -1.6 [95% CI -2.8 to -0.5]; p = 0.008).

CONCLUSION

Similar to septic infection in a human host, infection with Hi-SA5458 in this murine model was characterized by a higher bacterial load, more-pronounced systemic dissemination, and stronger systemic and local inflammation. Thus, there is strong support for the idea that pathogenic virulence plays a crucial role in fracture-related infections. To confirm our observations, future studies should focus on characterizing S. aureus virulence at the genomic and transcriptomic levels in more clinical isolates and patients. Comparing knockout and wildtype strains in vitro and in vivo, including the S. aureus strains studied, could confirm our findings and identify the genomic features responsible for S. aureus virulence in fracture-related infections.

CLINICAL RELEVANCE

For translational use, virulence profiles of S. aureus may be useful in guiding treatment decisions in the future. Once specific virulence targets are identified, one approach to fracture-related infections with high-virulence strains might be the development of antivirulence agents, particularly to treat or prevent septic dissemination. For fracture-related infections with low virulence, prolonged antimicrobial therapy or exchange of an indwelling implant might be beneficial owing to slower growth and persistence capacity.

Local Administration of Antibiotics in Orthopedics and Traumatology

2022 marks the 50th anniversary of the development of the antibiotic loaded PMMA chain. The loading of bone cements with antibiotics was a major advance in the treatment of musculoskeletal infections and is still a proven standard today. The research and use of novel antibiotic carriers continues to be an important part of research in the context of musculoskeletal infections. The article provides an overview of the various local antibiotics available and their specifics. In addition, current adapted treatment concepts are discussed.

Treatment of Fracture-Related Infection after Pelvic Fracture

BACKGROUND

The management of pelvic fractures is a significant challenge. Surgical site infection can result in the need for revision surgery, cause functional impairment, and lead to a prolonged length of stay and increased treatment costs. Although reports on fracture-related infection (FRI) after pelvic fracture fixation are sparsely reported in the literature, it is a serious complication. This study analysed patients with FRIs after pelvic fracture regarding patient characteristics, treatment strategies, and an evaluation of risk factors for FRI.

METHODS

In this retrospective single-centre study, FRI was diagnosed based on clinical symptoms of infection and a positive culture of a bacterial infection. Depending on the severity and acuteness of the infection, osseous stabilization was restored either via implant retention (stable implant, no osteolysis), exchange (loose implant or bony defect), or external fixation (recurrence of infection after prior implant retaining revision). Healing of infection was defined as no sign of recurring infection upon clinical, radiological, and laboratory examination in the last follow-up visit.

RESULTS

The FRI rate in our patient population was 7.5% (24/316). In 8/24 patients, the FRI occurred within the first three weeks after initial surgery (early) and 16/24 presented with a late onset of symptoms of FRI. A strategy of debridement, antibiotics, and implant retention (DAIR) was successful in 9/24 patients with FRI after pelvic fracture. A total of 10 patients required an exchange of osteo-synthetic implants, whereof three were exchanged to an external fixator. In five patients, we removed the implant because the fracture had already consolidated at the time of revision for infection. A total of 17/24 patients had a poly-microbial infection after a pelvic fracture and 3/24 patients died from post-traumatic multi-organ failure within the first 6 months after trauma. There were no cases of persistent infection within the remaining 21 patients.

CONCLUSIONS

Although poly-microbial infection is common in FRI after pelvic fracture, the recurrence rate of infection is relatively low. A complex pelvic trauma with significant soft tissue injury is a risk factor for recurrent infection and multiple revisions. A strategy of DAIR can be successful in patients with a stable implant. In cases with recurrent infection or an unstable fracture site, the exchange of implants should be considered.

Early switch from intravenous to oral antibiotic treatment in bone and joint infections

OBJECTIVES

The timing of the switch from intravenous (i.v.) to oral antibiotic therapy for orthopaedic bone and joint infections (BJIs) is debated. In this narrative article, we discuss the evidence for and against an early switch in BJIs.

DATA SOURCES

We performed a PubMed and internet search investigating the association between the duration of i.v. treatment for BJI and remission of infection among adult orthopaedic patients.

CONTENT

Among eight randomized controlled trials and multiple retrospective studies, we failed to find any minimal duration of postsurgical i.v. therapy associated with clinical outcomes. We did not find scientific data to support the prolonged use of i.v. therapy or to inform a minimal duration of i.v.

THERAPY

Growing evidence supports the safety of an early switch to oral medications once the patient is clinically stable.

IMPLICATIONS

After surgery for BJI, a switch to oral antibiotics within a few days is reasonable in most cases. We recommend making the decision on the time point based on clinical criteria and in an interdisciplinary team at the bedside.

New insights in lower limb reconstruction strategies

High Energy Musculoskeletal Traumas (HEMTs) represent a relevant problem for healthcare systems, considering the high social costs, and both the high morbidity and mortality. The poor outcomes associated with HEMT are related to the high incidence of complications, including bone infection, fracture malunion and non-union. The treatment of each of these complications could be extremely difficult. Limb reconstruction often needs multiple procedures, rising some questions on the opportunity in perseverate to try to save the affected limb. In fact, theoretically, amputation may guarantee better function and lower complications. However, amputation is not free of complication, and a high long-term social cost has been reported. A comprehensive literature review was performed to suggest possible ways to optimize the limb preservation surgeries of HEMT's complications in order to ameliorate their management.

Enough is enough: salvage procedures in severe periprosthetic joint infection

BACKGROUND

In severe cases of periprosthetic joint infection involving negative host-dependent factors, individual-based decisions between a curative therapy vs. salvage procedure are necessary. We aimed to review salvage procedures in severe periprosthetic joint infection cases, where a gold standard of a curative two-stage exchange can no longer be achieved. The options of knee arthrodesis, amputation, persistent fistula (stable drainage), or a debridement, antibiotics, and implant retention procedure in late-onset cases are discussed, including lifelong antibiotic suppression alone.

METHODS

We focused on known salvage procedures for severe periprosthetic joint infection of the hip and knee, such as amputation, arthrodesis, antibiotic suppression, persistent fistula, and debridement, antibiotics, and implant retention in late-stage infections, and the role of local antibiotics. The current literature regarding indications and outcomes was reviewed.

RESULTS

Whereas a successful single-stage above-knee amputation can be a curative effort in younger patients, this is associated with limited outcome in older patients, as the proportion who receive an exoprosthesis leading to independent mobility is low. Therefore, arthrodesis using an intramedullary modular nail is an option for limb salvage, pain reduction, and preservation of quality of life and everyday life mobility, when revision total knee arthroplasty is not an option. Carrying out a persistent fistula using a stable drainage system, as well as a lifelong antibiotic suppression therapy, can be an option, in cases where no other surgery is possible. Active clinical surveillance should then be carried out. A debridement, antibiotics, and implant retention procedure in combination with local degradable antibiotics can be used and is an encouraging new option, but should not been carried out twice.

CONCLUSION

Whereas the gold standard in periprosthetic joint infection treatment of late infections remains the exchange of the prosthesis, salvage procedures should be considered in the cases of reduced life expectancy, several recurrences of the infection, patients having preference and negative host factors. In these cases, the appropriate salvage procedure can temporarily lead to remission of the infection and the possibility to maintain mobility.

Efficacy and safety of different antimicrobial DURATions for the treatment of Infections associated with Osteosynthesis Material implanted after long bone fractures (DURATIOM): Protocol for a randomized, pragmatic trial

BACKGROUND

Infection associated with osteosynthesis material (IOM) is one of the most feared and challenging complications of trauma surgery and can cause significant functional loss, requiring multiple interventions and excessive consumption of antimicrobials. Evidence is needed about the best surgical procedure and the duration of antibiotic treatment according to the age of the implant or onset of infection symptoms, as it considers the biofilm formation and the state of fracture healing. There were not clinical trials evaluating the optimal duration of antibiotic therapy in IOM when implant is retained. Because there are antibiotics that have proven to be effective for the treatment of infection associated to implant, mainly in PJI, these antibiotics could be used in these infections. Investigating whether shorter duration of treatment is a priority in infectious diseases, as a way to reduce the exposure to antibiotics and help in controlling antimicrobial resistance and avoiding unnecessary adverse events and cost. We aim to describe the hypothesis, objectives, design, variables and procedures for a pragmatic randomized controlled trial comparing different durations of antibiotic treatment in IOM after long bone fractures treated with debridement and implant retention.

METHODS AND DESIGN

This is a multicenter, open-label, non-inferiority, randomized, controlled, pragmatic phase 3 trial, comparing different durations of antibiotic treatment in IOM after long bone fractures treated with debridement and implant retention. Patients with microbiologically confirmed IOM will be included. Eligible patients are those older than 14 years, with early IOM (up to 2 weeks after the implant surgery) and delayed IOM (between 3 and 10 weeks after the implant surgery) with stabilized fracture and absence of bone exposure who sign the informed consent. Randomization will be 1:1 to receive a short-term antibiotic treatment (8 weeks in early IOM and 12 weeks in delayed IOM) or a long-term antibiotic treatment (12 weeks in early IOM or until fracture healing or implant removal in delayed IOM). The antibiotic treatment will be that used in routine practice by the specialist in infectious diseases. The primary outcome is the composited variable "cure" that includes clinical cure, radiological healing, and definitive soft tissue coverage, which will be evaluated in the test of cure at 12 months after the end of antibiotic therapy. Adverse events, resistance development during therapy and functional status will be collected. A total of 364 patients are needed to show a 10% non-inferiority margin, with 80% power and 5% one-sided significance level.

DISCUSSION

If the hypothesis of non-inferiority of short vs. long antibiotic treatments is demonstrated, and the efficacy of antibiotics with less ecological impact in long treatments, the impact on reduction of bacterial resistance, toxicity and health costs will be observed.

TRIAL REGISTRATION

This trial is registered at ClinicalTrials.gov (NCT05294796) on Jan 26th 2022 and at the European Union Drug Regulating Authorities Clinical Trials (EUDRACT) (2021-003914-38) on Jul 16th 2021. The Sponsor Study Code is DURATIOM.

The Role of Coagulase-Negative Staphylococci Biofilms on Late-Onset Sepsis: Current Challenges and Emerging Diagnostics and Therapies

Infections are one of the most significant complications of neonates, especially those born preterm, with sepsis as one of the principal causes of mortality. Coagulase-negative staphylococci (CoNS), a group of staphylococcal species that naturally inhabit healthy human skin and mucosa, are the most common cause of late-onset sepsis, especially in preterms. One of the risk factors for the development of CoNS infections is the presence of implanted biomedical devices, which are frequently used for medications and/or nutrient delivery, as they serve as a scaffold for biofilm formation. The major concerns related to CoNS infections have to do with the increasing resistance to multiple antibiotics observed among this bacterial group and biofilm cells’ increased tolerance to antibiotics. As such, the treatment of CoNS biofilm-associated infections with antibiotics is increasingly challenging and considering that antibiotics remain the primary form of treatment, this issue will likely persist in upcoming years. For that reason, the development of innovative and efficient therapeutic measures is of utmost importance. This narrative review assesses the current challenges and emerging diagnostic tools and therapies for the treatment of CoNS biofilm-associated infections, with a special focus on late-onset sepsis.

Posttraumatic Osteomyelitis Risks Associated with NLRP3 Gene Polymorphisms in the Chinese Population

The purpose of this case-control study was to examine possible links between NLRP3 gene polymorphisms and the risk of developing posttraumatic osteomyelitis (PTOM) in the Chinese population. A total of 306 patients with PTOM and 368 normal controls were genotyped for NLRP3 (rs35829419, rs10754558, rs7525979, rs4612666), ELP2 (rs1785929, rs1789547, rs1785928, rs12185396, rs681757, rs8299, rs2032206, rs559289), STAT3 (rs4796793, rs744166, rs1026916, rs2293152, rs1053004), CASP1 (rs501192, rs580253, rs556205, rs530537), NFKBIA (rs696), NFKB1 (rs4648068), CARD8 (rs204321), and CD14 (rs2569190) using the genotyping technique SNaPshot. The genotype distributions of NLRP3 gene rs10754558 (p = 0.047) and rs7525979 (p = 0.048) significantly differed between the patients and the healthy controls. Additionally, heterozygous models indicated a significant association between NLRP3 rs10754558 and the likelihood of developing PTOM (OR = 1.600, p = 0.039), as did recessive and homozygous models of NLRP3 rs7525979 (OR = 0.248, p = 0.019 and 0.239, p = 0.016, respectively). Collectively, our findings suggest that, in the Chinese population, the risk of developing PTOM was increased by the association between NLRP3 rs10754558 and rs7525979. Therefore, our findings may provide novel insights and guidance in the prevention and development of PTOM.

Current Concepts of Fracture-Related Infection

Currently, fracture-related infection (FRI) still represents great challenges in front of orthopaedic surgeons, despite great advances that have been achieved regarding its diagnosis and treatment. Although both FRI and prosthetic joint infection (PJI) belong to osteoarticular infections and share similarities, FRI displays unique characteristics. Diagnosis of FRI is sometimes difficult owing to the nonspecific symptoms, and treatment is usually tricky, with a high risk of infection recurrence. In addition, the long disease course is associated with a significantly elevated risk of disability, both physically and psychologically. Moreover, such a disorder still poses heavy economic burdens to the patients, both personally and socially. Therefore, early diagnosis and reasonable treatment are the key issues for increasing the cure rate, decreasing the risks of infection relapse and disability, and improving the life quality and prognosis of the patients. In this review, we summarized the present concepts regarding the definition, epidemiology, diagnosis, and treatment of FRI.

Osteosynthesis-associated infection of the lower limbs by multidrug-resistant and extensively drug-resistant Gram-negative bacteria: a multicentre cohort study

Purpose: The purpose of this study was the clinical and therapeutic assessment of lower-limb osteosynthesis-associated infection (OAI) by multidrug-resistant (MDR) and extensively drug-resistant (XDR) Gram-negative bacteria (GNB), which have been poorly studied to date. Methods: A prospective multicentre observational study was conducted on behalf of ESGIAI (the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) Study Group on Implant-Associated Infections). Factors associated with remission of the infection were evaluated by multivariate and Cox regression analysis for a 24-month follow-up period. Results: Patients ( n = 57 ) had a history of trauma (87.7 %), tumour resection (7 %) and other bone lesions (5.3 %). Pathogens included Escherichia coli ( n = 16 ), Pseudomonas aeruginosa ( n = 14 ; XDR 50 %), Klebsiella spp. ( n = 7 ), Enterobacter spp. ( n = 9 ), Acinetobacter spp. ( n = 5 ), Proteus mirabilis ( n = 3 ), Serratia marcescens ( n = 2 ) and Stenotrophomonas maltophilia ( n = 1 ). The prevalence of ESBL (extended-spectrum β -lactamase), fluoroquinolone and carbapenem resistance were 71.9 %, 59.6 % and 17.5 % respectively. Most patients ( n = 37 ; 64.9 %) were treated with a combination including carbapenems ( n = 32 ) and colistin ( n = 11 ) for a mean of 63.3 d. Implant retention with debridement occurred in early OAI (66.7 %), whereas the infected device was removed in late OAI (70.4 %) ( p = 0.008 ). OAI remission was achieved in 29 cases (50.9 %). The type of surgery, antimicrobial resistance and duration of treatment did not significantly influence the outcome. Independent predictors of the failure to eradicate OAI were age > 60  years (hazard ratio, HR, of 3.875; 95 % confidence interval, CI95 %, of 1.540-9.752; p = 0.004 ) and multiple surgeries for OAI (HR of 2.822; CI95 % of 1.144-6.963; p = 0.024 ). Conclusions: Only half of the MDR/XDR GNB OAI cases treated by antimicrobials and surgery had a successful outcome. Advanced age and multiple surgeries hampered the eradication of OAI. Optimal therapeutic options remain a challenge.

Common bacteria and treatment options for the acute and chronic infection of the total ankle arthroplasty

BACKGROUND

There is little valid data available on managing infected total ankle arthroplasty (TAA).

METHODS

A single-center, retrospective evaluation from 20 patients with PJI (periprosthetic joint infection) of the ankle compared the bacteria isolated by preoperative arthrocentesis and intraoperative cultures to the pathogens of knee PJI. Long-term failure rates of irrigation and debridement (I&D) and polyethylene exchange, revision arthroplasty, and arthrodesis were analyzed.

RESULTS

The most common bacteria were Staphylococcus aureus and Coagulase-negative staphylococci. There was no significant difference when comparing the causing pathogens of PJI of the ankle with the knee. After a follow-up of 50,4 months, the long-term failure rate after I&D and polyethylene exchange was 40%, and of revision was 9%.

CONCLUSIONS

We concluded that the pathogenesis of PJI of the ankle and knee seems to be comparable. Regarding treatment options, we found that standardized techniques for PJIs of the knee have their limitations regarding infected TAA.

The Role of Nanoscale Distribution of Fibronectin in the Adhesion of Staphylococcus aureus Studied by Protein Patterning and DNA-PAINT

Staphylococcus aureus is a widespread and highly virulent pathogen that can cause superficial and invasive infections. Interactions between S. aureus surface receptors and the extracellular matrix protein fibronectin mediate the bacterial invasion of host cells and is implicated in the colonization of medical implant surfaces. In this study, we investigate the role of distribution of both fibronectin and cellular receptors on the adhesion of S. aureus to interfaces as a model for primary adhesion at tissue interfaces or biomaterials. We present fibronectin in patches of systematically varied size (100-1000 nm) in a background of protein and bacteria rejecting chemistry based on PLL-g-PEG and studied S. aureus adhesion under flow. We developed a single molecule imaging assay for localizing fibronectin binding receptors on the surface of S. aureus via the super-resolution DNA points accumulation for imaging in nanoscale topography (DNA-PAINT) technique. Our results indicate that S. aureus adhesion to fibronectin biointerfaces is regulated by the size of available ligand patterns, with an adhesion threshold of 300 nm and larger. DNA-PAINT was used to visualize fibronectin binding receptor organization in situ at ∼7 nm localization precision and with a surface density of 38-46 μm^-2, revealing that the engagement of two or more receptors is required for strong S. aureus adhesion to fibronectin biointerfaces.

Potential of Continuous Local Antibiotic Perfusion Therapy for Fracture-Related Infections

Introduction

Fracture-related infections (FRIs) are challenging for orthopedic surgeons, as conventional surgical treatment and systemic antimicrobial therapy cannot completely control local infections. Continuous local antibiotic perfusion (CLAP) is a novel and innovative therapy for bone and soft-tissue infections, and is expected to eradicate biofilms by maintaining a sustained high concentration of antimicrobial agents at the infected site. If CLAP therapy can eradicate infection even in cases with implants while preserving the implants, it would be an ideal and effective treatment for local refractory infections. This study aimed to evaluate the usefulness of novel CLAP therapy for FRIs.

Methods

Nine patients treated with CLAP therapy were retrospectively analyzed. The mean age was 65.9 (43–82) years, and the mean follow-up period was 14.9 (6–45) months. In all cases, the infected sites were related to the lower extremities (tibia, n = 6; fibula, n = 1; hip joint, n = 1; foot, n = 1). All patients underwent similar procedures for this therapy combined with negative-pressure wound therapy after thorough irrigation and debridement of infected tissues.

Results

The pathogens identified were Staphylococcus aureus (methicillin-resistant S. aureus, n = 5; methicillin-susceptible S. aureus, n = 1), Pseudomonas aeruginosa (n = 3), Enterococcus faecalis (n = 2), Corynebacterium (n = 1), and Enterobacter (n = 1); pathogens were not detected in one case. The mean duration of CLAP was 17.0 (7–35) days. In all cases, implants were preserved until bone union was achieved. Five cases relapsed; however, infection was finally suppressed in all cases by repeating this method. No side effects were observed.

Conclusion

This novel case series presents treatment outcomes using CLAP therapy for FRIs. This method has the potential to control the infection without removing the implants, because of the sustained high concentration of antimicrobial agents at the infected site, and could be a valuable treatment option for refractory FRIs with implants, in which bone union has not been achieved.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40121-022-00653-5.

Antimicrobial Photodynamic Therapy Involving a Novel Photosensitizer Combined With an Antibiotic in the Treatment of Rabbit Tibial Osteomyelitis Caused by Drug-Resistant Bacteria

Osteomyelitis is deep tissue inflammation caused by bacterial infection. If such an infection persists, it can lead to dissolution and necrosis of the bone tissue. As a result of the extensive use of antibiotics, drug-resistant bacteria are an increasingly common cause of osteomyelitis, limiting the treatment options available to surgeons. Photodynamic antibacterial chemotherapy has attracted increasing attention as a potential alternative treatment. Its advantages are a broad antibacterial spectrum, lack of drug resistance, and lack of toxic side effects. In this study, we explored the impact of the new photosensitizer LD4 in photodynamic antimicrobial chemotherapy (PACT), both alone and in combination with an antibiotic, on osteomyelitis. A rabbit tibial osteomyelitis model was employed and microbiological, histological, and radiological studies were performed. New Zealand white rabbits (n = 36) were randomly divided into a control group, antibiotic group, PACT group and PACT + antibiotic group for treatment. In microbiological analysis, a reduction in bacterial numbers of more than 99.9% was recorded in the PACT group and the PACT + antibiotic group 5 weeks after treatment (p < 0.01). In histological analysis, repair of the damaged bone tissue was observed in the PACT group, and bone repair in the PACT + antibiotic group was even more significant. In radiological analysis, the X-ray Norden score showed that the severity of bone tissue defects or destruction followed the pattern: PACT + antibiotic group < PACT group < antibiotic group < control group.

In Situ Coatings of Silver Nanoparticles for Biofilm Treatment in Implant-Retention Surgeries: Antimicrobial Activities in Monoculture and Coculture

Bacterial biofilms are indicated in most medical device-associated infections. Treating these biofilms is challenging yet critically important for applications such as in device-retention surgeries, which can have reinfection rates of up to 80%. This in vitro study centered around our new method of treating biofilm and preventing reinfection. Ionic silver (Ag, in the form of silver nitrate) combined with dopamine and a biofilm-lysing enzyme (α-amylase) were applied to model 4-day-old Staphylococcus aureus biofilms on titanium substrates to degrade the extracellular matrix of the biofilm and kill the biofilm bacteria. In this process, the oxidative self-polymerization of dopamine converted Ag ions into Ag nanoparticles that, together with the resultant self-adhering polydopamine (PDA), formed coatings that strongly bound to the treated substrates. Surprisingly, although these Ag/PDA coatings significantly reduced S. aureus growth in standard bacterial monoculture, they showed much lower antimicrobial activity in coculture of the bacteria and osteoblastic MC3T3-E1 cells in which the bacteria were also found attached to the osteoblasts. This S. aureus- osteoblast interaction was also linked to bacterial survival against gentamicin treatment observed in coculture. Our study thus provided clear evidence suggesting that bacteria's interactions with tissue cells surrounding implants may significantly contribute to their resistance to antimicrobial treatment.

Sonication in the diagnosis of fracture-related infections (FRI)-a retrospective study on 230 retrieved implants

BACKGROUND

In fracture-related infections (FRI), both the diagnosis of the infection and the identification of the causative pathogen are crucial to optimize treatment outcomes. Sonication has been successfully used for periprosthetic joint infections (PJI); however, its role in FRI remains unknown. Our aim was to determine the diagnostic accuracy (sensitivity, specificity) of sonicate fluid culture (SFC). The primary objective was to compare SFC with peri-implant tissue culture (PTC) overall and among subgroups using the consensus definition by Metsemakers et al. The secondary objective was to determine the yield of SFC in possible fracture-related infections (PFRI).

METHODS

From March 2017 to May 2019, 230 cases of retrieved implants were retrospectively reviewed. To perform sonication, explants were placed in sterile polypropylene jars intraoperatively. After treatment in an ultrasonic bath (Bandelin, Berlin, Germany), sonicate fluid was incubated into blood culture bottles, and conventional culturing was eventually performed. Sensitivity and specificity were determined using two-by-two contingency tables. McNemar's test was used to compare proportions among paired samples while Fisher's exact test was used for comparison between categorical variables.

RESULTS

Of the 230 cases, 107 were identified as FRI, whereas 123 were aseptic revision cases (ARC). Of the latter, 105 were labeled as PFRI. Sensitivity of SFC was higher in comparison with PTC, although this did not reach statistical significance (90.7% vs. 84.1%; p = .065). The specificity of SFC was significantly lower than that of PTC (73.2% vs. 88.6%; p = .003). In PFRI, SFC yielded significantly more positive results than PTC (33/105 vs. 14/105; p = .003). Overall, 142 pathogens were identified by SFC, whereas 131 pathogens were found by PTC.

CONCLUSIONS

We found that sonication of fracture fixation devices may be a useful adjunct in FRI, especially in "low-grade" infections lacking confirmatory clinical criteria. Standardized diagnostic protocols are warranted in order to further optimize the diagnostic accuracy.

The influence of duration of infection on outcome of debridement and implant retention in fracture-related infection

AIMS

The principle strategies of fracture-related infection (FRI) treatment are debridement, antimicrobial therapy, and implant retention (DAIR) or debridement, antimicrobial therapy, and implant removal/exchange. Increasing the period between fracture fixation and FRI revision surgery is believed to be associated with higher failure rates after DAIR. However, a clear time-related cut-off has never been scientifically defined. This systematic review analyzed the influence of the interval between fracture fixation and FRI revision surgery on success rates after DAIR.

METHODS

A systematic literature search was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, in PubMed (including MEDLINE), Embase, and Web of Science Core Collection, investigating the outcome after DAIR procedures of long bone FRIs in clinical studies published until January 2020.

RESULTS

Six studies, comprising 276 patients, met the inclusion criteria. Data from this review showed that with a short duration of infection (up to three weeks) and under strict preconditions, retention of the implant is associated with high success rates of 86% to 100%. In delayed infections with a fracture fixation-FRI revision surgery interval of three to ten weeks, absence of recurrent infection was reported in 82% to 89%. Data on late FRIs, with a fracture fixation-FRI revision surgery interval of more than ten weeks, are scarce and a success rate of 67% was reported.

CONCLUSION

Acute/early FRI, with a short duration of infection, can successfully be treated with DAIR up to ten weeks after osteosynthesis. The limited available data suggest that chronic/late onset FRI treated with DAIR may be associated with a higher rate of recurrence. Successful outcome is dependent on managing all aspects of the infection. Thus, time from fracture fixation is not the only factor that should be considered in treatment planning of FRI. Due to the heterogeneity of the available data, these conclusions have to be interpreted with caution. Cite this article: Bone Joint J 2021;103-B(2):213-221.

Controversy about the Role of Rifampin in Biofilm Infections: Is It Justified?

Rifampin is a potent antibiotic against staphylococcal implant-associated infections. In the absence of implants, current data suggest against the use of rifampin combinations. In the past decades, abundant preclinical and clinical evidence has accumulated supporting its role in biofilm-related infections.In the present article, experimental data from animal models of foreign-body infections and clinical trials are reviewed. The risk for emergence of rifampin resistance and multiple drug interactions are emphasized. A recent randomized controlled trial (RCT) showing no beneficial effect of rifampin in patients with acute staphylococcal periprosthetic joint infection treated with prosthesis retention is critically reviewed and data interpreted. Given the existing strong evidence demonstrating the benefit of rifampin, the conduction of an adequately powered RCT with appropriate definitions and interventions would probably not comply with ethical standards.

Virulence Factors in Coagulase-Negative Staphylococci

Coagulase-negative staphylococci (CoNS) have emerged as major pathogens in healthcare-associated facilities, being S. epidermidis, S. haemolyticus and, more recently, S. lugdunensis, the most clinically relevant species. Despite being less virulent than the well-studied pathogen S. aureus, the number of CoNS strains sequenced is constantly increasing and, with that, the number of virulence factors identified in those strains. In this regard, biofilm formation is considered the most important. Besides virulence factors, the presence of several antibiotic-resistance genes identified in CoNS is worrisome and makes treatment very challenging. In this review, we analyzed the different aspects involved in CoNS virulence and their impact on health and food.

Methods and probability of success after early revision of prosthetic joint infections with debridement, antibiotics and implant retention

Prosthetic joint infection (PJI) is a rare-and dreaded-complication of arthroplasty requiring multidisciplinary care. Given the dual goal of treating the infection and maintaining satisfactory function, it is preferable to determine how and when the implanted components can be retained. Bacteria and fungi organize themselves into biofilms that shield them from antibiotics and the immune system. This biofilm is in place after 15 days of active infection. Some antibiotics have a better activity on biofilms. The following factors have a negative impact on the probability of a successful debridement, antibiotics and implant retention (DAIR) intervention: fracture or revision, use of cement, bacteremia, kidney and/or liver failure, immunosuppression and elevated CRP. Hematogenous infections have a worse prognosis than early postoperative infections. Using a decision algorithm increases the chances of DAIR being successful. The KLIC score applies to early postoperative infections (<4 weeks postoperative and<3 weeks from the first signs) while the CRIME-80 score applies to hematogenous infections (<3 weeks from the first signs). Arthroscopic treatments have no role here, whereas DAIR through an arthrotomy is well standardized. Wide spectrum antibiotic therapy, secondarily adapted to the causative microorganism, is indicated for a total of 3 months. The results against the infection are mixed, although following a decision algorithm resolves the infection in about 75% of cases. The functional outcomes and quality of life are close to those of patients who have undergone primary joint replacement. It is not recommended to carry out a second DAIR if the first one fails. It is logical to apply the principles set out for the hip and knee to other joint replacements, and to use the same algorithm. For the upper limb, and especially for reverse shoulder arthroplasty, one must be careful about Cutibacterium acnes infections as they are hard to diagnose. Surgeons should not hesitate to contact a referral center for any PJI, although it is preferable that early infections be treated at the facility that performed the implantation.

Antibiofilm efficacy of focused high-energy extracorporeal shockwaves and antibiotics in vitro

Aims

Biofilm formation is one of the primary reasons for the difficulty in treating implant-related infections (IRIs). Focused high-energy extracorporeal shockwave therapy (fhESWT), which is a treatment modality for fracture nonunions, has been shown to have a direct antibacterial effect on planktonic bacteria. The goal of the present study was to investigate the effect of fhESWT on Staphylococcus aureus biofilms in vitro in the presence and absence of antibiotic agents.

Methods

S. aureus biofilms were grown on titanium discs (13 mm × 4 mm) in a bioreactor for 48 hours. Shockwaves were applied with either 250, 500, or 1,000 impulses onto the discs surrounded by either phosphate-buffered saline or antibiotic (rifampin alone or in combination with nafcillin). The number of viable bacteria was determined by quantitative culture after sonication. Representative samples were taken for scanning electron microscopy.

Results

The application of fhESWT led to a ten-fold reduction in bacterial counts on the metal discs for all impulse numbers compared to the control (p < 0.001). Increasing the number of impulses did not further reduce bacterial counts in the absence of antibiotics (all p > 0.289). Antibiotics alone reduced the number of bacteria on the discs; however, the combined application of the fhESWT and antibiotic administration further reduced the bacterial count compared to the antibiotic treatment only (p = 0.032).

Conclusion

The use of fhESWT significantly reduced the colony-forming unit (CFU) count of a S. aureus biofilm in our model independently, and in combination with antibiotics. Therefore, the supplementary application of fhESWT could be a helpful tool in the treatment of IFIs in certain cases, including infected nonunions.

Cite this article: Bone Joint Res 2021;10(1):77–84.

Morbid Obesity Is a Risk Factor for Infection Recurrence Following Debridement, Antibiotics, and Implant Retention for Periprosthetic Joint Infection

BACKGROUND

Although morbid obesity is an established risk factor for periprosthetic joint infection following total hip arthroplasty and total knee arthroplasty, little is known regarding the infection control rate of this cohort following debridement, antibiotics, and implant retention (DAIR). The purpose of this study is to investigate the infection control rate following DAIR in a morbidly obese patient cohort compared to a nonobese patient cohort and discern the relationship between time from diagnosis to treatment and risk of DAIR failure.

METHODS

Results of all DAIR procedures were retrospectively reviewed across 4 institutions. Those with a body mass index of at least 40 kg/m² were matched 2:1 on the basis of patient age, sex, date of surgery, and presence of staphylococcal species in culture to a cohort of patients with body mass index of <30 kg/m². Demographic variables were collected for each patient. Kaplan-Meier survivorship curves were constructed and multivariable Cox regression was performed for analysis.

RESULTS

The morbidly obese group experienced a higher treatment failure rate (57.9%) compared to the nonobese group (36.8%; P = .035). Morbid obesity and major depressive disorder/generalized anxiety disorder diagnosis significantly increased the risk of failure, with hazard ratios of 1.82 and 2.09, respectively. Morbidly obese patients who received DAIR within 48 hours of symptom presentation did not face an increased risk of reinfection compared to nonobese patients.

CONCLUSION

Our findings suggest morbidly obese patients face an increased risk of DAIR failure; however, this risk can be mitigated if DAIR is received within 48 hours of symptom onset.

Salvage procedure for chronic periprosthetic knee infection: the application of DAIR results in better remission rates and infection-free survivorship when used with topical degradable calcium-based antibiotics

PURPOSE

Debridement, systemic antibiotics and implant retention (DAIR) is very successful for early periprosthetic joint infection (PJI), but can fail in late-onset cases. We selected patients with PJI who were unsuitable for two-stage exchange total knee arthroplasty (TKA) and compared the outcomes of DAIR with or without degradable calcium-based antibiotics.

METHODS

All patients fulfilled the criteria for late-onset PJI of TKA, as defined by an International Consensus Meeting in 2013, but were unsuitable for multistage procedures and TKA exchange due to operative risk. Fifty-six patients (mean age: 70.6 years, SD ± 10.8), in two historical collectives, were treated using a single-stage algorithm consisting of DAIR without antibiotics (control group, n = 33, 2012-2014), or by DAIR following the implantation of degradable antibiotics as indicated by an antibiogram (intervention group, n = 23, 2014-2017). OSTEOSET^® (admixed vancomycin/tobramycin), and HERAFILL-gentamicin^® were used as carrier systems. The primary endpoint was re-infection or surgical intervention after DAIR.

RESULTS

There were no significant differences between the two groups in terms of mean age, Charlson comorbidity index or the rate of mixed infections. Overall, 65.2% of patients achieved remission in the intervention group compared with only 18.2% in the control group (p < 0.001); 50% of re-infections in the intervention group even occurred after 36 months. Kaplan-Meier analysis showed that, compared with controls, the intervention group experienced significantly longer 3-year infection-free survival.

CONCLUSION

DAIR shows poor efficacy in difficult-to-treat cases, as demonstrated in our control group, which had a re-infection rate of 81.8%. In contrast, a DAIR group receiving topical calcium-based antibiotics showed significantly higher 3-year infection-free survival. Therefore, the combination of DAIR and degradable antibiogram-based local antibiotics is a reasonable salvage procedure for this body of patients. This is important as the number of severely sick patients who are too old for appropriate PJI treatment is estimated to increase significantly due to demographic change.

Dual Surgical Setup May Improve Infection Control Rate of Debridement and Implant Retention Procedures for Periprosthetic Infections of the Hip and Knee

BACKGROUND

Debridement, antibiotics, and implant retention (DAIR) is an appealing treatment option for periprosthetic joint infection (PJI) due to its low cost and low morbidity. There are many nonmodifiable risk factors for DAIR failure that have previously been established. A dual DAIR setup constitutes establishing a new, sterile field after the initial debridement. The purpose of this study is to determine whether the modifiable surgical technique of a dual setup improves the infection control rate following PJI.

METHODS

A retrospective study was conducted from January 1, 2000 to December 31, 2017 to identify patients who underwent a DAIR procedure as initial surgical treatment for PJI of the hip or knee. Patients were divided between 2 groups, failed and successful DAIR procedures. Failure was defined as infection recurrence requiring surgical intervention. Demographic (age, gender, body mass index, smoking status, American Society of Anesthesiologists status), preoperative comorbidity (hypertension, cardiac disease, diabetes status, depression or anxiety diagnosis, pulmonary disease), operating surgeon, single vs dual setup, hospital, use of long-term antibiotics postoperatively (greater than 6 weeks of intravenous antibiotics), joint, and laterality data were compared between cohorts using multivariate regression analysis.

RESULTS

Two hundred sixty-three patients were identified who underwent DAIR as the exclusive and initial treatment for PJI. Single vs dual setup, knee vs hip joint, cardiac or vascular disease diagnosis, major depressive disorder or generalized anxiety disorder diagnosis, and staphylococcal infections were found to be independent predictive variables for DAIR failure.

CONCLUSION

In our series, the dual setup DAIR was a modifiable surgical technique that significantly decreased the risk of infection recurrence compared to single setup DAIR.

Treatment of contaminated radial fracture in Sprague-Dawley rats by application of a degradable polymer releasing gentamicin

Fracture-related infections remain a leading cause of morbidity and mortality. We aimed to establish a simple contaminated radial osteotomy model to assess the efficacy of a biodegradable polymer poly(sebacic-co-ricinoleic acid) [p(SA-RA)] containing 20% w/w gentamicin. A unilateral transverse osteotomy was induced in Sprague-Dawley (SD) rats, followed by application of Staphylococcus aureus suspension over the fracture. After successfully establishing the contaminated open fracture model, we treated the rats either systemically (intraperitoneal cefuroxime), locally with p(SA-RA) containing gentamicin, or both. Control groups included non-contaminated group and contaminated groups that were either untreated or treated with the polymer alone. After 4 weeks, the bones were subjected to micro-CT scanning and microbiological and histopathology evaluations. Micro-CT analysis revealed similar changes in the group subjected to both local and systemic treatment as in the non-contaminated control group. Lack of detectable bacterial growth was noted in most animals of the group subjected to both local and systemic treatment, and all samples were negative for S. aureus. Histopathological evaluation revealed that all treatment modalities containing antibiotics were highly effective in reducing infection and promoting callus repair, resulting in early bone healing. While p(SA-RA) containing gentamicin treatment showed better results than cefuroxime, the combination of local and systemic treatment displayed the highest therapeutic potential in this model.

[Advances in clinical diagnosis and treatment of chronic osteomyelitis in adults]

OBJECTIVE

To review the progress of clinical diagnosis and treatment of chronic osteomyelitis in adults.

METHODS

The literature related to chronic osteomyelitis in recent years was extensively reviewed, and the clinical diagnosis and treatment methods were summarized.

RESULTS

Clinical characteristics and laboratory examination can help to diagnose chronic osteomyelitis in adults. Pathogenic identification is the basis for choosing antibiotics. Diagnostic imaging is specific. The treatment includes systemic treatment and local treatment, and the local treatment is the key to radical cure.

CONCLUSION

The diagnosis of chronic osteomyelitis in adults should be made as early as possible. According to the anatomical and physiological classification of the patients, the appropriate treatment plan should be made.

Associations between Interleukin Gene Polymorphisms and Risks of Developing Extremity Posttraumatic Osteomyelitis in Chinese Han Population

This case-control study aimed to investigate potential associations between interleukin (IL) gene polymorphisms and the risks of developing extremity posttraumatic osteomyelitis (PTOM) in Chinese Han population. Altogether, 189 PTOM patients and 200 healthy controls were genotyped of IL-1α (rs17561, rs1800587), IL-1β (rs16944, rs1143627, rs1143634, rs2853550), IL-1RN (rs4251961, rs419598, rs315951), IL-4 (rs2243248, rs2243250), IL-6 (rs1800795, rs1800796, rs1800797), IL-8 (rs4073, rs2227306, rs2227307), IL-10 (rs3024491, rs3024496, rs1800871, rs1800872, rs1800896), IL-17A (rs2275913), and IL-17F (rs763780) using the SNaPshot genotyping method. Statistical differences were observed regarding the genotype distributions of rs16944 (P = 0.049) and rs4251961 (P = 0.007) between the patients and healthy controls. In addition, significant associations were found between rs16944 and the risk of PTOM development by dominant (OR = 1.854, P = 0.017), homozygous (OR = 1.831, P = 0.041), and heterozygous (OR = 1.869, P = 0.022) models, and of rs1143627 by dominant (OR = 1.735, P = 0.032) and homozygous (OR = 1.839, P = 0.040) models. Moreover, significant links were also identified between rs4251961 and the susceptibility to PTOM by dominant (OR = 0.446, P = 0.005) and heterozygous (OR = 0.409, P = 0.003) models, and of rs1800796 by dominant (OR = 4.184, P = 0.029), homozygous (OR = 4.378, P = 0.026), and heterozygous (OR = 3.834, P = 0.046) models. The present outcomes demonstrated that rs16944, rs1143627, and rs1800796 associate with increased risks, while rs4251961 links to a decreased risk of PTOM development in Chinese Han population.

Plasma d-Dimer Levels in Non-prosthetic Orthopaedic Implant Infection: Can it Aid Diagnosis?

PURPOSE

d-Dimer estimation has been proposed as a reliable biomarker in prosthetic joint infections. Its role in non-prosthetic orthopaedic implant infections has, however, not been studied. The objectives of this study were to assess the levels of plasma d-Dimer in non-prosthetic orthopaedic implant infection. The diagnostic efficiency of d-dimer on orthopaedic implant-related infection was evaluated.

METHODS

The study was designed as a cross-sectional comparative study. Patients who presented with orthopaedic implant-related infection as diagnosed by modified MSIS criteria were allocated to case group (n = 49) and patients who underwent surgical procedures with orthopaedic implants with no evidence of infection at 6 weeks postoperatively were allocated to the control group (n = 48). Serum d-Dimer levels were assessed quantitatively using immunoturbidimetric assays in both groups and compared between both groups.

RESULTS

The mean (± SD) value of serum d-Dimer in case group was 0.64 (± 0.45) μg/ml and control group was 0.77 (± 0.47) μg/ml. No significant difference was found in serum d-Dimer levels between cases and control groups (p value = 0.183). The diagnostic accuracy of d-dimer in orthopaedic implant-related infection also could not be demonstrated.

CONCLUSION

The findings of d-dimer as a marker for the diagnosis of prosthetic joint infections cannot be extrapolated to non-prosthetic orthopaedic implant infection.

Calculated parenteral initial treatment of bacterial infections: Bone and joint infections

This is the 10^th chapter of the guideline “Calculated initial parenteral treatment of bacterial infections in adults – update 2018” in the 2^nd updated version. The German guideline by the Paul-Ehrlich-Gesellschaft für Chemotherapie e.V. (PEG) has been translated to address an international audience.

This chapter deals with bacterial Infections of bones, joints and prosthetic joints. One of the most pressing points is that after an initial empirical therapy a targeted antimicrobial which penetrates well to the point of infection and is tolerated well over the usually long duration of the therapy is chosen.

Risk factors, diagnosis and management of prosthetic joint infection after total hip arthroplasty

Introduction: Although a relatively rare complication, the incidence and prevalence of prosthetic joint infection (PJI) is certainly rising. This is mainly due to the number of arthroplasties performed each year and our ability to capture more cases. There is currently no consensus in the optimal diagnosis and management of the infected total hip arthroplasty. Various management techniques have been described in literature.Areas covered: We discuss and summarize the literature in diagnosing prosthetic joint infection (PJI) including next-generation sequencing. An in-depth critical analysis of the biomarkers and the novel tests available in the market is reviewed including the evolving nature of the diagnostic criteria for PJI. The key issues in managing infected THA are identified.Expert commentary: The senior authors' expert opinion on diagnostic criteria is discussed. We also stress the importance of tissue/fluid analysis of microbiology and histology being key to diagnosis of PJI. The indications of one-stage versus two-stage revision arthroplasty is examined, including techniques for successful one-stage revision.

Pathogenesis and management of fracture-related infection

BACKGROUND

Both fracture-related infections (FRIs) and periprosthetic joint infections (PJIs) include orthopaedic implant-associated infections. However, key aspects of management differ due to the bone and soft tissue damage in FRIs and the option of removing the implant after fracture healing. In contrast to PJIs, research and guidelines for diagnosis and treatment in FRIs are scarce.

OBJECTIVES

This narrative review aims to update clinical microbiologists, infectious disease specialists and surgeons on the management of FRIs.

SOURCES

A computerized search of PubMed was performed to identify relevant studies. Search terms included 'Fracture' and 'Infection'. The reference lists of all retrieved articles were checked for additional relevant references. In addition, when scientific evidence was lacking, recommendations are based on expert opinion.

CONTENT

Pathogenesis, prevention, diagnosis and treatment of FRIs are presented. Whenever available, specific data of patients with FRI are discussed.

IMPLICATIONS

Management of patients with FRI should take into account FRI-specific features. Treatment pathways should implement a multidisciplinary approach to achieve a good outcome. Recently, international consensus guidelines were developed to improve the quality of care for patients suffering from this severe complication, which are highlighted in this review.