Fracture-related infection: current methods for prevention and treatment

Repetitive combined doses of bacteriophages and gentamicin protect against Staphylococcus aureus implant-related infections in Galleria mellonella

Aims

Bacteriophages infect, replicate inside bacteria, and are released from the host through lysis. Here, we evaluate the effects of repetitive doses of the Staphylococcus aureus phage 191219 and gentamicin against haematogenous and early-stage biofilm implant-related infections in Galleria mellonella.

Methods

For the haematogenous infection, G. mellonella larvae were implanted with a Kirschner wire (K-wire), infected with S. aureus, and subsequently phages and/or gentamicin were administered. For the early-stage biofilm implant infection, the K-wires were pre-incubated with S. aureus suspension before implantation. After 24 hours, the larvae received phages and/or gentamicin. In both models, the larvae also received daily doses of phages and/or gentamicin for up to five days. The effect was determined by survival analysis for five days and quantitative culture of bacteria after two days of repetitive doses.

Results

In the haematogenous infection, a single combined dose of phages and gentamicin, and repetitive injections with gentamicin or in combination with phages, resulted in significantly improved survival rates. In the early-stage biofilm infection, only repetitive combined administration of phages and gentamicin led to a significantly increased survival. Additionally, a significant reduction in number of bacteria was observed in the larvae after receiving repetitive doses of phages and/or gentamicin in both infection models.

Conclusion

Based on our results, a single dose of the combination of phages and gentamicin is sufficient to prevent a haematogenous S. aureus implant-related infection, whereas gentamicin needs to be administered daily for the same effect. To treat early-stage S. aureus implant-related infection, repetitive doses of the combination of phages and gentamicin are required.

Early Management for Fracture-Related Infection: A Literature Review

Fracture-related infections (FRIs), as shown in the literature, represent one of the main complications of trauma surgery. They are a consequence of an implant-related "biofilm" formation and are a challenge for surgeons, microbiologists, and infectious disease specialists. For a correct diagnosis, careful clinical evaluation, to look for signs/symptoms attributable to an infectious condition, and instrumental examinations, to highlight the site of infection, its extent, and its severity, are both essential. Unfortunately, due to the lack of data in the literature, there is no consensus about guidelines on the diagnosis and treatment of FRIs. The purpose of this study is to present an up-to-date concept evaluation of the diagnostic procedures and treatment options available in the management of fracture-related infections.

High Rate of Undetected Infections in Failed Osteosynthesis of Pertrochanteric Fractures

OBJECTIVE

The objective of this study was to assess the incidence of infection in patients with cutout after proximal femur fracture (PFF) osteosynthesis.

METHODS

DESIGN

Retrospective cohort study.

SETTING

Third-level trauma center.

PATIENT SELECTION CRITERIA

Patients presenting with a cutout following PFF (OTA/AO 31A) osteosynthesis, between January 2007 and December 2020.

OUTCOME MEASUREMENTS AND COMPARISONS

The primary outcome was infection according to the European Bone and Joint Infection Society criteria.

RESULTS

Sixty-seven patients presenting with a cutout were included, with mean age of 83.3 years (range 63-96), and 51 (76.1%) were women. Of all cases, 16 (24.7%) presented a concomitant infection. The presence of concomitant infection was suspected preoperatively in only 3 of the cases. A subgroup analysis was performed between the cases with infection and those without infection, the groups being comparable in terms of demographic data and postoperative radiological criteria. Patients with underlying infection had a higher rate of surgical wound complication (56.3% vs. 22%, P = 0.014) and higher rates of leukocytosis (11.560 vs. 7.890, P = 0.023).

CONCLUSION

Faced with a cutout after osteosynthesis of a PFF, underlying infection should be considered as a possible etiological factor.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Long-Term Outcomes Following Single-Stage Reamed Intramedullary Exchange Nailing in Apparently Aseptic Femoral Shaft Nonunion with Unsuspected Proof of Bacteria

Background: The aim of this study was to evaluate detection rates and risk factors for unsuspected proof of bacteria, as well as clinical and radiologic outcomes following femoral shaft nonunion without clinical signs of infection treated by a single-stage surgical revision procedure including reamed intramedullary exchange nailing. Methods: A retrospective cohort study was performed in a European level I trauma center between January 2015 and December 2022. Fifty-eight patients were included who underwent reamed intramedullary exchange nailing as a single-step procedure for surgical revision of posttraumatic diaphyseal femoral nonunion without any indications of infection in medical history and without clinical signs of local infection. Clinical details of the patients were analyzed and functional and radiologic long-term outcomes were determined. Results: In all patients, with and without proof of bacteria osseous, healing could be observed. The physical component summary of the SF-12 demonstrated significantly better results at least one year after the final surgical revision in case of a negative bacterial culture during exchange nailing. Conclusions: Clinical long-term outcomes demonstrated a trend towards better results following femoral shaft nonunion revision if there was no evidence for the presence of low-grade infected nonunion. In this case, a single-stage surgical procedure may be recommended.

Developing an antibiogram for empiric antibiotic prescribing for adult non-spinal orthopaedic infections in a developing world setting

PURPOSE

Empiric antibiotic strategies in the treatment of fracture-related infections, chronic osteomyelitis, prosthetic joint infection, and septic arthritis should be based on local microbiological antibiograms. This study aims to describe the microbiology and review the antibiogram profiles of bacterial isolates from patients undergoing surgical treatment for non-spinal orthopaedic infections, to identify the most appropriate empiric antibiotic strategy.

METHODS

A retrospective review was performed of all cases of non-spinal orthopaedic infections treated surgically from 1 January 2018 to 31 December 2018. The National Health Laboratory Service microbiology database was used to identify all intra-operative microbiological specimens obtained from orthopaedic patients, and data were correlated with the orthopaedic surgical database. Cases were divided into fracture-related infections, chronic osteomyelitis, prosthetic joint infection, and septic arthritis. Antibiotic susceptibility data were used to predict the efficacy of different empiric antibiotic regimens.

RESULTS

A total of 107 cases were included in the study; 184 organisms were cultured. Overall, the most common organism cultured was Staphylococcus aureus (25%) followed by Acinetobacter baumannii (9%), Enterococcus faecalis (7%) and Enterobacter cloacae (5%). Across all categories the oral antibiotic combination with the highest effectiveness (81%) would have been a combination of co-trimoxazole, ciprofloxacin and amoxicillin. The most effective intravenous antibiotic combination would have been either piperacillin-tazobactam, amikacin and vancomycin or meropenem and vancomycin; 90% of tested isolates were susceptible to either of these combinations.

CONCLUSION

Antibiogram profiles can serve to guide to empiric antibiotic choice in the management of different categories of non-spinal orthopaedic infections.

Surprise positive culture rate in the treatment of presumed aseptic long-bone nonunion: a systematic review with meta-analysis of 2397 patients

INTRODUCTION

In pre-operatively presumed aseptic nonunions, the definitive diagnosis of infection relies on intraoperative cultures. Our primary objective was to determine (1) the rate of surprise positive intraoperative cultures in presumed aseptic long-bone nonunion (surprise positive culture nonunion), and (2) the rate of surprise positive cultures that represent infection vs. contamination. Secondary objectives were to determine the healing and secondary surgery rates and to identify cultured micro-organisms.

MATERIALS AND METHODS

We performed a systematic literature search of PubMed, Embase and Cochrane Libraries from 1980 until December 2021. We included studies reporting on ≥ 10 adult patients with a presumed aseptic long-bone nonunion, treated with a single-stage surgical protocol, of which intraoperative cultures were reported. We performed a meta-analysis for: (1) the rates of surprise positive culture nonunion, surprise infected nonunion, and contaminated culture nonunion, and (2) healing and (3) secondary surgery rates for each culture result. Risk of bias was assessed using the QUADAS-2 tool.

RESULTS

21 studies with 2,397 patients with a presumed aseptic nonunion were included. The rate of surprise positive culture nonunion was 16% (95%CI: 10-22%), of surprise infected nonunion 10% (95%CI: 5-16%), and of contaminated culture nonunion 3% (95%CI: 1-5%). The secondary surgery rate for surprise positive culture nonunion was 22% (95%CI: 9-38%), for surprise infected nonunion 14% (95%CI 6-22%), for contaminated culture nonunion 4% (95%CI: 0-19%), and for negative culture nonunion 6% (95CI: 1-13%). The final healing rate was 98% to 100% for all culture results. Coagulase-negative staphylococci accounted for 59% of cultured micro-organisms.

CONCLUSION

These results suggest that surprise positive cultures play a role in the clinical course of a nonunion and that culturing is important in determining the etiology of nonunion, even if the pre-operative suspicion for infection is low. High healing rates can be achieved in presumed aseptic nonunions, regardless of the definitive intraoperative culture result.

Alginate microbeads and hydrogels delivering meropenem and bacteriophages to treat Pseudomonas aeruginosa fracture-related infections

Bacteriophage (phage) therapy has shown promise in treating fracture-related infection (FRI); however, questions remain regarding phage efficacy against biofilms, phage-antibiotic interaction, administration routes and dosing, and the development of phage resistance. The goal of this study was to develop a dual antibiotic-phage delivery system containing hydrogel and alginate microbeads loaded with a phage cocktail plus meropenem and evaluate efficacy against muti-drug resistant Pseudomonas aeruginosa. Two phages (FJK.R9-30 and MK.R3-15) displayed enhanced antibiotic activity against P. aeruginosa biofilms when tested in combination with meropenem. The antimicrobial activity of both antibiotic and phage was retained for eight days at 37 °C in dual phage and antibiotic loaded hydrogel with microbeads (PA-HM). In a mouse FRI model, phages were recovered from all tissues within all treatment groups receiving dual PA-HM. Moreover, animals that received the dual PA-HM either with or without systemic antibiotics had less incidence of phage resistance and less serum neutralization compared to phages in saline. The dual PA-HM could reduce bacterial load in soft tissue when combined with systemic antibiotics, although the infection was not eradicated. The use of alginate microbeads and injectable hydrogel for controlled release of phages and antibiotics, leads to the reduced development of phage resistance and lower exposure to the adaptive immune system, which highlights the translational potential of the dual PA-HM. However, further optimization of phage therapy and its delivery system is necessary to achieve higher bacterial killing activity in vivo in the future.

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.

[Antibiotic use for prophylaxis and empirical therapy of fracture-related infections in Germany : A survey of 44 hospitals]

BACKGROUND

Antibiotics play an important role in the prophylaxis and treatment of infections in orthopedic trauma surgery; however, there seems to be remarkable differences in the clinical antibiotic practice between hospitals, particularly for open fractures and for the empirical therapy of fracture-related infections (FRI).

METHODS

Therefore, we intended to evaluate the current clinical praxis in university and workers' compensation hospitals in Germany with a questionnaire on prophylaxis and empirical treatment of FRI. The results were compared with the resistance profile of 86 FRI patients in order to analyze the hypothetical effectiveness of the empirical treatment.

RESULTS

A total of 44 hospitals (62.0%) responded. A homogeneous antibiotic prophylaxis (95.5% of all hospitals) with cephalosporins was reported for perioperative prophylaxis of internal fixation of closed fractures. For open fractures, eight different monotherapy and combination treatment concepts were reported. In empirical treatment of FRI, 12 different therapeutic concepts were reported, including aminopenicillins/beta lactamase inhibitors (BLI) (31.8%), cephalosporins (31.8%), and ampicillin/sulbactam + vancomycin (9.1%). In terms of the hypothetical effectiveness of these antibiotic regimes, low sensitivity rates of 65.1% and 74.4% for cephalosporins and aminopenicillins/BLI, respectively, were found. For the combination vancomycin + meropenem, the highest hypothetical sensitivity (91.9%) was detected.

DISCUSSION

Based on the existing, institution-specific pathogen spectrum, the combination therapy including meropenem and vancomycin seems to be of value but should be restricted to patients with multiple revision procedures or a septic course of infection in order to prevent the selection of highly resistant pathogens.

Biodegradable Implants for Internal Fixation of Fractures and Accelerated Bone Regeneration

Bone fractures have always been a burden to patients due to their common occurrence and severe complications. Traditionally, operative treatments have been widely used in the clinic for implanting, despite the fact that they can only achieve bone fixation with limited stability and pose no effect on promoting tissue growth. In addition, the nondegradable implants usually need a secondary surgery for implant removal, otherwise they may block the regeneration of bones resulting in bone nonunion. To overcome the low degradability of implants and avoid multiple surgeries, tissue engineers have investigated various biodegradable materials for bone regeneration, whereas the significance of stability of long-term bone fixation tends to be neglected during this process. Combining the traditional orthopedic implantation surgeries and emerging tissue engineering, we believe that both bone fixation and bone regeneration are indispensable factors for a successful bone repair. Herein, we define such a novel idea as bone regenerative fixation (BRF), which should be the main future development trend of biodegradable materials.

Unraveling the New Perspectives on Antimicrobial Hydrogels: State-of-the-Art and Translational Applications

The growing impact of infections and the rapid emergence of antibiotic resistance represent a public health concern worldwide. The exponential development in the field of biomaterials and its multiple applications can offer a solution to the problems that derive from these situations. In this sense, antimicrobial hydrogels represent a promising opportunity with multiple translational expectations in the medical management of infectious diseases due to their unique physicochemical and biological properties as well as for drug delivery in specific areas. Hydrogels are three-dimensional cross-linked networks of hydrophilic polymers that can absorb and retain large amounts of water or biological fluids. Moreover, antimicrobial hydrogels (AMH) present good biocompatibility, low toxicity, availability, viscoelasticity, biodegradability, and antimicrobial properties. In the present review, we collect and discuss the most promising strategies in the development of AMH, which are divided into hydrogels with inherent antimicrobial activity and antimicrobial agent-loaded hydrogels based on their composition. Then, we present an overview of the main translational applications: wound healing, tissue engineering and regeneration, drug delivery systems, contact lenses, 3D printing, biosensing, and water purification.

Predictive factors for fracture-related infection in open tibial fractures in a Sub-Saharan African setting

INTRODUCTION

The management of open tibial fractures (OTF) is challenging in low and middle-income countries (LMICs) where appropriate human resources and infrastructure (including equipment, implants and surgical supplies) are not readily available and medical care is not readily accessible. OTF are not rarely associated with a subsequent fracture-related infection (FRI), which is one of the most devastating and difficult to cure complications in orthopaedic trauma care. The aim of this study was to determine the rate and the predictive factors of FRI in OTF in a limited-resource setting of sub-Saharan Africa.

METHODS

Patients with OTF who underwent surgery from July 2015 to December 2020 and followed-up for at least 12 months in a tertiary care teaching hospital in Yaoundé (Cameroon) were retrospectively investigated. Diagnosis of FRI was based on the confirmatory criteria of the International FRI Consensus definition. All patients with bone infections, occurring at any time point during follow-up, were included. Logistic regression was used to determine the predictive factors for FRI.

RESULTS

One hundred and five patients with OTF were studied. With a mean follow-up period of 29.5 ± 16.6 months, 33 patients (31.4%) presented with FRI. Gustilo-Anderson type of OTF, compliance with antibiotics, blood transfusion, time to first washing of the wounds and method of bone fixation were factors associated with the occurrence of FRI. In multivariable logistic regression, 6-hours delay to first washing of the wounds (OR=8.07, 95% CI: 1.43-45.31, p = 0.01), and compliance with antibiotics (OR=11.33, 95%CI: 1.11-115.6, p = 0.04) were the only independent predictors of FRI.

CONCLUSION

The overall rate of FRI in open tibial fracture is still high in the sub-Saharan African context. For similar low-resources settings, this study supports the recommendations (1) to perform a very early washing-dressing-splinting of OTF on admission of the patient, (2) to administer antibiotics early, and (3) to perform surgery as soon as reasonably possible, once appropriate personnel, equipment, implants and surgical supplies are available.

Hydrogel Delivery of DNase I and Liposomal Vancomycin to Eradicate Fracture-related Methicillin-resistant Staphylococcus aureus Infection and Support Osteoporotic Fracture Healing

Fracture-related infection (FRI) is a devastating complication in orthopedic surgery. A recent study showed that FRI causes more severe infection and further delays healing in osteoporotic bone. Moreover, bacterial biofilm formed on implants cannot be eradicated by systemic antibiotics, warranting novel treatments. Here, we developed a DNase I and Vancomycin hydrogel delivery vehicle to eradicate Methicillin-resistant Staphylococcus aureus (MRSA) infection in vivo. Vancomycin was encapsulated in liposomes, and DNase I and Vancomycin/liposomal-Vancomycin was loaded on thermosensitive hydrogel. In vitro drug release test showed a burst release of DNase I (77.2%) within 72 hours and sustained release of Vancomycin (82.6%) up to day 14. The in vivo efficacy was evaluated in a clinically relevant ovariectomy (OVX) induced osteoporotic metaphyseal fracture model with MRSA infection, and a total of 120 Sprague Dawley rats were used. In the OVX with infection group, biofilm development caused a drastic inflammatory response, trabecular bone destruction, and non-union. In the DNase I and Vancomycin co-delivery hydrogel group (OVX-Inf-DVG), bacteria on bone and implant were eradicated. X-ray and micro-CT showed preservation of trabecular bone and bone union. HE staining showed the absence of inflammatory necrosis, and fracture healing was restored. The local elevation of TNF-α and IL-6 and increased number of osteoclasts were prevented in the OVX-Inf-DVG group. Our findings suggest that dual release of DNase I and Vancomycin initially followed by Vancomycin only later up to 14 days effectively eliminates MRSA infection, prevents biofilm development and provides a sterile environment to promote fracture healing in osteoporotic bone with FRI. STATEMENT OF SIGNIFICANCE: The biofilm formation on the implant is difficult to eradicate, causing recurrent infection and non-union in fracture-related infection (FRI). Here we developed a hydrogel therapy with high in vivo efficacy to eliminate MRSA biofilm infection in a clinically-relevant FRI model in osteoporotic bone. By loading DNase I and vancomycin/liposomal-vancomycin on thermosensitive poly-(DL-lactic acidco-glycolic acid) (PLGA)-polyethylene glycol (PEG)-PLGA hydrogel, a dual release of DNase I and Vancomycin was achieved whilst preserving enzyme activity. In this model, the progressive development of infection caused a drastic inflammatory response, osteoclastogenesis, trabecular bone destruction, and non-union of fracture. These pathological changes were successfully prevented by the dual delivery of DNase I and vancomycin. Our findings provide a promising strategy for FRI in osteoporotic bone.

Antibiotic-loaded hydroxyapatite scaffolds fabricated from Nile tilapia bones for orthopaedics

This work aimed to develop new antibiotic-coated/ antibiotic-loaded hydroxyapatite (HAp) scaffolds for orthopaedic trauma, specifically to treat the infection after fixation of skeletal fracture. The HAp scaffolds were fabricated from the Nile tilapia (Oreochromis niloticus) bones and fully characterized. The HAp scaffolds were coated with 12 formulations of poly (lactic-co-glycolic acid) (PLGA) or poly (lactic acid) (PLA), blended with vancomycin. The vancomycin release, surface morphology, antibacterial properties, and the cytocompatibility of the scaffolds were conducted. The HAp powder contains elements identical to those found in human bones. This HAp powder is suitable as a starting material to build scaffolds. After the scaffold fabrication, The ratio of HAp to β-TCP changed, and the phase transformation of β-TCP to α-TCP was observed. All antibiotic-coated/ antibiotic-loaded HAp scaffolds can release vancomycin into the phosphate-buffered saline (PBS) solution. PLGA-coated scaffolds obtained faster drug release profiles than PLA-coated scaffolds. The low polymer concentration in the coating solutions (20%w/v) gave a faster drug release profile than the high polymer concentration (40%w/v). All groups showed a trace of surface erosion after being submerged in PBS for 14 days. Most of the extracts can inhibit Staphylococcus aureus (S. aureus) and methicillin-resistant S. aureus (MRSA). The extracts not only caused no cytotoxicity to Saos-2 bone cells but also can increase cell growth. This study demonstrates that it is possible to use these antibiotic-coated/ antibiotic-loaded scaffolds in the clinic as an antibiotic bead replacement.

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.

Silver Carboxylate-Eluting Titanium-Dioxide Polydimethylsiloxane Coating Inhibits Multi-Drug-Resistant Acinetobacterium baumannii and Vancomycin-Resistant Enterococcus faecalis Adherence and Proliferation on Orthopedic Trauma Fixation and Spinal Fusion Materials

Background: Vancomycin-resistant Enterococcus faecalis and multi-drug-resistant (MDR) Acinetobacter baumannii are rising contributors to spinal fusion and fracture-associated infections (FAI), respectively. These MDR bacteria can form protective biofilms, complicating traditional antibiotic treatment. This study explores the effects of the antibiotic-independent antimicrobial silver carboxylate (AgCar)-doped coating on the adherence sand proliferation of these pathogens on orthopedic implant materials utilized in spinal fusion and orthopedic trauma fixation. Methods: Multi-drug-resistant Acinetobacter baumannii and vancomycin-resistant Enterococcus faecalis were inoculated on five common implant materials: cobalt chromium, titanium, titanium alloy, polyether ether ketone, and stainless steel. Dose response curves were generated to assess antimicrobial potency. Scanning electron microscopy and confocal laser scanning microscopy were utilized to characterize and quantify growth and adherence on each material. Results: The optimal AgCar concentration was a 95% titanium dioxide (TiO₂)-5% polydimethylsiloxane (PDMS) matrix combined with 10 × silver carboxylate, which inhibited bacterial proliferation by 89.40% (p = 0.001) for MDR Acinetobacter baumannii and 84.02% (p = 0.001) for vancomycin-resistant Enterococcus faecalis compared with uncoated implants. A 95% TiO₂-5% PDMS matrix combined with 10 × AgCar was equally effective at inhibiting bacterial proliferation across all implant materials for MDR Acinetobacter baumannii (p = 0.19) and vancomycin-resistant Enterococcus faecalis (p = 0.07). A 95% TiO2-5% PDMS matrix with 10 × AgCar is effective at decreasing bacterial adherence of both MDR Acinetobacter baumannii and vancomycin-resistant Enterococcus faecalis on implant materials. Conclusions: Application of this antibiotic-independent coating for surgery in which these implant materials might be used may prevent adherence, biofilm formation, spinal infections, and FAI by MDR Acinetobacter baumannii and vancomycin-resistant Enterococcus faecalis.

Antimicrobial potency, prevention ability, and killing efficacy of daptomycin-loaded versus vancomycin-loaded β-tricalcium phosphate/calcium sulfate for methicillin-resistant Staphylococcus aureus biofilms

Growing evidence has shown that the efficacy of systemic administration of daptomycin for the treatment of methicillin-resistant Staphylococcus aureus (MRSA)-related infections is satisfactory. However, the clinical efficacy of the local administration of daptomycin for the management of osteoarticular infections remains unclear. This in vitro study compared the efficacy of daptomycin and vancomycin against MRSA biofilms. The elution kinetics of daptomycin and vancomycin, combined with gentamicin and loaded with either β-tricalcium phosphate/calcium sulfate or calcium sulfate, in the presence of MRSA infection, was assessed. Their efficacy in preventing biofilm formation and killing pre-formed biofilms was assessed using colony-forming unit count and confocal laser scanning microscopy. In addition, the efficacy of daptomycin, vancomycin, and gentamicin in prophylaxis and eradication of MRSA biofilms was also evaluated. Daptomycin + gentamicin and vancomycin + gentamicin displayed similar antimicrobial potency against MRSA, by either β-tricalcium phosphate/calcium sulfate or calcium sulfate. In the prevention assays, both daptomycin + gentamicin and vancomycin + gentamicin showed similar efficacy in preventing bacterial colony formation, with approximately 6 logs lower colony-forming units than those in the control group at both 1 and 3  days. The killing effect on pre-formed biofilms showed significant decreases of approximately 4 logs at 1 and 3  days following treatment with daptomycin + gentamicin and vancomycin + gentamicin. In addition, the confocal laser scanning microscopy results support the colony-forming unit data. Moreover, single use of vancomycin and gentamicin showed similar efficacies in preventing and killing MRSA biofilms, both of which were better than that of gentamicin. Our study demonstrated that vancomycin + gentamicin and daptomycin + gentamicin loaded with β-tricalcium phosphate/calcium sulfate or calcium sulfate showed similar prophylactic and killing effects on MRSA biofilms, implying a potential indication of local administration daptomycin for the treatment of MRSA-associated osteoarticular infections, especially if vancomycin administration presents limitations.

Fracture-Related Infection in Bicolumnar Acetabular Fracture: A Case Report

Case: A 51-year-old man was affected by a fracture-related infection after a bicolumnar acetabular fracture. A significant alteration of the anatomy was present; thus, a 3D-printed model was useful for planning. A two-stage treatment was planned: in the first stage, implant removal with irrigation and debridement was performed, while in the second stage, a new osteosynthesis and implant of a THA were planned. During the second stage, the patient suffered a cardiogenic shock, so a third surgical procedure was necessary to implant THA. Targeted antibiotic therapy was administered eight weeks after the first stage, with the resolution of the infection. Conclusions: The infection was resolved following the recent guidelines and treating it like a periprosthetic infection with a two-stage revision. A collaboration between specialists in orthopaedics and infectious disease, respectively, and using multidisciplinary approach, were mandatory.

Repair of Large-Scale Rib Defects Based on Steel-Reinforced Concrete-Designed Biomimetic 3D-Printed Scaffolds with Bone-Mineralized Microenvironments

Tissue engineering technology provides a promising approach for large-scale bone reconstruction in cases of extensive chest wall defects. However, previous studies did not consider meticulous scaffold design specific to large-scale rib regeneration in terms of three-dimensional (3D) shape, proper porous structures, enough mechanical strength, and osteogenic microenvironments. Thus, there is an urgent need to develop an appropriate bone biomimetic scaffold (BBS) to address this problem. In this study, a BBS with controllable 3D morphology, appropriate mechanical properties, good biocompatibility and biodegradability, porous structure suitable for cell loading, and a biomimetic osteogenic inorganic salt (OIS) microenvironment was successfully prepared by integrating computer-aided design, 3D-printing, cast-molding, and freeze-drying technologies. The addition of the OIS in the scaffold substantially promoted ectopic bone regeneration in vivo, which might be attributed to the activation of osteogenic and angiogenic signaling pathways as well as upregulated expression of osteogenic genes. More importantly, dual long rib defects could be successfully repaired and medullary cavity recanalized by the rib-shaped mature cortical bone, which might be mediated by the activation of osteoclast signaling pathways. Thus, this paper presents a reliable BBS and proposes a new strategy for the repair of large-scale bone defects.

Epidemiology and Drug Resistance of Fracture-Related Infection of the Long Bones of the Extremities: A Retrospective Study at the Largest Trauma Center in Southwest China

Objective

To describe the demographic characteristics, risk factors, and bacterial resistance of fracture-related infection (FRI) of the long bones of the extremities.

Materials and Methods

This single-center study retrospectively evaluated patients with FRI of the long bones of the extremities at West China Hospital between January 2012 and December 2017, and analyzed the demographic characteristics, risk factors, distribution of pathogenic bacteria, and bacterial drug resistance.

Results

Among 9,900 patients, 535 patients (5.4%) were diagnosed with FRI. The most common site of FRI was tibiofibular (298, 55.7%), with 424 cases (79.2%) of open fractures, and 282 cases (52.7%) due to traffic injuries. The 41–50 years age group had the highest incidence of FRI with 157 (29.3%) cases. Overall, 546 strains of 52 types of bacteria were detected in FRI patients, with 105 strains of multidrug-resistant (MDR) bacteria. Methicillin-resistant Staphylococcus aureus (48, 8.8%) and extended-spectrum-β-lactamase Escherichia coli (32, 5.8%) accounted for the largest proportion. Multivariate logistic regression analysis showed that sex (odds ratio [OR] 1.813; 95% confidence interval [CI], 1.071∼3.070; P = 0.027) and fracture type (OR 3.128; 95% CI, 1.683∼5.815; P < 0.001) were independent risk factors for monomicrobial infection (MI). Female sex (OR 4.190; 95% CI, 1.212∼14.486; P = 0.024) was an independent risk factor for polymicrobial infection (PI).

Conclusion

This study clarified the infection rates, changes in the bacterial spectrum, and drug resistance characteristics, and risk factors of FRI of the long bones of the extremities in the largest trauma center in southwest China.

The Microbiological Etiology of Fracture-Related Infection

Purpose

Fracture-related infection (FRI) is an important complication related to orthopaedic trauma. Although the scientific interest with respect to the diagnosis and treatment of FRI is increasing, data on the microbiological epidemiology remains limited. Therefore, the primary aim of this study was to evaluate the microbiological epidemiology related to FRI, including the association with clinical symptoms and antimicrobial susceptibility data. The secondary aim was to analyze whether there was a relationship between the time to onset of infection and the microbiological etiology of FRI.

Methods

FRI patients treated at the University Hospitals of Leuven, Belgium, between January 1st 2015 and November 24th 2019 were evaluated retrospectively. The microbiological etiology and antimicrobial susceptibility data were analyzed. Patients were classified as having an early (<2 weeks after implantation), delayed (2-10 weeks) or late-onset (> 10 weeks) FRI.

Results

One hundred ninety-one patients with 194 FRIs, most frequently involving the tibia (23.7%) and femur (18.6%), were included. Staphylococcus aureus was the most frequently isolated pathogen, regardless of time to onset (n=61; 31.4%), followed by S. epidermidis (n=50; 25.8%) and non-epidermidis coagulase-negative staphylococci (n=35; 18.0%). Polymicrobial infections (n=49; 25.3%), mainly involving Gram negative bacilli (GNB) (n=32; 65.3%), were less common than monomicrobial infections (n=138; 71.1%). Virulent pathogens in monomicrobial FRIs were more likely to cause pus or purulent discharge (n=45;54.9%; p=0.002) and fistulas (n=21;25.6%; p=0.030). Susceptibility to piperacillin/tazobactam for GNB was 75.9%. Vancomycin covered 100% of Gram positive cocci.

Conclusion

This study revealed that in early FRIs, polymicrobial infections and infections including Enterobacterales and enterococcal species were more frequent. A time-based FRI classification is not meaningful to estimate the microbiological epidemiology and cannot be used to guide empiric antibiotic therapy. Large multicenter prospective studies are necessary to gain more insight into the added value of (broad) empirical antibiotic therapy.

Prior use of antibiotics and immunosuppression are risk factors for fracture-related infection during the COVID-19 pandemic period: a Brazilian prospective cohort study

Background

Little is known about the role of COVID-19 pandemic period on the epidemiology of fracture-related infection (FRI). The present study summarizes the changes in the prevalence, microbiology, and risk factors of FRI during this period.

Methods

A prospective single-center cohort study assessed in the setting of COVID-19 pandemic (2020–2021), clinical, microbiological aspects, and independent risk factors (RF) of FRI. RFs were estimated by bivariate and multivariable analyses using prevalence ratio (PR) with significance at P < 0.05. Kaplan–Meier analysis was performed to evaluate treatment outcomes.

Results

Overall, 132 patients were analyzed, with patients with age over 65 years accounting 65.1%. FRI was diagnosed in 21(15.9%) patients. Independent RFs for FRI were recent and preoperative use of systemic antibiotics (PR: 7.0, 95% confidence interval (95% CI): 2.2 – 22.4, p = 0.001) and cancer (PR: 9.8, 95% CI: 2.0 – 48.8, p = 0.005). Cultures yielded Gram-negative bacteria in 77.8%, 33.3% were MDR.

Conclusions

We found higher rates of FRI, predominating in the elderly with closed femoral fractures during the COVID-19 pandemic. Prior use of antibiotics and immunosuppression conditions were independent factor for FRI. Our outcomes provide evidence to avoid the empirical use of antibiotics prior to surgery for fracture stabilization.

An Antibiotic-Loaded Hydrogel Demonstrates Efficacy as Prophylaxis and Treatment in a Large Animal Model of Orthopaedic Device-Related Infection

Local antibiotic therapy is increasingly being recognised for its role in preventing and treating orthopaedic device-related infection (ODRI). A bioresorbable, injectable gentamicin-loaded hydrogel has been developed to deliver local antibiotics at the time of surgery with potential for both prevention and treatment of ODRI. In a prophylaxis model, the antibiotic hydrogel was compared with systemic perioperative antibiotic prophylaxis alone in twelve sheep (six per group) at the time of intramedullary (IM) nail insertion to the tibia, which was inoculated with methicillin-sensitive Staphylococcus aureus (MSSA). In a treatment model of single-stage revision surgery, adjunctive antibiotic-loaded hydrogel was compared with systemic antibiotics alone in a single stage revision of MSSA infection associated with a tibia intramedullary nail in eleven sheep (five/six per group). The primary endpoint was quantitative microbiological results of soft tissue, bone and sonicate fluid from explanted hardware at the time of euthanasia. At euthanasia, the control sheep that received no local antibiotics in the prophylaxis model were all culture-positive (median 1x10⁸, range 7x10⁶-3x10⁸ colony forming units, CFU) while only two of six sheep receiving local gentamicin had any culture positive biopsies (median 1x10¹, range 0 - 1x10⁵ CFU). For the treatment model, sheep receiving only systemic antibiotics were all culture-positive (median 8x10⁵, range 2x10³- 9x10⁶ CFU) while only two of six sheep treated with gentamicin-loaded hydrogel had any culture positive biopsies (median 3x10², range 0 - 7x10⁴ CFU). Local gentamicin concentrations measured in extracellular fluid in the tibial canal show a burst release of gentamicin from the hydrogel. Serum gentamicin concentrations peaked in both models at one day post application and were below detection limit thereafter. This study has demonstrated the effective use of a locally delivered antibiotic hydrogel for both the prevention and treatment of ODRI that is superior to that of systemic antibiotics alone. Future studies will endeavour to translate from preclinical to clinical research trials.

Type of antibiotic but not the duration of prophylaxis correlates with rates of fracture-related infection

PURPOSE

The issue of optimal prophylactic antibiotic administration for closed and open fracture surgeries remains controversial. The purpose of this study was to assess the role of type and duration longer than 48 h of antibiotic prophylaxis on the rates of fracture-related infection (FRI).

METHODS

This is a single-center, prospective observational cohort study carried out with patients undergoing surgery for implants insertion to fracture stability. Risk estimates were calculated on the variables associated with factors for FRI and reported as a prevalence ratio (PR) with respect to the 95% confidence interval (CI).

RESULTS

Overall, 132 patients were analyzed. The global rate of FRI was 15.9% (21/132), with open and closed fractures accounting for 30.5% (11/36) and 10.4% (10/96), respectively. The FRI rates in patients undergoing orthopedic surgery for fracture stabilization who received prophylactic antibiotic for up to and longer than 48 h were 8.9% and 26.4%, respectively. This difference did not reach statistical significance (prevalence ratio [PR] = 2.6, 95% confidence interval [95% CI]: 0.9-7.3. p = 0.063).

CONCLUSIONS

Duration of antibiotic prophylaxis for surgical orthopedic fractures was not correlated with rates of FRI.

What Is the Most Effective Empirical Antibiotic Treatment for Early, Delayed, and Late Fracture-Related Infections?

Antibiotic treatment strategies for fracture-related infections (FRI) are often extrapolated from periprosthetic joint infections (PJI), although, in contrast to PJI, detailed analysis of pathogens and their antibiotic resistance is missing. Therefore, this study aimed to investigate antibiotic susceptibility profiles to identify effective empiric antibiotic treatment for early-, delayed-, and late-onset FRI. Patients treated for FRI from 2013 to 2020 were grouped into early (<2 weeks), delayed (3−10 weeks), and late (>10 weeks) onset of infection. Antibiotic susceptibility profiles were examined with respect to broadly used antibiotics and antibiotic combinations. In total, 117 patients (early n = 19, delayed n = 60, late n = 38) were enrolled. In early-onset FRI, 100.0% efficacy would be achieved by meropenem + vancomycin, gentamicin + vancomycin, co-amoxiclav + glycopeptide, ciprofloxacin + glycopeptide and piperacillin/tazobactam + glycopeptide. For patients with delayed FRI, the highest susceptibility was revealed for meropenem + vancomycin, gentamicin + vancomycin and ciprofloxacin + glycopeptide (96.7%). Meropenem + vancomycin was the most effective empiric antimicrobial in patients with late-onset of infection with 92.1% coverage. No subgroup differences in antibiotic sensitivity profiles were observed except for the combination ciprofloxacin + glycopeptide, which was significantly superior in early FRI (F = 3.304, p = 0.04). Across all subgroups meropenem + vancomycin was the most effective empiric treatment in 95.7% of patients with confirmed susceptibility. Meropenem + vancomycin, gentamicin + vancomycin, co-amoxiclav + glycopeptide are the best therapeutic options for FRI, regardless of the onset of infection. To avoid multidrug resistance, established antibiotic combinations such as co-amoxiclav with a glycopeptide seem to be reasonable as a systemic antibiotic therapy, while vancomycin + gentamicin could be implemented in local antibiotic therapy to reduce adverse events during treatment.

Effectiveness of an Online Course on Fracture-Related Infections

This study aims to evaluate the effectiveness of an online course to enable orthopaedic surgeons to acquire the core competencies necessary to prevent and treat fracture-related infections (FRI). This study included orthopaedic surgeons and residents from Latin American countries who attended an online course focused on FRI. The online course included: didactic lectures, small-group clinical case discussions, and panel case discussions. The course was delivered using Zoom® platform and designed to address four core competencies: prevention, definition and diagnosis, antimicrobial therapy, and surgical treatment. An online questionnaire was created distributing 16 questions through six clinical scenarios. Participants were invited to answer the questionnaire before and after the course. Sixty of the 78 course participants answered the pre-course, and 42 the post-course assessment. Relative to before the course, the mean post-course assessment score rose significantly for prevention of FRI (4.1 before and 4.5 after; p = 0.014), definition and diagnosis (2.4 before and 3.4 after; p = 0.001), and surgical treatment (2.2 before and 2.8 after; p = 0.011). The final score encompassing all four core competencies also rose significantly (2.7 before and 3.3 after; p = 0.001). The online course on FRI was feasible and effective, significantly increasing course users’ knowledge of overall competency in managing FRI.

[Management of fracture-related infections]

Fracture-related infections (FRI) are a major challenge in orthopedic trauma surgery. The problems in the treatment of such infections are manifold. Especially in cases with insufficient fracture consolidation the treatment not only focusses on the eradication of the infection but also on the restoration of the osseous continuity. The extent of the accompanying soft tissue damage is of particular importance as reduced vascularization leads to impairments in fracture healing. Although acute infections are frequently easy to recognize, the symptoms of chronic infections can be unspecific and evade the diagnostic procedures. This fact makes the treatment of such infections complicated and sometimes necessitates an interdisciplinary approach. For this reason, the Fracture-related Infection Consensus Group developed an algorithm, which was first published in 2017 and revised in 2018 and 2020. The FRIs are biofilm-associated infections, so that the current guidelines follow the previously established treatment algorithms for periprosthetic infections. Despite the analogies to periprosthetic infections there are also differences in the treatment as the aspects of fracture healing and bone defect restoration represent determining factors in the treatment of FRI. This article presents the special features of FRI and the classification and guidelines for the treatment are discussed.

Facilitating the Approval Process of Anti-Infective Technologies and Advancing Them to the Market: Insights from an FDA Workshop on Orthopaedic Device-Related Infections

Orthopaedic device-related infection is one of the most devastating complications in orthopaedic and trauma surgery. With increasing life expectancies as well as the lifelong risk of bacterial seeding on an implant, the prevention and treatment of device-related infection remains an important area for research and development. To facilitate information exchange and enhance collaboration among various stakeholders in the orthopaedic community, the U.S. Food and Drug Administration (FDA) Center for Devices and Radiological Health (CDRH) organized an inaugural workshop on orthopaedic device-related infections, exploring the regulatory challenges that are faced when proceeding from the bench level to marketing and clinical implementation of new infection-control devices and products. This article summarizes the perspectives of scientists, clinicians, and industry partners on the current regulatory approval process for orthopaedic anti-infective technologies as well as the proposed strategies to overcome these regulatory challenges.

Diagnosing fracture related infections: Where are we now?

Accurate diagnosis of fracture related infection (FRI) is critical for preventing poor outcomes such as loss of function or amputation. Due to the multiple variables associated with FRI, however, accurate diagnosis is challenging and complicated by a lack of standardized diagnostic criteria. Limitations with the current gold standard for diagnosis, which is routine microbiology culture, further complicate the diagnostic and management process. Efforts to optimize the process rely on a foundation of data derived from prosthetic joint infections (PJI), but differences in PJI and FRI make it clear that unique approaches for these distinct infections are required. A more concerted effort focusing on FRI has dominated more recent investigations and publications leading to a consensus definition by the American Orthopedics (AO) Foundation and the European Bone and Joint Infection Society (EBJIS). This has the potential to better standardize the diagnostic process, which will not only improve patient care but also facilitate more robust and reproducible research related to the diagnosis and management of FRI. The purpose of this review is to explore the consensus definition, describe the foundation of data supporting current FRI diagnostic techniques, and identify pathways for optimization of clinical microbiology-based strategies and data.

Cutibacterium acnes in shoulder surgery: a scoping review of strategies for prevention, diagnosis, and treatment

BACKGROUND

Cutibacterium acnes is a commensal, gram-positive, facultatively anaerobic bacillus that resides in the dermis. Historically thought to be a contaminant when identified on cultured specimens, recent advances in diagnostic technology have now implicated it as the most common organism responsible for postoperative shoulder infections. Despite a recognition of the role of this organism and a significant research interest in recent years, there is clear lack of consensus guideline on strategies to prevent, diagnose, and treat postoperative shoulder infection.

METHOD

The electronic databases PubMed, MEDLINE, CINAHL, Scopus, and Web of Science were searched in March 2020. All experimental and nonexperimental studies that investigate C acnes in shoulder surgery were included. Inclusion was limited to articles published after 2000 and written in English; reviews, gray literature, or abstracts were excluded. A total of 70 studies were included in this review. This scoping review was performed in accordance with the Extended Preferred Reporting Items of Systematic Reviews and Meta-Analyses Statement for Scoping Reviews (PRISMA-ScR).

RESULTS

Standard surgical prophylactic regimens such as intravenous antibiotics and topical chlorhexidine are ineffective at removing C acnes from the deep layer of the dermis, and there is a shift toward using topical benzoyl peroxide with significantly improved efficacy. An improved understanding of the bacteria has demonstrated that a prolonged culture time of up to 14 days is needed, especially in cases of established infection. Advances in diagnostics such as sonication and molecular-based testing are promising. Although usually thought to be susceptible to a broad range of antibiotics, resistance is emerging to clindamycin. An improved understanding of its ability to form a biofilm highlights the difficulty in treating an established infection.

CONCLUSION

The role of C acnes causing postoperative infection following shoulder surgery is being increasingly recognized. Strategies for prevention, diagnosis, and treatment have been outlined from both an antimicrobial and surgical perspective. A number of these strategies are emerging and require further research to demonstrate efficacy before implementation into clinical guidelines.

The epidemiology of fracture-related infections in Germany

The epidemiology of fracture-related infection (FRI) is unknown, which makes it difficult to estimate future demands and evaluate progress in infection prevention. Therefore, we aimed to determine the nationwide burden’s development over the last decade as a function of age group and gender. FRI prevalence as a function of age group and gender was quantified based on annual ICD-10 diagnosis codes from German medical institutions between 2008 through 2018, provided by the Federal Statistical Office of Germany (Destatis). The prevalence of FRI increased by 0.28 from 8.4 cases per 100,000 inhabitants to 10.7 cases per 100,000 inhabitants between 2008 and 2018. The proportion of fractures resulting in FRI increased from 1.05 to 1.23%. Gender distribution was equal. Patients aged 60–69 years and 70–79 years comprised the largest internal proportion with 20.2% and 20.7%, respectively, whereby prevalence increased with age group. A trend towards more diagnoses in older patients was observed with a growth rate of 0.63 for patients older than 90 years. Increasing rates of fracture-related infection especially in older patients indicate an upcoming challenge for stakeholders in health care systems. Newly emerging treatment strategies, prevention methods and interdisciplinary approaches are strongly required.

Long-term patient-related quality of life after fracture-related infections of the long bones

Aims

We aimed to evaluate the long-term impact of fracture-related infection (FRI) on patients’ physical health and psychological wellbeing. For this purpose, quality of life after successful surgical treatment of FRIs of long bones was assessed.

Methods

A total of 37 patients treated between November 2009 and March 2019, with achieved eradication of infection and stable bone consolidation after long bone FRI, were included. Quality of life was evaluated with the EuroQol five-dimension questionnaire (EQ-5D) and German Short-Form 36 (SF-36) outcome instruments as well as with an International Classification of Diseases of the World Health Organization (ICD)-10 based symptom rating (ISR) and compared to normative data.

Results

With a mean follow-up of 4.19 years (SD 2.7) after the last surgery, the mean SF-36 score was 40.1 (SD 14.6) regarding the physical health component and 48.7 (SD 5.1) regarding the mental health component, compared to German normative values of 48.4 (SD 9.2) (p < 0.001) and 50.9 (SD 8.8) (p = 0.143). The mean EQ-5D index reached 0.76 (SD 0.27) with a mean EQ-5D visual analogue scale (VAS) rating of 65.7 (SD 22.7) compared to reference scores of 0.88 (p < 0.001) and 72.9 (p < 0.001). Mean scores of the ISR did not reveal significant psychological symptom burden, while an individual analysis showed moderate to severe impairments in 21.6% (n = 8) of the patients.

Conclusion

Even a mean 4.2 years (SD 2.7) after surgically successful treatment of FRI of long bones, patients report significantly lower quality of life in comparison to normative data. Future clinical studies on FRIs should focus on patient-related outcome measures enabling best possible shared treatment decision-making. Prevention methods and interdisciplinary approaches should be implemented to improve the overall quality of life of FRI patients.

Cite this article: Bone Joint Res 2021;10(5):321–327.

A Hyaluronic Acid Hydrogel Loaded with Gentamicin and Vancomycin Successfully Eradicates Chronic Methicillin-Resistant Staphylococcus aureus Orthopedic Infection in a Sheep Model

Implantable orthopedic devices have had an enormously positive impact on human health; however, despite best practice, patients are prone to developing orthopedic device-related infections (ODRI) that have high treatment failure rates. One barrier to the development of improved treatment options is the lack of an animal model that may serve as a robust preclinical assessment of efficacy. We present a clinically relevant large animal model of chronic methicillin-resistant Staphylococcus aureus (MRSA) ODRI that persists despite current clinical practice in medical and surgical treatment at rates equivalent to clinical observations. Furthermore, we showed that an injectable, thermoresponsive, hyaluronic acid-based hydrogel loaded with gentamicin and vancomycin outperforms current clinical practice treatment in this model, eliminating bacteria from all animals. These results confirm that local antibiotic delivery with an injectable hydrogel can dramatically increase treatment success rates beyond current clinical practice, with efficacy proven in a robust animal model.

Single-stage revision of MRSA orthopedic device-related infection in sheep with an antibiotic-loaded hydrogel

Local antimicrobial therapy is an integral aspect of treating orthopedic device-related infection (ODRI), which is conventionally administered via polymethyl-methacrylate (PMMA) bone cement. PMMA, however, is limited by a suboptimal antibiotic release profile and a lack of biodegradability. In this study, we compare the efficacy of PMMA versus an antibiotic-loaded hydrogel in a single-stage revision for chronic methicillin-resistant Staphylococcus aureus (MRSA) ODRI in sheep. Antibiofilm activity of the antibiotic combination (gentamicin and vancomycin) was determined in vitro. Swiss alpine sheep underwent a single-stage revision of a tibial intramedullary nail with MRSA infection. Local gentamicin and vancomycin therapy was delivered via hydrogel or PMMA (n = 5 per group), in conjunction with systemic antibiotic therapy. In vivo observations included: local antibiotic tissue concentration, renal and liver function tests, and quantitative microbiology on tissues and hardware post-mortem. There was a nonsignificant reduction in biofilm with an increasing antibiotic concentration in vitro (p = 0.12), confirming the antibiotic tolerance of the MRSA biofilm. In the in vivo study, four out of five sheep from each treatment group were culture-negative. Antibiotic delivery via hydrogel resulted in 10-100 times greater local concentrations for the first 2-3 days compared with PMMA and were comparable thereafter. Systemic concentrations of gentamicin were minimal or undetectable in both groups, while renal and liver function tests were within normal limits. This study shows that a single-stage revision with hydrogel or PMMA is equally effective, although the hydrogel offers certain practical benefits over PMMA, which make it an attractive proposition for clinical use.

Antibiotic loaded β-tricalcium phosphate/calcium sulfate for antimicrobial potency, prevention and killing efficacy of Pseudomonas aeruginosa and Staphylococcus aureus biofilms

This study investigated the efficacy of a biphasic synthetic β-tricalcium phosphate/calcium sulfate (β-TCP/CS) bone graft substitute for compatibility with vancomycin (V) in combination with tobramycin (T) or gentamicin (G) evidenced by the duration of potency and the prevention and killing efficacies of P. aeruginosa (PAO1) and S. aureus (SAP231) biofilms in in vitro assays. Antibiotic loaded β-TCP/CS beads were compared with antibiotic loaded beads formed from a well characterized synthetic calcium sulfate (CS) bone void filler. β-TCP/CS antibiotic loaded showed antimicrobial potency against PAO1 in a repeated Kirby-Bauer like zone of inhibition assay for 6 days compared to 8 days for CS. However, both bead types showed potency against SAP231 for 40 days. Both formulations loaded with V + T completely prevented biofilm formation (CFU below detection limits) for the 3 days of the experiment with daily fresh inoculum challenges (P < 0.001). In addition, both antibiotic loaded materials and antibiotic combinations significantly reduced the bioburden of pre-grown biofilms by between 3 and 5 logs (P < 0.001) with V + G performing slightly better against PAO1 than V + T. Our data, combined with previous data on osteogenesis suggest that antibiotic loaded β-TCP/CS may have potential to stimulate osteogenesis through acting as a scaffold as well as simultaneously protecting against biofilm infection. Future in vivo experiments and clinical investigations are warranted to more comprehensively evaluate the use of β-TCP/CS in the management of orthopaedic infections.