Current opinions on the mechanism, classification, imaging diagnosis and treatment of post-traumatic osteomyelitis

Staphylococcus aureus in Inflammation and Pain: Update on Pathologic Mechanisms

Staphylococcus aureus (S. aureus) is a Gram-positive bacterium of significant clinical importance, known for its versatility and ability to cause a wide array of infections, such as osteoarticular, pulmonary, cardiovascular, device-related, and hospital-acquired infections. This review describes the most recent evidence of the pathogenic potential of S. aureus, which is commonly part of the human microbiota but can lead to severe infections. The prevalence of pathogenic S. aureus in hospital and community settings contributes to substantial morbidity and mortality, particularly in individuals with compromised immune systems. The immunopathogenesis of S. aureus infections involves intricate interactions with the host immune and non-immune cells, characterized by various virulence factors that facilitate adherence, invasion, and evasion of the host's defenses. This review highlights the complexity of S. aureus infections, ranging from mild to life-threatening conditions, and underscores the growing public health concern posed by multidrug-resistant strains, including methicillin-resistant S. aureus (MRSA). This article aims to provide an updated perspective on S. aureus-related infections, highlighting the main diseases linked to this pathogen, how the different cell types, virulence factors, and signaling molecules are involved in the immunopathogenesis, and the future perspectives to overcome the current challenges to treat the affected individuals.

Management and Long-Term Outcomes of Post-traumatic Chronic Osteomyelitis in Long Bones: Cierny-Mader Types III and IV

Background This study describes the long-term clinical and functional outcomes of patients with post-traumatic Cierny-Mader (C-M) Type III and IV chronic osteomyelitis (CO), managed by considering individual patient differences. Methods Twenty patients who developed CO of the long bones after trauma were included in this study. Data on the demographic characteristics of the patients, clinical and radiological characteristics, and surgical methods applied were collected. The classification system defined by C-M was used for CO classification. The Short Form-36 (SF-36) quality of life scale was used to evaluate the functional outcomes and quality of life of the patients at the end of follow-up. Results The participants included 16 males and four females, with an average age of 39.3 ± 14.5 years. The mean duration of CO was 6.8 ± 7.5 years. The anatomical location of the CO was in the tibia in 15 patients, in the femur in four, and in the radius in one. The mean follow-up time after CO reconstruction was 4.5 ± 1.05 years. According to the C-M anatomical classification, there were nine patients with Type III and 11 with Type IV. According to the C-M physiological classification, there was one patient with Class A, 16 with Class B1, and three with Class B2. Different combinations of surgical procedures were performed on each patient. The average number of surgical interventions performed on the patients was 3.1 ± 1.1. Culture growth was detected in 13 patients. At the end of follow-up, the patients' SF-36 scores were lower than those in the normal population. Conclusion Due to the varied histories of CO and individual differences, it is quite challenging to plan a standard treatment procedure for CO in clinical practice. Successful treatment can be achieved with a long-term multidisciplinary approach and individualized, well-planned treatment methods.

The Masquelet technique triggers the formation of a network involving LncRNA, circRNA, miRNA, and mRNA during bone repair

BACKGROUND

The ceRNA network, which is competitive endogenous RNA, uncovers a fresh mechanism of RNA interaction and holds significant importance in diverse biological processes. The aim of this study is to investigate the molecular process of induced membrane (IM) formation in bone defects using the Masquelet's induced membrane technique (MIMT), in order to offer novel insights and a theoretical foundation for enhancing the treatment of bone defects with MIMT.

METHODS

In this work, we identified differentially expressed mRNAs (DEGs), lncRNAs (DELs), circRNAs (DECs), and miRNAs (DEMs). To explore the primary functions of the shared DEGs, we utilized Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. Next, predictions were made for lncRNA-miRNA and miRNA-mRNA interactions, and the Cytoscape software was utilized to construct the regulatory network for ceRNA.

RESULTS

By integrating GO and KEGG enrichment analysis, a total of 385 differentially expressed genes (DEGs) were discovered in the samples from the MIMT-treated group. Additionally, after re-annotating the probes and intersecting two sets of differently expressed miRNAs, 1304 differentially expressed lncRNAs (DELs) and 23 differentially expressed circRNAs (DECs) were identified. Furthermore, 13 differentially expressed miRNAs (DEMs) were obtained. Moreover, utilizing the anticipated objectives of DEMs, we acquired 1203 pairs of lncRNA-miRNA-mRNA interactors (comprising 24 lncRNAs, 10 miRNAs, and 115 mRNAs) and 250 pairs of circRNA-miRNA-mRNA interactions (comprising 7 circRNAs, 9 miRNAs, and 115 mRNAs). CEBPA, DGAT2, CDKN1A, PLIN2, and CIDEC were identified as the five hub proteins in the PPI network. LncRNA/circRNA-hsa-miR-671-5p could potentially regulate the primary central protein, CEBPA.

CONCLUSIONS

In this study, we described the potential regulatory mechanism of the MIMT in treating bone defects. We proposed a new lncRNA-miRNA-mRNA ceRNA network that could help further explore the molecular mechanisms of bone repair.

Post-traumatic extensive chronic osteomyelitis of skull vault: An illustrative case report

Chronic osteomyelitis of the skull base is a commonly reported pathology in existing scientific literature, but chronic osteomyelitis of the skull vault (COSV) is a rarely documented disease. We report the case of a 38 years old Afghan male with a presenting complaint of irregular swelling on the skull vault for six months. The patient had a history of head trauma one year back with a compound depressed fracture which had been surgically managed then. Physical examination revealed a 15 x 15 cm hard, immobile swelling with an old scar mark over the scalp. Neuroimaging was consistent with diffuse, bilateral frontoparietal swelling of bony origin, sparing underlying brain parenchyma. Surgically excision of the lesion was done through a bicoronal skin flap and cranioplasty done at the same time. Histological findings of the specimen reported chronic osteomyelitis. However, microbiology revealed no growth in culture. Patient was discharged on the second postoperative day uneventfully. This case turns minds into keeping skull vault osteomyelitis as differential diagnosis besides other spontaneous bony lesions; e.g. fibrous dysplasia, osteoma and giant cell tumours.

Nicotine promotes Staphylococcus aureus-induced osteomyelitis by activating the Nrf2/Slc7a11 signaling axis

Although smoking is a significant risk factor for osteomyelitis, there is limited experimental evidence that nicotine, a key tobacco constituent, is associated with this condition, leaving its mechanistic implications uncharacterized. This study revealed that nicotine promotes Staphylococcus aureus-induced osteomyelitis by increasing Nrf2 and Slc7a11 expression in vivo and in vitro. Inhibition of Slc7a11 using Erastin augmented bacterial phagocytosis/killing capabilities and fortified antimicrobial responses in an osteomyelitis model. Moreover, untargeted metabolomic analysis demonstrated that Erastin mitigated the effects of nicotine on S. aureus-induced osteomyelitis by altering glutamate/glutathione metabolism. These findings suggest that nicotine aggravates S. aureus-induced osteomyelitis by activating the Nrf2/Slc7a11 signaling pathway and that Slc7a11 inhibition can counteract the detrimental health effects of nicotine.

Comparison of diagnostic efficacy between 99mTc-methylene diphosphate SPECT/CT and MRI for bone and joint infections: a multicenter retrospective analysis

Objective

There is currently no non-invasive examination that can fully determine the diagnosis of osteomyelitis. SPECT/CT tomographic fusion imaging can provide both local metabolic activity and anatomical information to determine the condition and location. This study evaluates the diagnostic efficacy of 99mTc-MDP SPECT/CT in bone infections, compared to MRI.

Methods

In this multicenter retrospective study, 363 patients with suspected bone and joint infections or osteomyelitis were included. Participants underwent 99mTc-MDP SPECT/CT and/or MRI examinations, supplemented by pathogenic bacterial cultures and histopathological analysis.

Results

Only SPECT/CT was tested in 169 patients, and only MRI was used in 116. 78 people have implemented both inspections and have detailed information. The diagnostic sensitivity and specificity of SPECT/CT for infection were 96% and 92% respectively, with an accuracy of 96%. For MRI, these figures were 88%, 84%, and 87% respectively.

Conclusion

This represents the largest global study to date evaluating osteomyelitis and bone infection diagnosis using 99mTc-MDP SPECT/CT tomographic fusion imaging. The findings indicate that 99mTc-MDP SPECT/CT fusion imaging offers superior diagnostic accuracy compared to MRI. This is particularly evident in cases involving metallic implants and chronic infections. 99mTc-MDP SPECT/CT fusion imaging emerges as a highly suitable non-invasive diagnostic modality, facilitating enhanced clinical follow-up and treatment.

Evaluating the efficacy of combined flap coverage, antibiotic-loaded bone cement and negative pressure irrigation in traumatic osteomyelitis management

Traumatic osteomyelitis with accompanying soft tissue defects presents a significant therapeutic challenge. This prospective, randomised controlled trial aims to evaluate the efficacy of antibiotic-impregnated bone cement, flap coverage and negative pressure sealed irrigation in the management of traumatic osteomyelitis complicated by soft tissue defects. A total of 46 patients with clinically diagnosed traumatic osteomyelitis and soft tissue defects were randomised into a control group (n = 23) and an observation group (n = 23). The control group underwent standard flap coverage and negative-pressure lavage, while the observation group received an additional treatment with antibiotic-loaded bone cement. Efficacy was measured based on clinical criteria, surgical metrics and morphometric assessment of bone and soft tissue defects. Statistical analyses were performed using SPSS version 27.0. The observation group, treated with an integrated approach of flap coverage, negative pressure wound therapy (NPWT) and antibiotic-impregnated bone cement, demonstrated significantly higher overall treatment efficacy (91.3%) compared to the control group, which received only flap coverage and NPWT (65.2%) (p < 0.01). This enhanced efficacy was evidenced through various outcomes: the observation group experienced reduced surgical times, shorter hospital stays, fewer dressing changes and accelerated wound healing, all statistically significant (p < 0.001). Additionally, a quantitative analysis at 6-month post-treatment revealed that the observation group showed more substantial reductions in both bone and soft tissue defect sizes compared to the control group (p < 0.001). The multi-modal treatment strategy, combining skin flap coverage, antibiotic bone cement and negative-pressure irrigation, showed marked efficacy in treating traumatic osteomyelitis and associated soft tissue defects. This approach accelerated postoperative recovery and lowered costs.

Choosing the right animal model for osteomyelitis research: Considerations and challenges

Osteomyelitis is a debilitating bone disorder characterized by an inflammatory process involving the bone marrow, bone cortex, periosteum, and surrounding soft tissue, which can ultimately result in bone destruction. The etiology of osteomyelitis can be infectious, caused by various microorganisms, or noninfectious, such as chronic nonbacterial osteomyelitis (CNO) and chronic recurrent multifocal osteomyelitis (CRMO). Researchers have turned to animal models to study the pathophysiology of osteomyelitis. However, selecting an appropriate animal model that accurately recapitulates the human pathology of osteomyelitis while controlling for multiple variables that influence different clinical presentations remains a significant challenge. In this review, we present an overview of various animal models used in osteomyelitis research, including rodent, rabbit, avian/chicken, porcine, minipig, canine, sheep, and goat models. We discuss the characteristics of each animal model and the corresponding clinical scenarios that can provide a basic rationale for experimental selection. This review highlights the importance of selecting an appropriate animal model for osteomyelitis research to improve the accuracy of the results and facilitate the development of novel treatment and management strategies.

Composition of pathogenic microorganism in chronic osteomyelitis based on metagenomic sequencing and its application value in etiological diagnosis

BACKGROUND

Traditionally, conventional microbiological culture methods have been used to detect pathogenic microorganisms in chronic osteomyelitis. However, these methods have been found to have a low detection rate, complicating the precise guidance of infection treatment. This study employed metagenomic next-generation sequencing (mNGS) to detect these microorganisms in chronic osteomyelitis with three main objectives: 1). Gain a deeper understanding of the composition of pathogenic microorganisms in chronic osteomyelitis. 2). Compare the microbial detection rates between mNGS and the standard culture methods used in laboratories to enhance the effectiveness of the traditional culture methods. 3). Explore the potential of mNGS in etiological diagnosis.

METHODS

Fifty clinically confirmed intraoperative bone tissue samples of chronic osteomyelitis from January 2021 to December 2021 were collected and subjected to mNGS and microbiological testing, respectively. The orthopaedic surgeon combined clinical manifestations and related examinations to determine the causative pathogens.

RESULTS

The culture method obtained 29 aerobic and parthenogenic anaerobic bacteria, 3 specific anaerobic bacteria, and 1 yeast-like fungus. Thirty-six aerobic and parthenogenic anaerobic bacteria, 11 specific anaerobic bacteria, and 1 yeast-like fungus were obtained by mNGS, and 2 Mycobacterium tuberculosis(MTB) strains were detected. However, there was no significant difference in the overall positive detection rate between mNGS and the culture method (P = 0.07), and the two were not statistically significant in detecting aerobic and partly anaerobic bacteria (P = 0.625). But, mNGS was significantly superior to culture in detecting anaerobic bacteria and Mycobacterium tuberculosis (P<0.05).

CONCLUSIONS

The mNGS method has enhanced our understanding of the distribution of pathogenic microorganisms in chronic osteomyelitis. Traditional culture methods help isolate and cultivate aerobic and facultative anaerobic bacteria, and fungi, and are also utilized for antibacterial drug sensitivity tests. However, mNGS has shown superior capabilities in detecting anaerobic bacteria, MTB, and mixed infection bacteria. This finding offers invaluable guidance for improving laboratory microbial culture and detection conditions. Hence, mNGS should be judiciously used for chronic osteomyelitis, and PCR can be implemented for certain difficult-to-culture microorganisms, such as MTB.

The effect of Staphylococcus aureus on innate and adaptive immunity and potential immunotherapy for S. aureus-induced osteomyelitis

Osteomyelitis is a chronic inflammatory bone disease caused by infection of open fractures or post-operative implants. Particularly in patients with open fractures, the risk of osteomyelitis is greatly increased as the soft tissue damage and bacterial infection are often more severe. Staphylococcus aureus, one of the most common pathogens of osteomyelitis, disrupts the immune response through multiple mechanisms, such as biofilm formation, virulence factor secretion, and metabolic pattern alteration, which attenuates the effectiveness of antibiotics and surgical debridement toward osteomyelitis. In osteomyelitis, immune cells such as neutrophils, macrophages and T cells are activated in response to pathogenic bacteria invasion with excessive inflammatory factor secretion, immune checkpoint overexpression, and downregulation of immune pathway transcription factors, which enhances osteoclastogenesis and results in bone destruction. Therefore, the study of the mechanisms of abnormal immunity will be a new breakthrough in the treatment of osteomyelitis.

Microbial Biofilm: A Review on Formation, Infection, Antibiotic Resistance, Control Measures, and Innovative Treatment

Biofilm is complex and consists of bacterial colonies that reside in an exopolysaccharide matrix that attaches to foreign surfaces in a living organism. Biofilm frequently leads to nosocomial, chronic infections in clinical settings. Since the bacteria in the biofilm have developed antibiotic resistance, using antibiotics alone to treat infections brought on by biofilm is ineffective. This review provides a succinct summary of the theories behind the composition of, formation of, and drug-resistant infections attributed to biofilm and cutting-edge curative approaches to counteract and treat biofilm. The high frequency of medical device-induced infections due to biofilm warrants the application of innovative technologies to manage the complexities presented by biofilm.

Comparison of internal and external fixation after debridement in the Masquelet technique for Cierny-Mader type IV tibial post-traumatic osteomyelitis

OBJECTIVE

To compare the effect of internal fixation vs. external fixation after debridement in stage I of the Masquelet technique for Cierny-Mader (C-M) type Ⅳ chronic post-traumatic tibial osteomyelitis.

METHODS

This retrospective observational study included patients with tibial osteomyelitis who underwent staged treatment with the Masquelet technique between January 2016 and June 2020 at the 920 Hospital of Joint Logistic Support Force of the PLA. The patients were grouped according to the fixation they received after stage I. Infection recurrence, time to radiological bone healing and full weight-bearing, self-rating anxiety scale (SAS) score, Hospital for Special Surgery (HSS) Knee Score, and American Orthopedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot Score were compared.

RESULTS

Sixty-three patients were included (50 males and 13 females). There were 40 and 23 patients with internal and external fixation, respectively. There were no significant differences between the two groups regarding the preoperative and intraoperative data (all P>0.05). After stage I operation, the infection control rates were 85.0% and 82.6% in the internal and external fixation groups (P=0.803), and these rates were 92.5% and 95.7% after stage II (P=0.621). There were no differences in the SAS scores (P=0.278), time to radiological union (P=0.795), time to full weight-bearing (P=0.725), AOFAS scores (P=0.302), HSS scores (P=0.085), and complication rates (P=0.593). There were 27 times complications in 19 patients, with an incidence of 42.9%, without significant differences between groups.

CONCLUSION

There were no differences between the two fixation methods after debridement in stage I of the Masquelet technique for C-M type Ⅳ chronic post-traumatic tibia osteomyelitis.

Micro-CT analysis of osteomyelitis of rabbit tibial for model establishment and biomaterials application in tissue engineering

Osteomyelitis is one of the most difficult diseases to treat in orthopedics field. The construction of animal models of osteomyelitis is now more mature but still lacks a deeper criterion other than "successful infection". In this work, rabbit tibial osteomyelitis model with S. aureus infection was established. Whole tibia, cortical bone around bone window, and tibial condyle were characterized in considerable detail using micro-CT and other means at 2/4/6 weeks, respectively. The results show that in addition to the obvious inflammatory response and bone destruction, osteomyelitis caused some other effects on compact and cancellous bone, and in particular, changes in bone mineral density after infection were of interest. Although the modeling groups all exhibited osteolysis and bone loss, their overall bone mineral density averages and those of the control groups were mostly in the range of 870 mg/cm3 to 920 mg/cm3, without statistical difference. The results suggest that overall bone mineral density is determined by both bone destruction conditions and the amount of dead bone deposition. This work provides a reference basis for the selection of time points for the subsequent animal models establishment and some valuable reference indicators of the application of biomaterials in tissue engineering.

Analysis of clinical characteristics, pathogen infection, and drug sensitivity of Marine injury patients: A cross-sectional study

The infection rate is high in patients injured at sea, and because of the unique distribution of marine microorganisms, the infection is often not easily controlled effectively with the empirical application of antibiotics. This study aims to consider the clinical characteristics and pathogen infection and drug susceptibility of patients injured at sea. From 2019 to 2021, there were 635 patients injured at sea in Rizhao People's Hospital. We assess the patient's basic condition, while performing bacterial culture and drug susceptibility testing on wound exudate or pus from infected patients. Among the 635 patients injured at sea, 195 people were infected, and the infection rate was 30.71%. Infected patients are usually older, have longer prehospital visits, and have lower normal levels of red blood cells, hemoglobin, total protein, and albumin. The causes of injury in infected patients were mainly avulsion and puncture injuries, and the types of injuries were mainly bone fracture, vascular injury, and nerve injury. A total of 305 strains of pathogenic bacteria were cultured in 195 patients. Gram-negative bacteria accounted for 77.05% (235 strains), of which Proteus was the most. Gram-positive bacteria accounted for 22.95% (70 strains), of which Staphylococcus aureus was the most. Gram-negative bacilli were sensitive to aminoglycosides, lactam antibiotics, carbapenems antibiotics, sulfonamides, quinolones, fourth-generation cephalosporins, and antibacterial drugs containing enzyme inhibitors, while most of the bacteria were resistant to penicillins, first-generation cephalosporins, and second-generation cephalosporins. Gram-positive bacteria were sensitive to quinuptin/dafoptin, rifampicin, linezolid, gentamicin, tigacycline, and vancomycin but resistant to penicillin antibiotics. Due to the particularity of marine injuries, patients are prone to infection. Pathogen culture and drug sensitivity analysis play an important role in guiding antiinfective treatment for marine injured patients.

Lipid liquid-crystalline nanoparticles sustained teicoplanin delivery for treatment of chronic osteomyelitis: In vitro and in vivo studies

AIM

The aim of our work is to formulate teicoplanin-loaded lipid liquid-crystalline (cubosomes) nanoparticles laden gel to sustain the release of teicoplanin for effective treatment of infected bone.

METHODS

Cubosomal gels were prepared by emulsification technique. The batches were characterized for morphology, size, entrapment efficacy, viscosity, in-vitro flux, in-vivo drug release and histopathological studies.

RESULTS

Transmission electron microscopy images confirmed the bi-continuous liquid crystalline phase. The size (61-202nm), viscosity (12,138-13,132cp), and entrapment efficacy (69.0-81.8% w/w) increase with the level of glycerol monooleate. The in-vitro flux data showed sustain teicoplanin release from the cubosomal gels for 36 days, compared to 48h from the control gel. The in-vivo teicoplanin release study (osteomyelitis induced by S. aureus) showed low serum drug-concentration from the gel (up to 14 days) compared to high-serum drug-concentration using intravenous injections.

CONCUSSION

In conclusion the study demonstrated the potential of cubosomes for effective delivery of teicoplanin to replace injections.

Relieving the Incompatibility of Network Representation and Classification for Long-Tailed Data Distribution

In the real-world scenario, data often have a long-tailed distribution and training deep neural networks on such an imbalanced dataset has become a great challenge. The main problem caused by a long-tailed data distribution is that common classes will dominate the training results and achieve a very low accuracy on the rare classes. Recent work focuses on improving the network representation ability to overcome the long-tailed problem, while it always ignores adapting the network classifier to a long-tailed case, which will cause the "incompatibility" problem of network representation and network classifier. In this paper, we use knowledge distillation to solve the long-tailed data distribution problem and fully optimize the network representation and classifier simultaneously. We propose multiexperts knowledge distillation with class-balanced sampling to jointly learn high-quality network representation and classifier. Also, a channel activation-based knowledge distillation method is also proposed to improve the performance further. State-of-the-art performance on several large-scale long-tailed classification datasets shows the superior generalization of our method.

Expert Consensus on the Contraindications and Cautions of Foam Rolling-An International Delphi Study

Background: Foam rolling is a type of self-massage using tools such as foam or roller sticks. However, to date, there is no consensus on contraindications and cautions of foam rolling. A methodological approach to narrow that research gap is to obtain reliable opinions of expert groups. The aim of the study was to develop experts’ consensus on contraindications and cautions of foam rolling by means of a Delphi process. Methods: An international three-round Delphi study was conducted. Academic experts, defined as having (co-) authored at least one PubMed-listed paper on foam rolling, were invited to participate. Rounds 1 and 2 involved generation and rating of a list of possible contraindications and cautions of foam rolling. In round 3, participants indicated their agreement on contraindications and cautions for a final set of conditions. Consensus was evaluated using a priori defined criteria. Consensus on contraindications and cautions was considered as reached if more than 70% of participating experts labeled the respective item as contraindication and contraindication or caution, respectively, in round 3. Results: In the final Delphi process round, responses were received from 37 participants. Panel participants were predominantly sports scientists (n = 21), physiotherapists (n = 6), and medical professionals (n = 5). Consensus on contraindications was reached for open wounds (73% agreement) and bone fractures (84%). Consensus on cautions was achieved for local tissue inflammation (97%), deep vein thrombosis (97%), osteomyelitis (94%), and myositis ossificans (92%). The highest impact/severity of an adverse event caused by contraindication/cautions was estimated for bone fractures, deep vein thrombosis, and osteomyelitis. Discussion: The mechanical forces applied through foam rolling can be considered as potential threats leading to adverse events in the context of the identified contraindications and cautions. Further evaluations by medical professionals as well as the collection of clinical data are needed to assess the risks of foam rolling and to generate guidance for different applications and professional backgrounds.