Role of MRI in the diagnosis and treatment of osteomyelitis in pediatric patients

Logistic regression analysis of multiple rapid admission hematological indicators to determine the risk of osteomyelitis in infected children

To analyze the differences of multiple rapid admission hematological indicators between children with acute osteomyelitis (AO) and children with other orthopedic infectious diseases and clarify the characteristics of admission inspection hematological indicators of children with AO. Retrospective analysis of this pilot study was proceeded on 144 children with limbs infectious diseases, who were treated in our hospital. According to their final diagnosis, they were divided into osteomyelitis group (n = 57) and non-osteomyelitis group (n = 87). Case data were collected, including sex, age, body temperature, white blood cell (WBC), C-reactive protein (CRP), etc. The differences in these indexes between the two groups of patients were compared, and then, the index with significant differences was selected for univariate and multivariate logistic regression analysis. There were significant differences between the two groups in age, body temperature, CRP, ESR, fibrinogen, total bilirubin, alanine aminotransferase, aspartate aminotransferase (AST), glutamyl transpeptidase, creatinine, PCT, albumin (ALB), and ALB globulin ratio (A/G) ( P  < 0.05). The results of univariate and multivariate logistic regression analysis showed that the age of ≥5 years (4.592, 1.711-12.324), WBC (>1.5 × 10 9 /L) (0.271, 0.102-0.718), ESR (>50 mm/h) (6.410, 2.291-17.936), PCT (>0.06 µg/L) (3.139, 1.066-9.243), and AST (>40 U/L) (11.174, 1.718-72.666) was an independent risk factor of AO in children with orthopedic infectious diseases ( P  < 0.05). For newly admitted children with orthopedic infectious diseases, if the age ≥ 5 years, WBC ≤ 1.5 × 10 9 /L, ESR > 50 mm/h, PCT > 0.06 µg/L, and AST > 40 U/L, the occurrence of AO should be alerted.

[18F]Fluorodeoxyglucose ([18F]FDG) positron emission tomography and conventional imaging modalities in the diagnosis of diabetic foot osteomyelitis: a meta-analysis

AIM

This meta-analysis aimed to evaluate the comparative diagnostic efficacy of [18F]Fluorodeoxyglucose positron emission tomography ([18F]FDG PET) and conventional imaging, MRI, and white blood cell (WBC) scintigraphy in detecting foot osteomyelitis among diabetic patients.

MATERIALS AND METHODS

An exhaustive search was conducted within the PubMed and Embase databases to identify publications available up until February 2024. Studies were included if they evaluated the diagnostic efficacy of [18F]FDG PET or the comparative diagnostic performance between PET and (MRI or WBC scintigraphy). Two researchers independently assessed the quality of the included studies, utilizing the Quality Assessment of Diagnostic Performance Studies (QUADAS-2) tool.

RESULTS

Nine retrospective or prospective studies involving 605 patients were included in the meta-analysis. For [18F]FDG PET, the overall sensitivity was 0.83(95% CI: 0.69-0.94), while the overall specificity was 0.92(95% CI: 0.86-0.97). In the head-to-head comparison, no significant difference of sensitivity was found between [18F]FDG PET and MRI (0.72 vs. 0.68, P=0.81), as well as between [18F]FDG PET and WBC scintigraphy (0.57 vs. 0.66, P=0.64). In addition, specificity was also found to be no significant difference between [18F]FDG PET and MRI (0.90 vs. 0.82, P=0.27), as well as [18F]FDG PET and WBC scintigraphy (0.81 vs. 0.93, P=0.09).

CONCLUSION

[18F]FDG PET demonstrates similar sensitivity and specificity to MRI and WBC scintigraphy in detecting foot osteomyelitis among diabetic patients. MRI, often cited as a primary choice in guidelines, might be preferred due to its lower cost and lower dose. Further larger sample prospective studies are needed to confirm these findings.

The many faces of sickle cell disease in children: complications in the appendicular skeleton

Sickle cell disease (SCD) is a hereditary red cell disorder with clinical manifestations secondary to sickling or crescent-shaped distortion of the red blood cells. Musculoskeletal complications of SCD are often the main causes for acute and chronic morbidities in children with manifestations including osteomyelitis, osteoporosis and osteonecrosis. This article aims to familiarise the paediatric radiologist with appendicular skeletal complications of SCD in the paediatric population and their imaging appearance.

Diagnostic performance comparison of conventional radiography to magnetic resonance imaging for suspected osteomyelitis of the extremities: a multi-reader study

OBJECTIVE

To determine whether MRI provides improved diagnostic accuracy compared to radiography for the diagnosis of extremity osteomyelitis (OM) with multi-reader analysis.

METHODS

In this cross-sectional study, three musculoskeletal fellowship-trained expert radiologists evaluated cases of suspected OM in two rounds-first using radiographs (XR), then with conventional MRI. Radiologic features consistent with OM were recorded. Each reader recorded individual findings on both modalities and rendered a binary diagnosis along with certainty of final diagnosis on a confidence scale of 1-5. This was compared with the pathology-proven diagnosis of OM to determine diagnostic performance. Intraclass correlation (ICC) and Conger's Kappa were used for statistics.

RESULTS

XR and MRIs of 213 pathology proven cases (51.5 years ± 14.0 years, mean ± St.Dev.) were included in this study, with 79 tested positive for OM and 98 were positive for a soft tissue abscess, with 78 patients being negative for both. In total, 139 were males and 74 females with bones of interest in the upper and lower extremities in 29 and 184 cases, respectively. MRI showed significantly higher sensitivity and negative predictive value than XR (p < 0.001 for both metrics). Conger's Kappa for OM diagnosis were 0.62 and 0.74 on XR and MRI, respectively. Reader confidence improved slightly from 4.54 to 4.57 when MRI was used.

CONCLUSIONS

MRI is a diagnostically more effective imaging modality than XR for finding extremity osteomyelitis with better inter-reader reliability.

CLINICAL RELEVANCE STATEMENT

This study validates the diagnosis of OM with MRI over XR but adds novelty because it is the largest study of its kind with a clear reference standard to guide clinician decision making.

KEY POINTS

• Radiography is the first-line imaging modality for musculoskeletal pathology but MRI can add value for infections. • MRI shows greater sensitivity for the diagnosis of osteomyelitis of the extremities than radiography. • This improved diagnostic accuracy makes MRI a better imaging modality for patients with suspected osteomyelitis.

An Abbreviated Non-Contrast MRI Protocol for Osteomyelitis May Reduce the Need for Sedation in Young Children

Lengthy MRI examinations in young children often requires sedation. When sedation is unavailable, critical imaging may be delayed. Abbreviating the imaging protocol to a few essential sequences may reduce the need for sedation and prevent delays in patient care. We retrospectively evaluated an abbreviated noncontrast MRI protocol to diagnose lower extremity osteomyelitis in the pediatric population. The IRB approved this study. The radiology information system was searched for lower extremity MRI examinations for osteomyelitis in patients <20 years old from August 2020 to August 2021. Three noncontrast sequences (long axis T1 without fat saturation (FS), long axis STIR, and axial T2 with FS) were independently reviewed by 2 pediatric radiologists. The accuracy of the reviewers was compared to the clinical radiology report based on the unabridged contrast-enhanced standard department protocol. The search yielded 80 exams, mean age was 7 years old, 59% (47/80) were male, and 41% (33/80) were female. The accuracies of reviewer A and reviewer B were 95% and 89%, respectively. The reviewer inter-observer agreement for the diagnosis of osteomyelitis was strong (k = 0.79). The accuracy of an abbreviated noncontrast MRI protocol to evaluate lower extremity osteomyelitis in children approaches that of the unabridged protocol and has the potential to decrease the need for sedation in young children.

Predictive Value of Radiographic and Magnetic Resonance Imaging Characteristics on Patient Outcomes in Confirmed Acute Osteomyelitis of the Extremities

OBJECTIVE

The aim of this study was to determine whether imaging characteristics on plain radiography, magnetic resonance imaging (MRI), and diffusion-weighted imaging are predictive of patient outcomes in cases of confirmed osteomyelitis (OM).

MATERIALS AND METHODS

In this cross-sectional study, 3 experienced musculoskeletal radiologists evaluated pathologically proven cases of acute extremity OM and recorded imaging characteristics on plain radiographs, MRI, and diffusion-weighted imaging. These characteristics were then compared with the patient outcomes after a 3-year follow-up using length of stay, amputation-free survival, readmission-free survival, and overall survival using multivariate Cox regression analysis. Hazard ratio and corresponding 95% confidence intervals are reported. False discovery rate-adjusted P values were reported.

RESULTS

For the 75 consecutive cases of OM in this study, multivariate Cox regression analysis adjusting for sex, race, age, body mass index, erythrocyte sedimentation rate, C-reactive protein, and white blood cell count showed no correlation among any of the recorded characteristics on imaging and patient outcomes. Despite the high sensitivity and specificity of MRI for diagnosing OM, there was no correlation between MRI characteristics and patient outcomes. Furthermore, patients with coexistent abscess of the soft tissue or bone with OM had comparable outcomes using the previously mentioned metrics of length of stay, amputation-free survival, readmission-free survival, and overall survival.

CONCLUSION

Neither radiography nor MRI features predict patient outcomes in extremity OM.

Incremental value of diffusion weighted imaging over conventional MRI for the diagnosis of osteomyelitis of extremities

OBJECTIVE

To determine the incremental value of diffusion weighted imaging (DWI) over conventional MR imaging in diagnosing extremity osteomyelitis (OM).

MATERIALS AND METHODS

In this cross-sectional study, three experienced musculoskeletal radiologists evaluated clinically suspected cases of extremity OM in two rounds-first on conventional MR imaging, and then conventional MR imaging combined with DWI 4-6 weeks later. The readers recorded a result of the presence or absence of OM and their diagnostic confidence on a 1-5 scale. Mean and minimum apparent diffusion coefficient (ADC) were measured. Pathology diagnosis served as the reference standard. Statistical analysis utilized intraclass correlation (ICC) and Conger's kappa.

RESULTS

A total of 213 scans of suspected OM were reviewed by three musculoskeletal radiologists with no significant changes in sensitivity (0.97, 0.97), specificity (0.97, 0.94), positive predictive value (0.91, 0.87), or negative predictive value (0.98, 0.98) between conventional MR imaging and MR imaging combined with DWI, respectively. Reader confidence did not significantly change with the addition of DWI (4.55 and 4.70, respectively). A high inter-reader agreement was observed for the diagnosis of OM, soft tissue abscess, and intraosseous abscess in both rounds. A higher mean (1.46+/-0.43 × 10-3 mm2/s > 0.64+/-0.47 × 10-3mm2/s) and minimum (1.18+/-0.45 × 10-3mm2/s > 0.37+/-0.44 × 10-3mm2/s) ADC value was associated with OM (p-value < 0.0001) with odds ratios of 1.34 and 1.31, respectively, for mean and minimum ADC of the involved bone.

CONCLUSION

DWI-derived ADC increase is associated with OM. The use of DWI slightly increases reader confidence in the diagnosis of OM; however, no significant incremental value over conventional MR imaging is seen for the final diagnosis of OM.

Acute Osteomyelitis of the Pubic Symphysis: A Case Report

Pubis osteomyelitis is an uncommon disease, accounting for less than 1% of all bone infections. It occurs secondarily to hematogenous bacterial planting or direct inoculation. Clinically, it presents with intense acute pubic pain, limited mobility, and high fever, so it is rarely suspected initially. Its diagnosis can be easily confused with pubalgia, that do not respond to treatment. We present the case of a 17-year-old patient who sought consultation for three weeks of coxalgia associated with general discomfort and fever. Following a laboratory and imageological study, the diagnosis of acute pubis osteomyelitis was determined, which required surgical intervention and a subsequent pharmacological therapy for six weeks.

Pediatric musculoskeletal infections

PURPOSE OF REVIEW

The aim of this article is to review the recent guidelines and literature regarding the diagnosis and the treatment of common pediatric musculoskeletal infections: septic arthritis, osteomyelitis, pyomyositis, and Lyme disease.

RECENT FINDINGS

In the last decade, a better understanding of the causative organisms of common bacterial infections, including Kingella , leads to prompt targeted antimicrobial coverage in all musculoskeletal infections. Prompt diagnosis and treatment continues to be the mainstay in the treatment of children with osteoarticular infections. Efforts to improve early detection have lead to improving rapid lab diagnostic testing; however, more advanced diagnostics such as arthrocentesis for septic arthritis and MRI for osteomyelitis and pyomyositis, remain the gold standard. Shorter and narrowed antibiotic courses, with appropriate transition to outpatient oral treatment provide effective infection clearance and reduction in complications of disease.

SUMMARY

Advances in diagnostics, including pathogen identification as well as imaging continues to improve our ability to diagnose and treat these infections, although still lack ability to provide definitive diagnosis without more invasive nor advanced techniques.

Clinical outcomes of pediatric osteomyelitis

BACKGROUND

Osteomyelitis in children may produce severe sequelae. However, the frequency and distribution of such complications by type of osteomyelitis (chronic or acute) is not well described.

METHODS

We searched the HealthFacts® database (containing medical information on 68 million individual patients in the United States) with 238 International Classification of Diseases (ICD) version 10 codes for acute osteomyelitis and chronic osteomyelitis appearing in 2015. Outcomes were recorded for each subject, including development of limb length discrepancies, pathologic fractures, mortality, and need for multiple surgeries or prolonged orthopedic care (one to two years following diagnosis). Gender, age and season of diagnosis were also assessed. Chi-square tests were used to compare differences between categorical variables, and t-tests between continuous variables.

RESULTS

Eight hundred sixty-nine subjects were included (57.4% male). Children with chronic osteomyelitis were older than those with acute osteomyelitis (median 9.5 years vs 12.0, respectively, p = .0004). Diagnoses were more common in winter (p = .0003). Four subjects died while hospitalized during the study period (two with acute osteomyelitis, two with chronic osteomyelitis). Limb length discrepancies were rare and similarly distributed between infection types (≤ 1.3% of subjects, p = .83). Subjects with chronic osteomyeltis were more likely to require long-term orthopedic follow-up (14.0% vs. 4.8% for acute osteomyelitis, p < .0001), suffer from pathologic fractures (1.5% vs < 1.0%, p = .003) and to require multiple surgeries (46.0% vs. 29.3%, p = .04).

CONCLUSIONS

Though infrequent, serious outcomes from osteomyelitis are more common with chronic osteomyelitis than acute osteomyelitis.

Fever and Knee Effusion in the Pediatric Patient

ABSTRACT

The pediatric patient with fever and knee effusion is always a cause for clinical concern. A thorough history and physical examination is required to guide appropriate diagnostic evaluation and management. Although pediatric knee effusions are common in the setting of trauma, the presence of fever should prompt consideration of infectious, rheumatologic, vasculitic, and malignant etiologies. This review covers the key components of the history, physical examination, diagnostic strategies, common etiologies, and initial management of the pediatric patient with fever and knee effusion.

Ankle sprain injury in child and adolescent: Diagnostic pitfalls

Introduction and importance

Sprained ankles in children and adolescents are rare. Certain diagnostic pitfalls must arise in the mind of the clinician because many differential diagnoses must be confirmed or refuted urgently. Among them, the infectious osteoarticular pathology including acute hematogenous osteomyelitis of the tibia or distal fibula and septic arthritis of the subtalar joint.

The main purpose of this work, through four clinical cases, we will discuss diagnostic pitfalls in the course of ankle trauma in children and adolescents.

Case presentation clinical

In this work, we have demonstrated through four cases some diagnostic errors in the context of ankle trauma in children and adolescents. Infectious and malignant tumor pathologies are real diagnostic and therapeutic emergencies. For all these cases, the initial diagnosis was a sprained ankle following a gambling or sports accident.

Discussion

Ankle trauma in children and adolescents is a frequent reason for consultation in emergencies. The fear of the orthopedic surgeon is to miss a serious pathology and wrongly make the simple diagnosis of a sprained ankle. Temperature measurement must be systematic. The clinical examination must be meticulous. The interpretation of the radiograph must be cautious. Acute hematogenous osteomyelitis and malignant tumor pathology should be on the surgeon's mind.

Conclusion

We have shown through these four examples that a serious pathology can simulate a sprain. Hence, a careful analysis of clinical, biological and radiological elements is the only guarantee of adequate care.

•

Ankle trauma in children is a frequent reason for consultation in trauma emergencies.

•

Real lesions of the lateral ankle ligament in children are rare.

•

The measurement of the temperature in a child who consults in traumatology should be systematic.

•

Interpretation of radiographs should be careful.

Pediatric Emergency MRI

There is an overall increase in the use of imaging in the pediatric emergency room setting, which is accompanied by a reduction in computed tomography examinations performed mainly due to the increased awareness of the risks of ionizing radiation. Advances in MRI technology have led to shortened scan time, decreased motion sensitivity, and improved spatial resolution. With increased access to MRI in the emergency room setting, the goal of this article is to review major applications of MR in pediatric emergency room patients.

Systematic review: investigating the added diagnostic value of gadolinium contrast agents for osteomyelitis in the appendicular skeleton

OBJECTIVE

Osteomyelitis is an infection of the bone marrow. MRI with gadolinium-based contrast is frequently performed for cases of suspected osteomyelitis. The objective of this systematic review is to examine the diagnostic accuracy of contrast-enhanced vs non-contrast-enhanced MRI for osteomyelitis in the appendicular skeleton.

MATERIALS AND METHODS

We conducted a systematic review of MRI in the diagnosis of osteomyelitis by searching MEDLINE and EMBASE from January 2000 to March 2020. There were 21 studies that met the inclusion criteria for the systematic review for a total of 1095 patients. Analytic methods were based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses. Evidence was evaluated using the STARD criteria for evaluation of completeness and transparency of reporting.

RESULTS

For diagnosing osteomyelitis in the appendicular skeleton, MRI with gadolinium-based contrast has 89% sensitivity (95% CI, 86-92%), 79% specificity (95% CI, 75-83%), and 90% overall diagnostic accuracy ([SE] = 0.03). For diagnosing osteomyelitis in the appendicular skeleton, MRI without gadolinium-based contrast has a 92% sensitivity (95% CI, 87-96%), 89% specificity (95% CI, 84-93%), and 96% overall diagnostic accuracy ([SE] = 0.03). The median score of included studies was 85% utilizing the STARD criteria with excellent interobserver agreement of 83.4%. Limitations included small sample size of studies, with retrospective designs.

CONCLUSION

No evidence was found to suggest an added diagnostic value of gadolinium contrast for the diagnosis of osteomyelitis in the appendicular skeleton. For routine cases of suspected non-spinal osteomyelitis, non-contrast MRI of the area of interest is the next most appropriate study after radiographs.

Practice Variation in the Surgical Management of Children With Acute Hematogenous Osteomyelitis

INTRODUCTION

The surgical indications to manage children with acute hematogenous osteomyelitis (AHO) remain poorly defined. The purpose of this study was to identify if practice pattern variation exists in the surgical management of pediatric AHO among tertiary pediatric medical centers across the United States. A secondary purpose was to evaluate variables that may impact the rate of surgical intervention among these institutions.

METHODS

Children with AHO were retrospectively analyzed between January 1, 2010, and December 31, 2016, from 18 pediatric medical centers throughout the United States. The rates of surgery were identified. Admission vitals, labs, weight-bearing status, length of stay, and readmission rates were compared between those who did and did not undergo surgery. Multivariate regression and classification and regression tree analyses were performed to identify the variables that were associated with surgical intervention.

RESULTS

Of the 1003 children identified with AHO in this retrospective, multicenter database, 619/1003 (62%) were treated surgically. Multivariate analysis revealed institution, inability to ambulate, presence of multifocal infection, elevated admission C-reactive protein, increased admission platelet count, and location of the osteomyelitis were significant predictors of surgery (P<0.01). Patients who underwent surgery were more than twice as likely to have a recurrence or readmission and stayed a median of 2 days longer than those who did not have surgery. In the classification and regression tree analysis, 2 distinct patterns of surgical intervention were identified based on institution, with 12 institutions operating in most cases (72%), regardless of clinical factors. A second cohort of 6 institutions operated less routinely, with 47% receiving surgery overall. At these 6 institutions, patients without multifocal infection only received surgery 26% of the time, which increased to 74% with multifocal infection and admission erythrocyte sedimentation rate >37.5 mm/h.

CONCLUSIONS

This study is the first to objectively identify significant differences in the rates of surgical management of pediatric AHO across the United States. Variation in the surgical management of AHO appears to be driven primarily based on institutional practice. Twelve institutions operated on 72% of patients, regardless of the severity of disease, indicating that the institution custom or dogma may drive the surgical indications. Six institutions relied more on clinical judgment with significant variability in rates of surgical intervention (26% vs. 74%), depending on the severity of the disease. Surgical intervention is associated with increased recurrence, readmission, and hospital length of stay. As a result of these findings, it is essential to prospectively study the appropriate surgical indications and measure the outcomes in children with pediatric AHO.

LEVEL OF EVIDENCE

Level III.

Treatment of long bone infection by a biodegradable bone cement releasing antibiotics in human

Repair of methicillin-resistant Staphylococcal (MRSA) chronic osteomyelitis and resulting bone defect is one of the major challenges in orthopaedics. Previous study has shown the effectiveness of antibiotic loaded biodegradable composite bone cement with in vitro tests and in the treatment of experimental osteomyelitis. The cement is composed of poly(lactide-co-glycolide) encapsulated antibiotic-biphasic calcium phosphate granule complex and additive antibiotic powder in gypsum binder. In this study, the cement was studied further to evaluate its in vitro biological properties (cytocompatibility, platelet activation), anti-infective, and bone regenerative potential in comparison to poly(methyl methacrylate) (PMMA) cement and parenteral therapy in 43 patients (age 5-57 years) with chronic MRSA osteomyelitis by analyzing the results of histopathology, radiographs, magnetic resonance imaging, scanning electron microscopy, and serum drug concentrations for 1 year. The composite cement showed superior cytocompatibility and coagulant activity compared to PMMA cement. Moreover, the results of different postoperative clinical and radiological examinations also proved the supremacy of composite cement over the other treatment modalities in terms of success rate, faster sepsis control and bone regeneration. Low serum antibiotic concentrations and normal serum calcium levels indicate that the calcium-rich composite cement is safe for application in human. Therefore, we conclude that the composite bone cement is a promising candidate for the treatment of chronic osteomyelitis.

Chronic Osteomyelitis of Long Bones: Imaging Pearls and Pitfalls in Pediatrics

Chronic bacterial osteomyelitis is characterized by progressive inflammatory bone destruction and apposition of new bone most often caused by pyogenic bacteria. Clinical findings are nonspecific, and serum inflammatory markers can be normal. Prompt diagnosis and treatment are essential. Left untreated, chronic infection can lead to high morbidity and mortality. Imaging's major role is to suggest the correct diagnosis, exclude other diagnoses that can mimic osteomyelitis, document extent of disease, and guide interventions such as image-guided biopsy or surgical debridement. Several conditions can mimic chronic osteomyelitis clinically and radiographically. The main differential diagnoses include an oncologic process, chronic nonbacterial or chronic recurrent multifocal osteomyelitis, bone infarct in sickle cell disease, osteoid osteoma, and stress reaction/fracture. The oncologic process to consider includes metastatic neuroblastoma and Langerhans cell histiocytosis in a child younger than five years or leukemia, Ewing sarcoma, and osteosarcoma in the older age group. However, these lesions can typically be excluded based on radiographs and magnetic resonance imaging findings. Therefore, radiologist familiarity with imaging findings and mimickers is essential. In this article, we briefly review the epidemiologic, clinical, and histopathologic features of chronic bacterial osteomyelitis and emphasize imaging pearls and pitfalls, with discussion of the most common differential diagnoses.

Clinical Presentation of Acute Osteomyelitis in the Pediatric Emergency Department

OBJECTIVES

Acute osteomyelitis is a challenging diagnosis to make in the pediatric emergency department (ED), in part because of variability in its presentation. There are limited data detailing the presenting features of pediatric osteomyelitis, factors that are essential to understand to inform diagnostic decision making. We sought to describe relevant clinical data that contributed to the diagnosis of acute osteomyelitis in children presenting to a pediatric ED.

METHODS

This was a 10-year retrospective cohort study of patients 18 years or younger diagnosed with acute osteomyelitis in the ED of a large tertiary care children's hospital. Collected data included demographics, clinical history, patient-reported symptoms, vital signs, physical examination findings, and results of basic laboratory, microbiologic, and imaging studies. Descriptive statistics were used to summarize key findings.

RESULTS

Two hundred eleven cases of acute osteomyelitis were identified during the study period. The median age was 8.4 years, with 61.1% male. One hundred twenty-seven patients (60.2%) presented to care more than once before being diagnosed. Common symptoms included pain (94.3%), functional limitation (83.9%), and fever (76.3%). Common examination findings included functional limitation (78.2%), focal tenderness (73.5%), and swelling (52.1%). One hundred seventeen patients (55.5%) were febrile during their ED evaluation. Elevated C-reactive protein (>0.8 mg/dL, 92.9%) and erythrocyte sedimentation rate (>10 mm/h, 94.3%) were the most sensitive laboratory markers.

CONCLUSIONS

Fever may be absent in up to a quarter of pediatric patients with acute osteomyelitis. Although highly sensitive, inflammatory marker elevations were more modest than those reported previously in cases of pediatric septic arthritis.

Osteomyelitis in Immunocompromised children and neonates, a case series

BACKGROUND

Osteomyelitis in immunocompromised children can present differently from immunocompetent children and can cause devastating sequelae if treated inadequately. We aim to review the aetiology, clinical profile, treatment and outcomes of immunocompromised children with osteomyelitis.

METHODS

Retrospective review of all immunocompromised children aged < 16 years and neonates admitted with osteomyelitis in our hospital between January 2000 and January 2017, and referred to the Paediatric Infectious Disease Service.

RESULTS

Fourteen patients were identified. There were 10 boys (71%), and the median age at admission was 70.5 months (inter-quartile range: 12.3-135.0 months). Causal organisms included, two were Staphylococcus aureus, two were Mycobacterium bovis (BCG), and one each was Mycobacterium tuberculosis, Pseudomonas aeruginosa, Stenotrophomonas maltophilia, Burkholderia pseudomallei and Rhizopus sp. One patient had both Clostridium tertium and Clostridium difficile isolated. Treatment involved appropriate antimicrobials for a duration ranging from 6 weeks to 1 year, and surgery in 11 patients (79%). Wherever possible, the patients received treatment for their underlying immunodeficiency. For outcomes, only three patients (21%) recovered completely. Five patients (36%) had poor bone growth, one patient had recurrent discharge from the bone and one patient had palliative care for underlying osteosarcoma.

CONCLUSIONS

Although uncommon, osteomyelitis in immunocompromised children and neonates can be caused by unusual pathogens, and can occur with devastating effects. Treatment involves prolonged administration of antibiotics and surgery. Immune recovery also seems to be an important factor in bone healing.

Predicting adjacent infections in pediatric septic arthritis: Do predictive criteria extrapolate across geographic regions?: Predicting Periarticular Infection in the Southeast

Purpose

This study aims to assess previously determined predictive criteria for presence of adjacent infection in septic arthritis within a Southeastern United States (US) pediatric population.

Results

The sensitivity, specificity, positive predictive value, and negative predictive value of the Rosenfeld criteria were: 91.7%, 22.7%, 39.3%, and 83.3%, respectively. The patients with periarticular infection were more likely to have positive blood cultures than those with isolated septic arthritis. There was no difference in likelihood of secondary surgical intervention.

Conclusions

Previously defined criteria to predict adjacent infection in pediatric septic arthritis did not demonstrate external validity in a Southeastern US pediatric population.

Delayed Presentation of Seymour Fractures: A Single Institution Experience and Management Recommendations

Background: Seymour fractures in children are prone to complications without prompt and appropriate treatment. This study investigated outcomes of Seymour fractures with delayed presentations; specifically, if deep infection predisposed to operative treatment, if antibiotic administration improved fracture healing, and if oral clindamycin had fewer treatment failures than oral cephalexin. Methods: A single-institution retrospective cohort study was performed of patients with delayed Seymour fracture presentations (defined as greater than 24 hours post-injury) between 2009 and 2017. Data collected included demographics, time to presentation, infection on presentation, operative treatment, antibiotic use and duration, fracture union, and complications. Statistical testing used logistic regression and Fisher's exact test, with results reported as P-values (P), odds ratios (ORs), and 95% confidence intervals (CIs). Results: There were 73 patients with delayed Seymour fracture presentations, with mean age of 11.1 years (standard deviation: 2.9), with 56 (77%) males, and median time to presentation of 7 days (interquartile range: 3-17). Deep infection on presentation was a risk factor for operative intervention (OR = 34.4, P = .0001, CI, 5.5-217.2). Antibiotic administration protected against the development of a nonunion or delayed union (OR = 0.11, P = .008, CI, 0.021-0.57). Time to antibiotics did not protect against nonunion or delayed union (OR = 0.77, P = .306, CI, 0.37-1.3). Clindamycin had fewer treatment failures than cephalexin (P = .039). Conclusions: Deep infection is a risk factor for operative treatment of Seymour fractures with delayed presentations. Clindamycin is a better antibiotic choice for Seymour fractures that present in delayed fashion.

The erroneous perception of a clinical sign: Cholestasis preceding sepsis mimicking hepatitis in an adolescent patient

Jaundice should be considered as a first clinical sign preceding severe invasive bacterial infection or sepsis in patients of all ages including childhood and adolescence. Early laboratory investigations and MR imaging studies for osteomyelitis or myositis are paramount to avoid progression to life-threatening sepsis and significant morbidity and mortality.

Updates and Advances: Pediatric Musculoskeletal Infection Imaging Made Easier for Radiologists and Clinicians

Infants and children often present with a wide range of musculoskeletal (MSK) infections in daily clinical practice. This can vary from relatively benign superficial infections such as cellulitis to destructive osseous and articular infections and life-threatening deep soft tissue processes such as necrotizing fasciitis. Imaging evaluation plays an essential role for initial detection and follow-up evaluation of pediatric MSK infections. Therefore, a clear and up-to-date knowledge of imaging manifestations in MSK infections in infants and children is imperative for timely and accurate diagnosis that, in turn, can result in optimal patient management. This article reviews an up-to-date practical imaging techniques, the differences between pediatric and adult MSK infections, the spectrum of pediatric MSK infections, and mimics of pediatric MSK infections encountered in daily clinical practice by radiologists and clinicians.

Radiological evaluation of postoperative osteomyelitis in long bones: Which is the best tool?

Currently, definitive diagnosis of osteomyelitis involves a combination of clinical signs, symptoms, laboratory tests, imaging modalities and cultures from blood, joint or body fluid. Imaging plays a critical role in the osteomyelitis diagnosis. Each of these tests incurs an additional cost to the patient or healthcare system and their use varies according to the preference of the healthcare professional and the healthcare setup. Imaging plays a critical role in the diagnosis and management of postoperative long bone osteomyelitis, with the aim of reducing long-term complications such as non-union, amputation and pathological fractures. In this review, we discuss the key findings on different radiological modalities and correlate them with disease pathophysiology. Currently, magnetic resonance imaging is the best available imaging modality due to its sensitivity in detecting early signs of long bone osteomyelitis and high soft tissue resolution. Other modalities such as radio-nuclear medicine, computed tomography and ultrasound have been proved to be useful in different clinical scenarios as described in this narrative review.

Contiguous Osteomyelitis of Distal Extremities in Children

Objective. To evaluate the burden of Contiguous Osteomyelitis (COM) in pediatric patients with cellulitis/abscess of hands/feet. Methods. Children aged 0-18 years, treated from 2009 to 2019 for cellulitis/abscess of hands/feet, who either had Magnetic Resonance Imaging at presentation, or Roentgenogram >10 days after symptom-onset, were included. Two-tailed T-test was used to compare patients with and without COM. P-value < .05 deemed statistically significant. Results. Twenty of forty-one patients with abscess/cellulitis of distal extremities were diagnosed with COM. Between groups, no differences identified in trauma-to-presentation time, antibiotic treatment for >48 hours before admission, abscess versus cellulitis, location of infection, presence of fever, or signs of infection. Conclusion. In our cohort, clinical presentation did not differentiate COM. Imaging helped diagnose patients with COM, who would otherwise receive a shorter antibiotic course. Hands/feet imaging in pediatric patients hospitalized with cellulitis/abscess should be considered to identify COM and customize treatment. Further research is warranted.

Difficulties in diagnosing vertebral osteomyelitis in a child

Vertebral osteomyelitis is a rare diagnosis and often delayed diagnosis in children. This is a case of a child presenting with fever, back pain and raised C reactive protein who was found to have a Staphylococcus aureus (S.aureus) bacteraemia. Initial imaging with CT, MRI of the spine and abdominal ultrasound failed to demonstrate a vertebral osteomyelitis or identify another source of the bacteraemia. Due to the high clinical suspicion of a spinal source of the infection, second-line investigations were arranged. A bone scan identified an area of increase metabolic activity in the 12th thoracic vertebrae (T12) and subsequently a diagnosis was confirmed with a focused MRI of T12. This serves as an opportunity to discuss the diagnostic difficulty presented by paediatric vertebral osteomyelitis and more generally the need for clinicians to pursue their clinical suspicion in the face of false negative results to make an accurate and timely diagnosis.

Acute hematogenous pelvic osteomyelitis: appropriate timing for magnetic resonance imaging

BACKGROUND

The precise time of appearance of bone marrow edema in acute hematogenous pelvic osteomyelitis (AHPO) is unknown. The purpose of the present research is to clarify the time of appearance of bone marrow edema on magnetic resonance imaging (MRI) in AHPO. Our hypothesis was that onset is slower than in long-bone osteomyelitis.

METHODS

We selected 12 patients (mean, 11.8 years) with MRI findings and clinical diagnosis of AHPO. The signal ratios of bone marrow (BM) and gluteus maximus muscle (M, BM/M ratio) in fat-suppressed T2- and T1-weighted images (T2WI, T1WI) were calculated to evaluate changes in bone-marrow signals. The correlation between BM/M ratios and days from onset was evaluated statistically and compared with lower extremity osteomyelitis.

RESULTS

Bone marrow/M ratio of T2WI increased over time after the onset of the primary symptom in all patients and showed a statistically positive correlation (r = 0.36). In seven patients in whom an MRI scan was conducted twice, all showed higher values for the second MRI, and changes were more pronounced over time. The mean BM/M ratio of T2WI was 4.1 when 7 days or less had elapsed from the primary symptom, and 6.4 when more than 7 days had elapsed. The BM/M ratios in the sacroiliac joint group were lower than in the non-sacroiliac joint group.

CONCLUSIONS

Unlike long-bone osteomyelitis, it took 1 week before findings for AHPO became fully evident. A definitive diagnosis can be made in patients with suspected sacroiliitis by performing a further MRI scan at 7 days or later.

Use of Magnetic Resonance Imaging for Orthopedic Trauma and Infection in the Emergency Department

Conditions affecting the musculoskeletal system constitute a significant portion of medical emergencies in the United States, with traumatic injury and infection being two of the most common etiologies. Although physical examination and plain radiographs are often sufficient to guide diagnosis and treatment, there are myriad traumatic and infectious pathologies that are commonly missed or simply not detectable on plain radiographs. Advanced imaging is subsequently warranted for additional workup.Magnetic resonance imaging (MRI) has become an increasingly used imaging modality for musculoskeletal complaints in the emergency department due to its superior visualization of soft tissues, focal edematous changes, and occult osseous insults often not visible on plain radiographs. Although multiple studies have evaluated its utility in the workup of emergency musculoskeletal complaints, there remains a dearth of literature examining the use of MRI for certain occult diagnoses.Radiologists, emergency clinicians, and orthopedic surgeons must be knowledgeable of the indications for MRI in the emergency setting, as delayed diagnosis may contribute to increased morbidity and possibly mortality. This review summarizes the use of MRI in diagnoses relating to trauma or infection among patients presenting to the emergency department with a musculoskeletal complaint.

Musculoskeletal MRI of Nontraumatic Emergencies

A wide range of nontraumatic musculoskeletal conditions may require emergent or urgent management to avoid adverse clinical outcomes. These entities include bone and soft tissue infections, tissue necrosis, impending pathologic fracture or fungating tumor, and pseudoaneurysms. In this review, the magnetic resonance imaging appearance of these various entities is presented and discussed with the aim of improving radiologist and clinician recognition of the importance of key imaging findings in each case.

Characteristics of Pyogenic Musculoskeletal Infections in Older Children and Adolescents

The characteristics and clinical consequences of pyogenic bone and joint infections in older children and adolescents have received little attention. This study evaluated the presentation and complications of musculoskeletal infections involving the pelvis and extremities in children older than 10 years. Thirty patients 10 to 17 years old (mean, 12.7 years old) were treated for musculoskeletal infections. Mean time to diagnosis was 9.2 days. Prior to correct diagnosis, 83% were assessed by at least 1 outpatient provider. At the time of admission, 55% were weight bearing and 93% were afebrile. Twenty-eight percent had a multifocal infection. More than one-third had serious medical complications or orthopedic sequelae; compared with patients without complications, this group had a significantly higher admission C-reactive protein and longer hospital stay. Symptoms of musculoskeletal infection common among young children may be absent in adolescents. Axial imaging is recommended to identify adjacent or multifocal disease. The Kocher criteria are less sensitive for septic hip arthritis in the adolescent population. Prompt recognition and treatment are critical to avoid medical and musculoskeletal complications. [Orthopedics. 2020;43(4):e291-e298.].

High-resolution bimodal imaging and potent antibiotic/photodynamic synergistic therapy for osteomyelitis with a bacterial inflammation-specific versatile agent

Unsatisfactory diagnosis and therapy of osteomyelitis are still common but challenging issues for clinicians. To overcome these problems, a bacterial inflammation-specific multifunctional agent, denoted bovine serum albumin-manganese dioxide-ubiquicidin_29-41-indocyanine green (ICG) -gentamicin (BMUIG), was synthesized for combined high-resolution bimodal imaging and antibiotic/photodynamic therapy for osteomyelitis. BMUIG binding affinity and antibacterial ability were assessed by using Staphylococcus aureus (S. aureus). Photoacoustic/magnetic resonance imaging was performed on a mouse model of acute osteomyelitis after intravenous injection of BMUIG. Then, myelitis-bearing mice were treated with antibiotic/photodynamic combination therapy. BMUIG specifically targeted S. aureus in comparison with non-targeted agents. In the osteomyelitis model, the infection area was identified accurately and quickly through ICG-based photoacoustic imaging and Mn²⁺-based T₁ magnetic resonance imaging after injection of BMUIG. Furthermore, the manganese dioxide in BMUIG reacted with the locally produced hydrogen peroxide under acidic inflammatory conditions, continuously generating oxygen for enhanced photodynamic therapy. In combination with low-dose gentamicin, a synergistic antibacterial effect was observed and bone infection was resolved. In summary, a non-invasive accurate diagnosis and effective synergistic therapy for osteomyelitis was successfully developed using a bacterial inflammation-specific versatile agent, which would provide a sound theranostic strategy for common infectious diseases. STATEMENT OF SIGNIFICANCE: Osteomyelitis is one of the most serious consequences in orthopedics. However, its inaccurate diagnosis and low-effective antibiotic treatment are still common but challenging issues for clinicians. To overcome these problems, we uniquely designed a bacterial inflammation-specific multifunctional nanoagent, bovine serum albumin-manganese dioxide-ubiquicidin_29-41-indocyanine green-gentamicin (BMUIG), for high-resolution bimodal imaging and antibiotic/photodynamic combined therapy of osteomyelitis. Herein, high-resolution imaging technologies refer to classic magnetic resonance imaging and emerging photoacoustic imaging. Photodynamic therapy is subtly introduced because of its safe and effective killing mechanism, which can synergize the bactericidal effect of antibiotics. As a result, we successfully realize non-invasive accurate diagnosis and effective synergistic therapy for osteomyelitis by virtue of the bacterial inflammation-specific versatile agent, which will serve as a promising candidate for sound theranostics in common infectious diseases.

Diagnosis and Management of Infectious Arthritis in Children

PURPOSE OF REVIEW

Septic arthritis is limb and life-threatening condition which necessitates rapid diagnosis and treatment. It is important for a medical practitioner to be familiar with this condition. This review summarizes the epidemiology, risk factors, diagnosis and differential diagnosis, complications, as well as treatment and the following-up of this condition.

RECENT FINDINGS

Different causative organisms require unique diagnostic and treatment approaches. Establishing the diagnosis often requires multiple diagnostic modalities, some of which are new and innovative. Differential diagnosis requires excluding non-infectious inflammatory causes, such as reactive arthritis, juvenile rheumatoid arthritis, transient synovitis, and pericapsular pyomyositis. There is no consensus regarding the nature or duration of pharmacological or surgical treatment. Treatment includes administration of appropriate antimicrobial therapy and including the use of steroids and drainage. The most common complications are osteonecrosis of the femoral head and chronic osteomyelitis. Complications of septic arthritis are mostly due to a missed diagnosis. Further studies are required to better evaluate the diagnostic and therapeutic choice.

The challenge of differentiating vaso-occlusive crises from osteomyelitis in children with sickle cell disease and bone pain: A 15-year retrospective review

PURPOSE

The paediatric sickle cell disease (SCD) osteomyelitis (OM) incidence is 0.3% to 12%. Differentiating vaso-occlusive crises (VOC) from OM is a diagnostic challenge, with limited evidence guiding management. We present a 15-year review of a paediatric sickle cell cohort. We aim to identify OM incidence and provide a management protocol for these children presenting with bone pain.

METHODS

A prospective database of children with haemoglobinopathies (2002 to 2017) was analyzed for temperature, C-reactive protein (CRP) and white cell count (WCC) on admission as well as imaging, treatment and cultures. OM diagnosis was supported by imaging and blood cultures. VOC was defined as bone pain that improved without antibiotics.

RESULTS

Over 15 years, 96 children with SCD presented 358 times to hospital. Empirical antibiotics were given in 308 presentations. There were five cases of OM (1.4%); two acute and three chronic. In all, 50 presentations of VOC were identified. No significant differences in age were noted between the OM and VOC group. Temperature and CRP were significantly elevated in the OM group with no significant difference in WCC. Cultures were only positive in the chronic OM admissions. There were no cases of septic arthritis. No surgical intervention was required.

CONCLUSION

In children with SCD presenting with persistent bone pain, fever, elevated CRP and WCC, OM should be suspected and prompt antibiotic treatment started. Our treatment pathway was successful avoiding OM in 98.6% and septic arthritis in 100%. Further research on novel biological markers distinguishing OM from VOC should be investigated.

LEVEL OF EVIDENCE

III.

High prevalence of bacteria in clinically aseptic non-unions of the tibia and the femur in tissue biopsies

PURPOSE

There are several hints that bacterial colonization might be an often overseen cause of non-union. Modern procedures like PCR have been reported to diagnose bacterial colonization with a high degree of accuracy. While PCR is not ubiquitously available, we hypothesize that biopsies from the non-union site are comparable to PCR results reported in the literature.

METHODS

Retrospective analysis of microbiological results of biopsies from non-unions (femoral or tibial, history of revision surgery, and/or open fracture) with stable osteosynthesis, no clinical signs of local infection were analysed. CRP and leucocyte count were taken on admission. Multiple tissue samples (soft tissue and bone) were from the non-union (1-4 cm incision). Samples were cultivated for 2 weeks and tested following EUCAST protocols using VITEK^® 2.

RESULTS

11 tibia- and 7 femur non-union (44 ± 23.9 years), 11 open fractures (1 I°, 6 II°, 4 III° Gustillo Anderson), 0-5 revisions, and 4.1 (± 1.8) tissue samples were taken 8.5 (± 1.7) months after trauma. Cultures were positive in 8/18 (44,4%) (3/18 Propionibacterium acnes, 1/18 S. capitis, and 4/18 S. epidermidis). There was neither a correlation between number of biopsies taken and positive culture results (Pearson R: - 0.0503, R² 0.0025), nor between positive culture results and leucocytes counts (Pearson R: - 0.0245, R² 0.0006) or CRP concentration (Pearson R: 0.2823, R² 0.0797).

CONCLUSION

The results confirm that the presence of bacteria in cases with no clinical signs of infection is a relevant issue. The prevalence of bacteria reported here is comparable that reported from cohorts tested with PCR or sonication. In most cases, there was only one positive biopsy, raising the question whether a contamination has been detected. Thus, to better understand the problem, it is necessary to gather more knowledge regarding the sensitivities and specificities of the different diagnostic procedures.

A prospective study of screening for musculoskeletal pathology in the child with a limp or pseudoparalysis using erythrocyte sedimentation rate, C-reactive protein and MRI

PURPOSE

To determine if the detection of musculoskeletal pathology in children with a limp or acute limb disuse can be optimized by screening with blood tests for raised inflammatory markers, followed by MRI.

METHODS

This was a prospective observational study. Entry criteria were children (0 to 16 years of age) presenting to our emergency department with a non-traumatic limp or pseudoparalysis of a limb, and no abnormality on plain radiographs. Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) blood tests were performed. Children with ESR > 10 mm/hr or CRP > 10 mg/L underwent a MRI scan. When the location of the pathology causing the limp was clinically unclear, screening images (Cor t1 and Short Tau Inversion Recovery) of both lower limbs from pelvis to ankles ('legogram') was undertaken. Data was gathered prospectively from 100 consecutive children meeting the study criteria.

RESULTS

In all, 75% of children had a positive finding on their MRI. A total of 64% of cases had an infective cause for their symptoms (osteomyelitis, septic arthritis, pyomyositis, fasciitis, cellulitis or discitis). A further 11% had positive findings on MRI from non-infective causes (juvenile idiopathic arthritis, cancer or undisplaced fracture). The remaining 25% had either a normal scan or effusion due to transient synovitis. ESR was a more sensitive marker than CRP in infection, since ESR was raised in 97%, but CRP in only 70%.

CONCLUSION

In our opinion MRI imaging of all children with a limp and either raised ESR or CRP is a sensitive method to minimize the chance of missing important pathology in this group, and is an effective use of MRI resources. We advocate the use of both blood tests in conjunction.

LEVEL OF EVIDENCE

Level II.

Diagnosis and management of acute osteoarticular infections in children

Acute hematogenous osteomyelitis and septic arthritis are not uncommon infections in children and should be considered as part of the differential diagnosis of limb pain and pseudoparalysis. Most bone infections in children arise secondary to hematogenous seeding of bacteria into bone. The most common pathogens are Staphylococcus aureus and Kingella kingae. Children with septic arthritis should be evaluated promptly by orthopedic specialists for aspiration and possible debridement of concomitant osteomyelitis. Optimal empiric therapy after appropriate cultures continues to be intravenous cefazolin. In most cases, conversion to oral antimicrobials should occur when the patient has clinically improved and has decreasing inflammatory markers. For most uncomplicated cases of osteomyelitis, current recommendations are 3 to 4 weeks of antimicrobial therapy compared with the 6 weeks previously recommended.

Sternoclavicular Joint Infection Presenting as Nonspecific Chest Pain

BACKGROUND

Sternoclavicular joint infection (SJI), to include septic arthritis (SA), is a rare cause of chest pain and is often found in patients with significant risk factors and sources for SA. Most acute care laboratory results lack significant sensitivity to rule out SA. Radiographic findings in common acute care imaging often does not reveal findings of SA and osteomyelitis in the acute phase of the infection.

CASE REPORT

We present a patient without significant risk factors for SA, who initially presented with 3 days of pain to the left chest, left neck and shoulder. He had fever and was treated with a short course of antibiotics for possible pneumonia. His symptoms recurred along with fever 36 days after the initial onset of symptoms and was then diagnosed radiographically with left-sided SJI. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: This case reinforces the need to maintain a broad differential diagnosis in the evaluation for chest pain and pursue advanced imaging, such as magnetic resonance imaging, when the pretest probability of SJI is high, especially in the acute phase of the infection.

Distal Forearm Fracture Open Reduction-Internal Fixation: Sonographic Detection of Hardware Malalignment and Associated Tendon Injuries Missed by Radiography

Tendon injury is a known complication of distal radius fracture plate and screw fixation. Targeted musculoskeletal sonography is uniquely capable of assessing both tendon integrity and hardware abnormalities not recognized on radiographs. Each of the 3 patients described presented with pain after an open reduction-internal fixation following a distal forearm fracture. In each patient, radiographic findings, specifically the hardware position, were interpreted as normal. Important radiographically occult observations were subsequently made with sonography, including 3 proud screws and tendon injuries, all of which required surgical treatment. This case series demonstrates the clinical utility of musculoskeletal sonography in symptomatic patients after distal radius open reduction-internal fixation with negative radiographic findings. In our practice, sonography has been the most useful modality for precluding missing or delaying the diagnosis and treatment of these hardware complications. We advocate its use as an adjunct in any department performing musculoskeletal imaging.

Radiologic Approach to Musculoskeletal Infections

Imaging is often used to establish a diagnosis of musculoskeletal infections and evaluate the full extent and severity of disease. Imaging should always start with radiographs, which provide an important anatomic overview. MRI is the test of choice in most musculoskeletal infections because of its superior soft tissue contrast resolution and high sensitivity for pathologic edema. However, MRI is not always possible. Alternative imaging modalities including ultrasound scan, computed tomography, and radionuclide imaging may be used. This article reviews the individual imaging modalities and discusses how specific musculoskeletal infections should be approached from an imaging perspective.

Multifocal bone and bone marrow lesions in children - MRI findings

Polyostotic bone and bone marrow lesions in children may be due to various disorders. Radiographically, lytic lesions may become apparent after loss of more than 50% of the bone mineral content. Scintigraphy requires osteoblastic activity and is not specific. MRI may significantly contribute to the correct diagnosis and management. Accurate interpretation of MRI examinations requires understanding of the normal conversion pattern of bone marrow in childhood and of the appearances of red marrow rests and hyperplasia. Differential diagnosis is wide: Malignancies include metastases, multifocal primary sarcomas and hematological diseases. Benign entities include benign tumors and tumor-like lesions, histiocytosis, infectious and inflammatory diseases, multiple stress fractures/reactions and bone infarcts/ischemia.

Detecting Chronic Post-Traumatic Osteomyelitis of Mouse Tibia via an IL-13Rα2 Targeted Metallofullerene Magnetic Resonance Imaging Probe

Differential diagnosis of chronic post-traumatic osteomyelitis (CPO) from aseptic inflammation remains challenging, since both pathological processes share similar clinical symptoms. Here we utilized a novel targeted metallofullerene nanoparticle based magnetic resonance imaging (MRI) probe IL-13-TAMRA-Gd₃N@C₈₀(OH)₃₀(CH₂CH₂COOH)₂₀ to detect CPO in mouse tibia via overexpressed IL-13Rα2 receptors. The functionalized metallofullerene was characterized by X-ray photoelectron spectroscopy. Upon lipopolysaccharide (LPS) stimulation, macrophage Raw 264.7 cells showed elevated IL-13Rα2 expression via immunofluorescence staining and increased MRI probe binding via built-in TAMRA fluorescence imaging. Trauma was induced in both tibia of mice and bacteria soaked suture was inserted into the right tibia to initiate infection. During the acute phase (1.5 weeks), luminol-bioluminescence imaging revealed much higher myeloperoxidase activity in the infected tibia compared to the sham. In the chronic phase (4 weeks), X-ray radiography illustrated bone deformation in the infected tibia compared to the sham. With T₁ weighted sequences, the probe clearly exhibited hyperintensity in the infection foci at both acute and chronic phases, which was not observed in the sham tibia. Histological analysis revealed severe bone structural destruction and massive inflammatory cell infiltration in the infected tibia. Immunohistochemistry confirmed abundant expression of IL-13Rα2 in the infection site. In summary, we developed a noninvasive imaging approach to detect and differentiate CPO from aseptic inflammation using a new IL-13Rα2 targeted metallofullerene MRI probe. In addition, for the first time, IL-13Rα2 was investigated as a unique biomarker in the context of osteomyelitis. Our data established a foundation for the translational application of this MRI probe in the clinical differentiation of CPO.

Acute Hematogenous Osteomyelitis in Children

This article discusses the most common organisms associated with acute hematogenous osteomyelitis in children. Magnetic resonance imaging is extremely important in evaluating the extent of the disease process. Osteomyelitis due to methicillin-resistant Staphylococcus aureus can be extremely difficult to treat and eradicate. It spreads quickly and causes local tissue necrosis. It is also associated with other serious sequelae such as deep venous thrombosis and septic pulmonary emboli. A multidisciplinary approach is needed to treat these infections. Hospital stays are often lengthy, complications are frequent, and patients are often critically ill. [Pediatr Ann. 2016;45(6):e204-e208.].