Pediatric osteomyelitis: a scintigraphic case-based review

Bacterial osteomyelitis in pediatric patients: a comprehensive review

Bacterial osteomyelitis, an inflammatory response in the bone caused by microorganisms, typically affects the metaphysis in the skeletally immature. Bacterial osteomyelitis possesses a significant diagnostic challenge in pediatric patients due to its nonspecific clinical presentation. Because the metaphysis is the primary focus of infection in skeletally immature patients, understanding the normal physiologic, maturation process of bones throughout childhood allows to understand the pathophysiology of osteomyelitis. Timely and accurate diagnosis is crucial to initiate appropriate treatment, and prevent long-term sequelae and efforts must be made to isolate the causative organism. The potential causative organism changes according to the age of the patient and underlying medical conditions. Staphylococcus Aureus is the most common isolated bacteria in pediatric pyogenic osteomyelitis whereas Kingella Kingae is the most common causative agent in children aged 6 months to 4 years. Imaging plays a pivotal role in the diagnosis, characterization, evaluation of complications, and follow up of bacterial osteomyelitis. Imaging also plays a pivotal role in the evaluation of potential neoplastic and non-neoplastic mimickers of osteomyelitis. In children, MRI is currently the gold standard imaging modality when suspecting bacterial osteomyelitis, whereas surgical intervention may be required in order to isolate the microorganism, treat complications, and exclude mimickers.

[Imaging Findings in Pediatric Musculoskeletal Infection and Inflammation]

Infections and inflammatory conditions of immature musculoskeletal systems in pediatric patients also affect the adjacent muscles, connective tissues, and joints. Rapid diagnosis leading to appropriate treatment can significantly impact the occurrence of complications and mortality rates due to these conditions. When a radiologist becomes familiar with the imaging findings of pediatric musculoskeletal infections and inflammatory diseases, rapid differential diagnoses and more timely and appropirate treatment could be possible. In this paper, we introduce the imaging findings of infectious and inflammatory diseases affecting the immature musculoskeletal system, such as osteomyelitis, pyogenic arthritis, juvenile idiopathic arthritis, and hemophilic arthritis, based on the anatomical and pathophysiological characteristics of the immature musculoskeletal system in children.

ACR Appropriateness Criteria® Osteomyelitis or Septic Arthritis-Child (Excluding Axial Skeleton)

Imaging plays an integral role in the evaluation of suspected musculoskeletal infections in children, not only in the accurate identification of infection such as osteomyelitis or septic arthritis, but also in guiding management. Various diagnostic modalities serve different purposes in the assessment of suspected pediatric musculoskeletal infections. The purpose of this document is to provide imaging guidance in the most frequently encountered clinical scenarios in which osteomyelitis and/or septic arthritis are suspected, outside of the axial skeleton. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion.

Clinical Practice Guideline by the Pediatric Infectious Diseases Society and the Infectious Diseases Society of America: 2021 Guideline on Diagnosis and Management of Acute Hematogenous Osteomyelitis in Pediatrics

This clinical practice guideline for the diagnosis and treatment of acute hematogenous osteomyelitis (AHO) in children was developed by a multidisciplinary panel representing Pediatric Infectious Diseases Society (PIDS) and the Infectious Diseases Society of America (IDSA). This guideline is intended for use by healthcare professionals who care for children with AHO, including specialists in pediatric infectious diseases, orthopedics, emergency care physicians, hospitalists, and any clinicians and healthcare providers caring for these patients. The panel's recommendations for the diagnosis and treatment of AHO are based upon evidence derived from topic-specific systematic literature reviews. Summarized below are the recommendations for the diagnosis and treatment of AHO in children. The panel followed a systematic process used in the development of other IDSA and PIDS clinical practice guidelines, which included a standardized methodology for rating the certainty of the evidence and strength of recommendation using the GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach. A detailed description of background, methods, evidence summary and rationale that support each recommendation, and knowledge gaps can be found online in the full text.

Imaging of the limping child

Limping is a challenging symptom in the pediatric patient as the diagnosis can range from traumatic, malformative, infectious/inflammatory and neoplastic diseases. In this paper, we propose a schematic imaging algorithm to the limping child in three different age groups (Toddler: 1-3years, child: 4-10 years; adolescent: 11-16 years) based on presence of signs of infection, any specific localization of pain, and history of trauma. In this setting, the most common imaging pitfalls are also summarised. Finally, a literature review of the main differential causes of limping in the pediatric patient is reported.

Back pain: A puzzle in children

Back pain in children is underdiagnosed and increases incidence in adolescence. A systematic approach can diagnose the most common causes: trauma, structural deformities, inflammatory diseases, infection and malignancy.

The imaging of osteomyelitis

Osteomyelitis is an important cause of morbidity and mortality in children and adults. Imaging plays a crucial role in establishing a timely diagnosis and guiding early management, with the aim of reducing long-term complications. Recognition of the imaging features of osteomyelitis requires a good understanding of its pathogenesis. In this review, the key imaging findings in osteomyelitis are correlated with the underlying pathological processes. There is a particular emphasis on magnetic resonance imaging (MRI), which is the best available imaging modality owing to its high sensitivity for detecting early osteomyelitis, excellent anatomical detail and superior soft tissue resolution. However, other modalities such as nuclear medicine and computed tomography (CT) are also useful in many clinical contexts, and will also be described in this review.

Chronic recurrent multifocal osteomyelitis: A rare entity

INTRODUCTION

Chronic recurrent multifocal osteomyelitis (CRMO) is an auto-inflammatory disease which is characterised by non-infectious bone lesions at multiple sites which have a relapsing nature. Our aim is to examine the role of radiology in diagnosis and management of CRMO patients who have been managed at the Mater Children's Hospital.

METHODS

This is a retrospective analysis of patients who have been managed with CRMO at the Mater Hospital since 2002. Inclusion criteria included a final diagnosis of CRMO. Exclusion criteria were a diagnosis more likely than CRMO. Medical images for each patient were evaluated for lesion features, location of lesion, number of bony lesions and whether or not the radiographic appearance would be characteristic of CRMO.

RESULTS

Initially, 17 patients were included in the study; however, seven patients were excluded due to a more likely alternative diagnosis. In total, 24 lesions were detected; the most common anatomical sites were the spine (25%), feet (25%), ribs (16.7%) and femur (12.5%). Plain radiography lacked sensitivity, but it was important in initial screening and evaluating progress of lesions. MRI is important for targeted investigation and further evaluation of lesions. Bone scintigraphy is useful for detecting other affected sites. Due to the exposure to radiation, computed tomography is generally avoided.

CONCLUSIONS

The combination of imaging modalities plays a large role in CRMO diagnosis. CRMO lesions usually appear ill defined with no pathognomonic features. The distribution of bony lesions can aid diagnosis, with lower limbs and clavicles commonly affected.

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

Osteomyelitis is a significant cause of morbidity in children throughout the world. Multiple imaging modalities can be used to evaluate for suspected osteomyelitis, however magnetic resonance imaging (MRI) has distinct advantages over other modalities given its ability to detect early changes related to osteomyelitis, evaluate the true extent of disease, depict extraosseous spread of infection, and help guide surgical management. MRI has assumed a greater role in the evaluation of osteomyelitis with the increase in musculoskeletal infections caused by methicillin-resistant Staphylococcus aureus which have unique imaging features that are well-demonstrated with MRI. This review focuses primarily on the use of MRI in the evaluation of osteomyelitis in children and will include a discussion of the clinically important and characteristic findings on MRI of acute bacterial osteomyelitis and related conditions.

Osteomyelitis and beyond

Musculoskeletal infections are a cause of considerable morbidity in children. Symptoms and signs are often nonspecific, and imaging is needed to define the anatomical location of infected tissue or fluid collections for diagnostic aspiration or biopsy. Prompt diagnosis and precise localization of the infection site has become even more imperative with the emergence and dissemination of highly invasive organisms such as community-acquired Staphylococcus aureus. Although radiography, bone scintigraphy and US continue to play a role, MRI is now the preferred imaging modality for definitive evaluation of pediatric musculoskeletal infections because of its capability of simultaneously assessing the osseous, articular and muscular structures without ionizing radiation exposure. This article focuses on the imaging characteristics of osteomyelitis, septic arthritis and pyomyositis and the differentiating features of potential mimics of infection.

Childhood osteomyelitis: imaging characteristics

Background

The purpose of this review is to illustrate the imaging findings of childhood osteomyelitis. The diagnosis of childhood osteomyelitis can be challenging. Clinical presentation and laboratory results can differ and are relatively unreliable. To date, its role in the assessment of treatment efficacy is not yet clear.

Methods

This review article provides an overview of the different imaging modalities and imaging characteristics of childhood osteomyelitis. Levels of evidence for different modalities are presented.

Results

Paediatric radiology plays a pivotal role in the diagnosis of childhood osteomyelitis and can also be used to guide therapy and intervention.

Conclusion

Although imaging is essential in the diagnostic process, cooperation between the physician and radiologist remains the cornerstone in accurately diagnosing childhood osteomyelitis.

Main Messages

• Imaging plays a pivotal role in the diagnosis of childhood osteomyelitis.

• Cooperation between the clinician and radiologist is a very important aspect of making the diagnosis.

• The initial imaging modality in childhood osteomyelitis is conventional imaging.

• Normal conventional imaging does not exclude osteomyelitis.