The value of sonography in the detection of osteomyelitis

Ultrasonography for the Detection of Osteomyelitis in Pediatric Patients With Soft Tissue Infection: A Pilot Study

OBJECTIVES

To demonstrate the usefulness of ultrasonography for differentiating soft tissue infections with or without osteomyelitis in pediatric patients who underwent ultrasonography and subsequent magnetic resonance imaging (MRI).

METHODS

Twenty-three patients were classified into 2 groups: 12 patients with and 11 patients without osteomyelitis based on MRI. Osteomyelitis using ultrasound is characterized by the presence of bone cortex irregularity and/or subperiosteal abscess formation. The diagnostic performance of ultrasonography for detecting osteomyelitis and subperiosteal abscess formation was compared with that of MRI. Diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value were calculated with 95% confidence intervals (CIs).

RESULTS

Of 12 osteomyelitis cases, 11 had abnormal bone marrow enhancement (one residual case did not undergo contrast enhancement study) and 5 had subperiosteal abscesses. The diagnostic accuracy of ultrasonography for osteomyelitis was 82.6% (number of correct diagnosis of osteomyelitis/total number = 19/23; 95% CI, 61.2-95.0) and for detecting periosteal abscess was 95.7% (number of correct diagnosis of periosteal abscess/total number = 22/23; 95% CI, 78.1-99.9), respectively. The sensitivity and specificity of ultrasonography for detecting osteomyelitis were 66.7% (95% CI, 34.9-90.1) and 100% (95% CI, 71.5-100), respectively. The sensitivity and specificity of ultrasonography for detecting periosteal abscess were 80% (95% CI, 28.4-99.5), and 100% (95% CI, 81.5-100), respectively. One-third of osteomyelitis cases could not be detected using ultrasonography.

CONCLUSIONS

Ultrasonography may be useful for diagnosing osteomyelitis in pediatric patients; however, the technique appears limited by low sensitivity. However, it is more accurate for diagnosis of periosteal abscess in these patients.

Approach to imaging modalities in the setting of suspected infection

Imaging plays an important role in the workup of musculoskeletal infection, in conjunction with clinical history and physical exam. There are multiple imaging modalities that can be of clinical utility in the setting of suspected infection, each with their own benefits and limitations. Radiography is a low-cost, accessible modality providing a broad osseous overview, but can be insensitive for early osteomyelitis. Ultrasound plays a more limited role in the workup of musculoskeletal infection, but can be useful in the pediatric population or for real-time guidance for joint and soft tissue aspirations. Computed tomography (CT) plays an important role in the timely and accurate diagnosis of critically ill patients in the emergency setting. Its superior soft tissue characterization allows for diagnosis of abscesses, and it can help confirm the clinical diagnosis of necrotizing fasciitis when soft tissue gas is present. Magnetic resonance imaging (MRI) is often the modality of choice in the diagnosis of infection, as its superior contrast resolution allows for clear delineation of the presence and extent of both soft tissue infection and osteomyelitis. Additionally, the use of intravenous contrast and advanced imaging sequences such as diffusion weighted imaging (DWI) further increases the diagnostic utility of MRI in the assessment for infection. Familiarity with the diagnostic utility of each imaging modality will allow the radiologist to appropriately guide imaging workup in the setting of clinically suspected infection.

Abscess pulsatility: a sonographic sign of osteomyelitis

INTRODUCTION

Early diagnosis and aggressive treatment of acute osteomyelitis may improve prognosis and prevent further complications. Sonography is useful in the evaluation of osteomyelitis. It can demonstrate early signs of inflammation, such as soft tissue changes near the affected bone, periosteal thickening, periosteal elevation, and subperiosteal abscess.

CASE PRESENTATION

A 68-year-old female presented to the emergency department with 3 weeks of worsening left lower extremity pain. She was initially seen by urgent care for left shin erythema and swelling and treated for cellulitis with intramuscular ceftriaxone without improvement. On presentation, she was afebrile and hemodynamically stable with erythema, swelling, and tenderness of the left pretibial soft tissues. Her labs revealed leukocytosis and elevated inflammatory markers. Point-of-care ultrasound demonstrated a bidirectional flow of fluid through a disruption in the bone cortex visualized on greyscale imaging and confirmed with color and spectral Doppler. The patient was diagnosed with osteomyelitis and treated with antibiotics and incision and drainage by orthopedic surgery.

DISCUSSION

The unique sonographic finding of pulsatile flow of fluid within an abscess near bone has not been previously described in the literature. The presence of Doppler signal in any fluid other than blood is known as pseudoflow. The presence of pulsatility in this case, which could represent either blood or pseudoflow, drew the ultrasound operator's eye to the cortical defect and lead to the diagnosis of osteomyelitis.

CONCLUSIONS

The sonographic finding of pulsatility in an abscess near bone should raise the concern for communication with the medullary cavity.

Sonographic Features of a Tuberculous Cold Abscess: A Case Report and Literature Review

The use of point of care ultrasound (POCUS) to aid diagnosis of tuberculosis has been investigated in countries where concomitant endemic prevalence of HIV increases the incidence of extrapulmonary tuberculosis (EPTB). In such cases, using a focused assessment with sonography for HIV-associated tuberculosis (FASH) scan has found to be immensely advantageous as a rapid diagnostic tool in low resource settings where other imaging modalities are scarce. The prevalence of EPTB in immunocompetent patients in industrialised countries is growing. Since EPTB can manifest itself in almost any part of the human body, symptomatic patients present with constitutional and non-specific symptoms. In our case, a 44-year-old male presented to the emergency department (ED) with a 3-month history of left-sided chest pain and swelling of the chest wall. Clinical examination revealed a swollen and tender lump above the left first rib. Palpation of the thoracic (T7) vertebral body demonstrated localised pain. POCUS showed a collection of heterogenous material with fluid content and specks of hyperechoic 'ring-like' structures. Further investigations led to the diagnosis of EPTB. The patient was admitted and treated for EPTB where he went on to make a full recovery. This case report highlights the role of integrating POCUS in clinical examination of patients with suspected EPTB, which can expedite its diagnosis and management.

Role of ultrasound in the treatment of pediatric infectious diseases: case series and narrative review

BACKGROUND

Infectious diseases are common in pediatric patients. In these patients, ultrasound is a useful imaging modality that involves no irradiation or sedation and can be performed repeatedly at the patient's bedside. The purpose of this review was to show pediatric cases with infectious disease that used ultrasound to decide the methods of treatment.

DATA SOURCES

Literature review was performed using Pubmed as the medical database source. No year-of-publication restriction was placed. The mesh terms used were: "ultrasound", "sonography", "infectious disease", "treatment", "antibiotics", "surgical intervention", "pediatric", "children", "deep neck abscess", "pyothorax", "empyema", "pneumonia", "urinary tract infection", "intra-abdominal abscess", "soft tissue infection", "septic arthritis", "osteomyelitis", and "surgical site infection".

RESULTS

We presented pediatric case series with infectious diseases, including deep neck abscess, pyothorax and empyema, pneumonia, urinary tract infection, intra-abdominal abscess, soft tissue infection, septic arthritis and osteomyelitis, and surgical-site infection. Ultrasound was useful for evaluating the extent and location of inflammation and abscess and for decision-making concerning surgical intervention.

CONCLUSION

Knowledge of these sonographic findings is important for sonographers during examinations and for physicians when determining the treatment plan and period of antibiotic therapy for infected lesions.

Ultrasonography of the bone surface in children: normal and pathological findings in the bone cortex and periosteum

Ultrasound (US) is widely used in pediatric musculoskeletal pathology at all ages. Although the focus is often on soft tissues, joints and cartilage, the examiner might be confronted with changes in the underlying bone surface that are important to understand and integrate in the diagnosis. This article illustrates the normal US aspects of the cortical bone surface and periosteum, as well as the most common US anomalies seen in infections, trauma and bone tumors in children.

Ultrasound evaluation of inflammation in patients with chronic recurrent multifocal osteomyelitis involving the mandible: report of three cases

Chronic recurrent multifocal osteomyelitis (CRMO) is aseptic and can be diagnosed by excluding other diseases, such as bacterial osteomyelitis, scurvy, metabolic disorders, and malignant diseases; therefore, bone biopsy is usually performed to confirm the diagnosis. To prevent misdiagnosis, the appropriate timing and location for biopsy should be determined from an active phase of inflammation. We presented 3 cases of CRMO involving the mandible: Case 1: A 2-year-old girl diagnosed with CRMO in the chronic phase. A sonogram showed a slightly low echoic area adjacent to the bone cortex. Pathological examination revealed a slight accumulation of leukocytes and plasma cells, as well as predominant fibrous stroma. Case 2: A 9-year-old girl diagnosed with CRMO with massive new osteoid formation. A sonogram showed a massive inhomogeneous low echoic area adjacent to the bone cortex. Pathological examination revealed massive osteoid formation and scattered inflammatory cells infiltration. Case 3: A 3-year-old girl diagnosed with CRMO in the active phase. A sonogram showed a massive hypoechoic area adjacent to the bone cortex and hyperechogenicity associated with a muscular and subcutaneous edema. Pathological examination revealed massive bone destruction and neutrophils infiltration within damaged osteoid. Ultrasound was able to visualize the degree of inflammation in the mandible corresponding to that of the surrounding soft tissue in all 3 cases. Therefore, ultrasound would be useful in determining the appropriate timing and location for bone biopsy.

Bone and Joint Infections: The Role of Imaging in Tailoring Diagnosis to Improve Patients' Care

Imaging is needed for the diagnosis of bone and joint infections, determining the severity and extent of disease, planning biopsy, and monitoring the response to treatment. Some radiological features are pathognomonic of bone and joint infections for each modality used. However, imaging diagnosis of these infections is challenging because of several overlaps with non-infectious etiologies. Interventional radiology is generally needed to verify the diagnosis and to identify the microorganism involved in the infectious process through imaging-guided biopsy. This narrative review aims to summarize the radiological features of the commonest orthopedic infections, the indications and the limits of different modalities in the diagnostic strategy as well as to outline recent findings that may facilitate diagnosis.

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.

Sonography of musculoskeletal infection in children

Musculoskeletal infection, especially in young children, often presents with non-specific clinical signs and symptoms necessitating early imaging to identify the source of infection. While MRI is the investigation of choice to demonstrate bone infection, it is expensive and often requires a general anaesthetic in the young child. Ultrasound can be a useful tool in the initial assessment due to its easy availability and portable equipment. It does not involve ionising radiation and is used to guide aspiration and drainage procedures. This review explains sonographic features of septic arthritis, osteomyelitis, pyomyositis and soft tissue infection in children and highlights advantages and limitations of sonography when assessing the child with suspected musculoskeletal infection.

Point-of-Care Ultrasound in a Child with Chest Wall Pain and Rib Osteomyelitis

BACKGROUND

Diagnosis of acute osteomyelitis in young children can be challenging due to the lack of specific clinical signs and symptoms. Prompt diagnosis and treatment is essential to prevent complications and to improve long-term prognosis and reduce the need for operative intervention. Point-of-care ultrasound (POCUS) may be a useful tool to detect early changes associated with osteomyelitis.

CASE REPORT

A 26-month-old boy presented with 6 days of fever and 3 days of focal pain over the right anterior lower ribs without swelling, erythema, or bony deformity, and negative chest x-ray study. A POCUS was performed by the ultrasound fellows and revealed deep soft tissue swelling, periosteal elevation, and increased vascular flow with color Doppler. The patient was admitted to the pediatric service with infectious disease consultation and started on antibiotics. Magnetic resonance imaging confirmed the diagnosis of a right seventh anterior rib osteomyelitis, and the patient subsequently improved and was discharged home. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: In this case, the use of POCUS in the emergency department heightened the suspicion for acute osteomyelitis in a rare location and guided early diagnosis and treatment.

Can ultrasound differentiate acute erosive arthritis associated with osteomyelitis, rheumatoid arthritis, or gouty arthritis?

AIM

The study intended to determine the specific ultrasonographic features of acute arthritis with periarticular bone erosions caused by acute osteomyelitis (OM), rheumatoid arthritis (RA) and gouty arthritis (GA).

METHOD

We included 33 patients (seven with acute OM, 18 with RA flares, and eight with GA attacks) having acute monoarthritis or oligoarthritis, and receiving ultrasound (US) examinations in the acute stage. The US images were rated by three rheumatologists blinded to the diagnosis. The median scores of their evaluation of the subcutaneous tissue, periosteum, and synovium were compared. Interrater reliability was calculated using Cronbach's alpha.

RESULTS

The highest mean grade of subcutaneous edema appeared in patients with acute OM, and grade 2 edema was more frequent than patients with RA and GA (P = .003 and P = .026, respectively; α = .869). The prevalence of subcutaneous power Doppler signal was also higher in patients with acute OM than in those with RA and GA (P < .001 and P = .041, respectively; α = .756). Periosteal vascularity presented more frequently in acute OM (P = .003 compared with RA; P = .041 compared with GA), but the interrater reliability was poor (α = .518). The tophaceous material in GA was distinctive from OM and RA (P = .010 and P < .001, respectively; α = .774).

CONCLUSION

The most discriminative US features in this study were the subcutaneous tissue changes in addition to the periosteal findings. US could contribute to the differential diagnosis of acute erosive arthritis.

Ultrasound Features of the Normal and Pathologic Periosteum

Thickening and elevation of the periosteum from the underlying bone cortex, defined as a periosteal reaction, can be associated with several bone disorders. Although ultrasound (US) has limited possibilities in assessing bones, it can depict a periosteal reaction earlier than plain radiography, thus indicating underlying bone disorders. This pictorial essay aims to illustrate the normal and pathologic US appearances of the periosteum in both children and adults. Several disorders are discussed, such as pediatric bone trauma, infections and tumors, as well as trauma, overuse, including medial tibial stress syndrome, and finally certain seronegative spondyloarthropathies in adults. Whenever US depicts a periosteal reaction, a correlation with clinical and laboratory data is mandatory to differentiate different bone disorders. Computed tomography or magnetic resonance imaging must be performed when an infection or a tumor is suspected based on both US and the clinical presentation.

US Evaluation of Juvenile Idiopathic Arthritis and Osteoarticular Infection

Juvenile idiopathic arthritis (JIA) and osteoarticular infection can cause nonspecific articular and periarticular complaints in children. Although contrast material-enhanced magnetic resonance imaging is the reference standard imaging modality, musculoskeletal ultrasonography (US) is emerging as an important adjunct imaging modality that can provide valuable information relatively quickly without use of radiation or the need for sedation. However, diagnostic accuracy requires a systemic approach, familiarity with various US techniques, and an understanding of maturation-related changes. Specifically, the use of dynamic, Doppler, and/or multifocal US assessments can help confirm sites of disease, monitor therapy response, and guide interventions. In patients with JIA, ongoing synovial inflammation can lead to articular and periarticular changes, including synovitis, tenosynovitis, cartilage damage, bone changes, and enthesopathy. Although these findings can manifest in adult patients with rheumatoid arthritis, important differences and pitfalls exist because of the unique changes associated with an immature and maturing skeleton. In patients who are clinically suspected of having osteoarticular infection, the inability of US to evaluate the bone marrow decreases its sensitivity. Therefore, the US findings should be interpreted with caution because juxtacortical inflammation is suggestive, but neither sensitive nor specific, for underlying osteomyelitis. Similarly, the absence of a joint effusion makes septic arthritis extremely unlikely but not impossible. US findings of JIA and osteoarticular infection often overlap. Although certain clinical scenarios, laboratory findings, and imaging appearances can favor one diagnosis over the other, fluid analysis may still be required for definitive diagnosis and optimal treatment. US is the preferred modality for fluid aspiration and administering intra-articular corticosteroid therapy. ^© RSNA, 2017.

Sonography of pediatric superficial lumps and bumps: illustrative examples from head to toe

Superficial lumps and bumps are extremely common in children, and the vast majority ultimately prove to be benign. Duplex/color Doppler ultrasound (US) has emerged as the first-line imaging modality for the evaluation of these superficial pediatric masses because it provides a means for rapid acquisition of information including size, shape, location, internal content and vascularity. More important, it does so without utilizing radiation, iodinated contrast material or sedation/anesthesia. In this review, we present the sonographic findings of a variety of cases ranging from head to toe that are either uncommonly seen or were diagnosed in an atypical fashion (i.e. ultrasound). In situations where the lesion is too deep, hyperechoic or large to be fully assessed within the field of view or if malignancy is suspected, then additional cross-sectional imaging is warranted for further evaluation.

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.

Nuclear Medicine Imaging in Pediatric Infection or Chronic Inflammatory Diseases

In this review article, we focus on the most recent applications of nuclear medicine techniques (mainly ^99mTc/¹¹¹In white blood cells (WBC) scan, [¹⁸F]-FDG-PET/CT, [¹⁸F]-FDG-PET/MRI, and ^99mTc-IL-2 scintigraphy) in the study of children affected by peripheral bone osteomyelitis, fungal infections, inflammatory bowel diseases, and type 1 diabetes, owing to recent important published evidences of their role in the management of these diseases. For osteomyelitis in children, both bone scintigraphy and [¹⁸F]-FDG-PET have a major advantage of assessing the whole body in one imaging session to confirm or exclude multifocal involvement, whereas WBC scan has a limited role. In children with fungal infections, [¹⁸F]-FDG-PET can help in defining the best location for biopsy and can help in evaluating the extent of the infection and organs involved (also sites that were not yet clinically apparent), although its main role is for therapy monitoring. In inflammatory bowel diseases, and Crohn disease in particular, WBC scan has been successfully used for many years, but it is now used only in case of doubtful magnetic resonance (MR) or when MR cannot be performed and endoscopy is inconclusive. By contrast, there is an accumulating evidence of the role of [¹⁸F]-FDG-PET in management of children with Crohn disease, and PET/MR could be a versatile and innovative hybrid imaging technique that combines the metabolic information of PET with the high soft tissue resolution of MR, particularly for distinguishing fibrotic from active strictures. Finally, there are several new radiopharmaceuticals that specifically target inflammatory cells involved in the pathogenesis of insulitis aiming at developing new specific immunotherapies and to select children candidates to these treatments for improving their quality of life.

A Rare Full-Term Newborn Case of Rib Osteomyelitis with Suspected Preceding Fracture

Acute osteomyelitis is uncommon in full-term neonates and occurs most frequently in those with critical illnesses, often following episodes of sepsis, skin infection, umbilical catheterization, urinary tract anomalies, or a complicated delivery. Here, we report a very rare case of acute rib osteomyelitis due to Staphylococcus aureus in a 13-day-old full-term male neonate. Ultrasonography (US) enabled diagnosis and revealed a coexisting costochondral junction rib fracture, which was not detected on routine chest radiography. Following a 29-day course of intensive parenteral antibiotic therapy, the patient was discharged in good health at 42 days of age without any scar formation. Due to its accessibility and safety, US can be a promising modality for detecting acute osteomyelitis in neonates with clinically highly suspected conditions in the neonatal intensive care unit setting, particularly those involving thin and mobile bones subject to respiratory motion. However, further studies are required to assess the utility of US in these cases and negative results. In low-risk neonates with osteomyelitis, an accompanying fracture should be considered.

Applications of musculoskeletal ultrasonography in pediatric patients

Ultrasonography is an excellent adjunct to other musculoskeletal imaging tools utilized in the pediatric population and in some instances offers advantages over CT and MRI. It permits dynamic examination of anatomic structures and assists in guiding minimally invasive procedures. In the lower extremity, ultrasonography assists in screening for such disorders as developmental dysplasia of the hip and in detecting slipped capital femoral epiphysis and femoral acetabular impingement. In the neonatal spine, ultrasonography can identify unossified vertebral arches. Among other applications in the upper extremity, ultrasonography may be used in the evaluation and examination of peripheral nerve injuries and is a preferred modality for imaging the shoulder in infants with neonatal brachial plexus palsy. It is also considered an optimal adjunct for administration of botulinum toxin-A in children with cerebral palsy. The portability, relative low cost, lack of radiation, and absence of known contraindications enhances the utility of ultrasonography in pediatric orthopaedics.

Panton-Valentine leukocidin-positive Staphylococcus aureus osteomyelitis of the tibia in a 10-year-old child

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is increasing in prevalence among asymptomatic carriers and in cases of paediatric soft-tissue infections alike. CA-MRSA may express virulence factors such as Panton-Valentine leukocidin, which makes soft-tissue and hard-tissue infections due to such organisms challenging to treat. We report a case of osteomyelitis of the proximal tibia in a 10-year-old boy and discuss its management in what is to the authors' knowledge the first case report of Panton-Valentine leukocidin-positive CA-MRSA osteomyelitis in a child in the UK.

Water-bath method for sonographic evaluation of superficial structures of the extremities in children

High-resolution sonography using a stand-off pad or a gel mound is a standard technique for the evaluation of soft-tissue structures of the hands and feet in children. However, the complex curved surfaces of the hands and feet often yield suboptimal contact between the transducer and the skin. Additionally, the small field of view, relative compressibility of the soft-tissue structures by the transducer, patient motion and discomfort from contact of the transducer with the pathology often limit conventional US evaluation. A water-bath technique overcomes these limitations. We present our experience of water-bath technique of superficial sonography in 23 children. Water-bath technique was performed with good patient cooperation and was superior to the standard technique for depiction of shallow skin ulcers, subcutaneous masses, vascular malformations, osteomyelitis and foreign bodies.

Cephalhematoma infected by Escherichia coli presenting as an extensive scalp abscess

Cephalhematoma is normally a self-limiting condition affecting 1%-2% of live births, especially following instrumental forceps delivery. The sub-periosteal bleed is characteristically limited by the cranial sutures. Although benign in most instances, this condition may, in a small proportion of cases, be complicated by hyperbilirubinemia or scalp infection. We describe a case of cephalhematoma in a newborn infant infected with Escherichia coli resulting in an extensive deep seated scalp abscess. The infection was also systemic causing E. coli septicemia and initial assessment assumed local extension including bone and meningeal to cause skull osteomyelitis and meningitis respectively. Further investigations and multiple-modality imaging with ultrasound, CT scan and bone scintigraphy outlined the involvement as limited to the scalp, resulting in a shorter antibiotic treatment period and earlier discharge from hospital. The infant recovered well with parenteral antibiotics, saucerization of the abscess and a later skin grafting procedure.

Ultrasound of the pediatric chest

Historically, the evaluation of the pediatric chest has been accomplished via CT and conventional radiography. Our objective is to discuss and illustrate the role of US as a non-ionizing radiation alternative in the evaluation of the pediatric chest. US is a valuable tool in the evaluation of the pediatric chest. It can be used as a first-line modality in the evaluation of superficial lumps and bumps of the chest wall, diaphragmatic motion, the thymus and pleural effusions, and it can play a valuable secondary role in evaluation of mediastinal masses and pulmonary parenchymal disease.

Pediatric osteomyelitis: a scintigraphic case-based review

This review presents techniques to optimize bone scintigraphy for evaluation of the spectrum of abnormalities associated with pediatric osteomyelitis, with an emphasis on the approaches to patient preparation and positioning and to interpretation. The diagnosis of pediatric osteomyelitis can be challenging for several different reasons. Bone scintigraphy is especially useful when the site of osteomyelitis is unclear. Other imaging modalities, including radiography, ultrasonography, and magnetic resonance imaging, all have advantages and may have a role in evaluating the condition of the child with osteomyelitis. Pathophysiologic considerations unique to children contribute to a different clinical presentation of osteomyelitis in the pediatric population than that seen in adults. In addition, patient movement degrades image quality substantially, which is an important consideration for imaging children. Neonates have a higher incidence of multifocal osteomyelitis, and they represent a unique subset of the pediatric population with separate considerations. Several examples illustrate techniques to optimize imaging, as well as show the spectrum of abnormalities associated with pediatric osteomyelitis. Careful attention to bone scintigraphic technique ensures that high-quality images can be obtained, which will allow confident diagnosis of pediatric osteomyelitis.

The role of diagnostic imaging in the evaluation of suspected osteomyelitis in the foot: a critical review

The early diagnosis of osteomyelitis in the foot from its clinical presentation alone can be difficult particularly in cases when the early signs are subtle. Early diagnosis and subsequent early intervention are imperative to reduce the risk of chronic infection, associated early lytic changes to bone and potential long term structural complications caused by subsequent deformity and lost anatomy. Diagnostic imaging has a major role to play in the early assessment and diagnosis of bone infection, yet the choice of approach can be controversial. Several imaging modalities have been advocated, imaging of the infected foot is complex and no single test is ideal for every situation. The clinician needs to be aware of the strengths and weaknesses of each imaging modality so that the most appropriate test is selected for the individual case. Factors such as site of infection in the foot, the aggressive nature of the organism, the time since onset, previous associated surgery and co-morbidity may all play apart in the clinician's decision making process to determine the best approach in detecting the sometimes subtle changes which may be seen in some cases of osteomyelitis. This review considers the literature and highlights the advantages and disadvantages of the main imaging techniques used for the evaluation of the foot when osteomyelitis is suspected. An evidence based algorithm for the selection of appropriate imaging techniques is suggested to aid clinicians in there decision making process.

Paediatric musculoskeletal US beyond the hip joint

US is a technique particularly suited to the investigation of musculoskeletal disorders in children and adolescents. This review paper describes a range of clinical settings beyond the hip joint where US has a significant role to play, including sports injuries, infectious diseases, inflammatory and degenerative conditions, congenital and developmental disorders, acute trauma of bone and joints, and peripheral nerve injuries. In some circumstances, US can be regarded as the most effective means of diagnostic imaging, whereas in other instances, it is an alternative or supplement to other more comprehensive imaging modalities, like MRI and CT. Although MRI offers superior soft-tissue contrast resolution, US is low-cost, non-invasive and has higher spatial resolution and real-time capability for the assessment of musculoskeletal structures during joint movement and stress manoeuvres.

Gray-scale and color Doppler ultrasonographic evaluation of reactivated post-traumatic/postoperative chronic osteomyelitis

OBJECTIVE

We aimed to carry out a systematic assessment of gray-scale and color Doppler ultrasonography (CDUS) findings of reactivated post-traumatic/postoperative chronic osteomyelitis (COM) in adults.

MATERIALS AND METHODS

Gray-scale and color Doppler ultrasonography were performed on 40 consecutive patients with a history of long-standing post-traumatic/post-operative chronic osteomyelitis and clinical suggestion of reactivation, in a 32-month-period. All patients had metallic implants: 16 internal fixations, nine external fixations, 11 hip arthroplasties and four knee arthroplasties. The final diagnosis of reactivated COM was based upon biopsy findings, with microbiological and histological examination (n = 27), or a combination of laboratory, clinical and magnetic resonance (MR) findings (n = 13). The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of sonographic signs, including fistulous tracts, periosteal thickening, cortical discontinuity, soft tissue abscess and cellulitis, juxtacortical fluid, distension of the pseudocapsule in arthroplasties, and periosteal vascularity, were estimated.

RESULTS

Statistically significant differences between patients with and without reactivated COM were found for fistulous tracts (P < 0.0001), juxtacortical fluid collections (P < 0.001) periosteal thickening (P < 0.01), distension of pseudocapsule (P < 0.05), and periosteal vascularity (P < 0.0001). Low-resistance arterial flow of periosteal vessels presented the highest sensitivity (92%), specificity, and PPV (100%), yielding only two false negative results in two obese patients. Among gray-scale findings, the presence of a fistulous tract yielded the highest specificity and PPV (100%), whereas periosteal thickening was the most sensitive (92%), though not specific, finding (specificity 50%).

CONCLUSION

A constellation of gray-scale and CDUS findings can be highly indicative of reactivated bone infection in patients with long-standing chronic post-traumatic/post-operative osteomyelitis.

Current concepts in imaging diabetic pedal osteomyelitis

Diabetic pedal osteomyelitis is primarily a manifestation of vascular insufficiency with resultant tissue ischemia, neuropathy, and infection. Nearly all cases of pedal osteomyelitis arise from a contiguous ulcer and soft tissue infection. MR imaging is the modality of choice to assess for the presence of osteomyelitis and associated soft tissue complications, to guide patient management, and to aid in limited limb resection.

Role of power Doppler sonography in early diagnosis of osteomyelitis in children

We describe 2 children complaining of leg pain associated with elevated C-reactive protein levels in whom power Doppler (PD) sonography suggested the diagnosis of early osteomyelitis. PD sonography detected increased blood flow that resulted in a high-intensity signal area adjacent to the symptomatic tibia surface. Antibiotic therapy led to prompt improvement. These cases suggest that PD sonography is useful in the evaluation of possible early osteomyelitis in children.

Imaging of osteomyelitis: current concepts

Osteomyelitis frequently requires more than one imaging technique for an accurate diagnosis. Conventional radiography still remains the first imaging modality. MRI and nuclear medicine are the most sensitive and specific methods for the detection of osteomyelitis. MRI provides more accurate information regarding the extent of the infectious process. Ultrasound represents a noninvasive method to evaluate the involved soft tissues and cortical bone and may provide guidance for diagnostic or therapeutic aspiration, drainage, or tissue biopsy. CT scan can be a useful method to detect early osseous erosion and to document the presence of sequestra. PET and SPECT are highly accurate techniques for the evaluation of chronic osteomyelitis, allowing differentiation from soft tissue infection.

Imaging of musculoskeletal infections

Imaging procedures are routinely used to evaluate patients suspected of having musculoskeletal infection. Radiographs should be performed whenever musculoskeletal infection is suspected. Even when not diagnostic, radiographs are useful. They provide an anatomic overview of the region of interest, including pre-existing conditions that could influence the selection and interpretation of subsequent procedures. Magnetic resonance imaging (MRI) is sensitive, provides superb anatomic detail, does not use ionizing radiation, and is rapidly completed. This technique is especially valuable for septic arthritis, spinal osteomyelitis, and diabetic foot infections. Among the radionuclide procedures, three-phase bone imaging is readily available, and very accurate in unviolated bone. Labeled leukocyte imaging should be used in cases of 'complicating osteomyelitis' such as prosthetic joint infections. This test is also useful in unsuspected diabetic pedal osteomyelitis and the neuropathic joint. Gallium imaging is a useful adjunct to MIR in spinal infection. 18F-2-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) will likely play an important role, especially in the evaluation of spinal infection.

Osteomyelitis: clinical update for practical guidelines

Bone infections represent a diagnostic or therapeutic challenge for the infectivologist, orthopaedic surgeon, radiologist and nuclear medicine physician. Staphylococcus aureus is the major bacterium responsible for bone infections although Mycobacterium tuberculosis is emerging as an infectious agent in Italy because of immigration from Africa and Asia. Osteomyelitis requires long and expensive antibiotic treatment, including rifampicin administered parenterally for several weeks and the use of antimicrobial-impregnated cement in prosthesis substitution. Sometimes it is necessary to carry out surgical debridement of a necrotic bone or the consolidation of compromised bones and joint prosthesis implants. Radiographs and bone cultures are mainstays for the diagnosis of bone infections but are often useless in the lengthy management of these patients. Diagnosis of skeletal infections still includes conventional radiography but magnetic resonance imaging is essential in haematogenous and spinal infections. Bone scans are still useful in acute osteomyelitis whereas scintigraphy using labelled white blood cells is preferred in infections of peripheral bone segments or joint prosthesis. In the axial skeleton a combination of an agent for detecting inflammation ((67)Ga citrate) and a metabolic agent ((99m)Tc-methylene diphosphonate) enables an infection and an area of increased metabolic activity to be distinguished. [(18)F]Fluorodeoxyglucose positron emission tomography, where available, has a significant impact in the study of infections using radionuclides: high-resolution tomographic images represent an effective alternative to gallium in the assessment of inflammation of spine lesions but a comparison with morphological examinations (computed tomography or magnetic resonance imaging) is essential.

Diagnostic imaging of pediatric hematogenous osteomyelitis: lessons learned from a multi-modality approach

Pediatric hematogenous osteomyelitis may present highly variable radiological expression, which is influenced by the age and condition of the patient, the virulence of the causative agent, the stage of the disease, or the selected imaging tool. Given the multiplicity of available modalities and the multi-faceted nature of the process, purposeful imaging of pediatric hematogenous osteomyelitis may be difficult. In order to avoid diagnostic delays and complications, familiarity with the variable expression of the disease and assumption of the potentialities, roles and limitations of the various imaging modalities is required. In this pictorial essay we review, illustrate and discuss, in a multi-modality approach, the various radiological patterns that may be found in pediatric hematogenous osteomyelitis, with emphasis on strategies, staging, uncommon distribution patterns, and differential diagnosis.

Acute osteomyelitis as a complication of varicella

Varicella is a common viral infection in childhood, and acute osteomyelitis is one of the rare but serious complications. We report two cases of osteomyelitis as a complication of varicella. The possibilities and limitations of the different imaging modalities are discussed, as well as imaging findings during the course of this condition.

Musculoskeletal infections: ultrasound appearances

Musculoskeletal infections are commonly encountered in clinical practice. This review will discuss the ultrasound appearances of a variety of musculoskeletal infections such as cellulitis, infective tenosynovitis, pyomyositis, soft-tissue abscesses, septic arthritis, acute and chronic osteomyelitis, and post-operative infection. The peculiar sonographic features of less common musculoskeletal infections, such as necrotizing fasciitis, and rice body formation in atypical mycobacterial tenosynovitis, and bursitis will also be presented.

Orthopedic pitfalls in the ED: osteomyelitis

Osteomyelitis can present to the emergency department as an acute, subacute, or chronic orthopedic concern. The presentation can range from subtle, as with acute hematogenous osteomyelitis in the pediatric patient population, to obvious, as with the diabetic patient who presents with a foot ulcer overlying exposed bone. Accurate early diagnosis and prompt treatment, whether with antibiotics, debridement, or both, are important in helping determine the ultimate outcome in this potential orthopedic pitfall. We review here the clinical presentation, diagnostic techniques, and management options for osteomyelitis that are applicable to the emergency practitioner.

Review article: diagnostic ultrasonography: applications in orthopaedic surgery

Diagnostic ultrasonography of musculoskeletal diseases in the United States has been used most often for detection of rotator cuff tears or developmental dysplasia of the hip. Diagnostic ultrasonography also is useful in imaging the periarticular soft tissues about the knee, hip, ankle, occult pediatric fractures, muscle injury, bone healing, and foreign bodies. Recent technologic improvements have made this imaging modality increasingly more accurate while providing significant benefits over traditional modalities such as magnetic resonance imaging, particularly regarding cost, patient satisfaction, and ease of usage. Increasing use in the future of diagnostic ultrasonography for musculoskeletal conditions is likely as acceptance grows. This review focuses on recent, practical applications of diagnostic ultrasonography of the musculoskeletal system.

Ultrasound in pediatric musculoskeletal disease: techniques and applications

The increased ratio of nonossified cartilage to bone in children makes ultrasound (US) a particularly suitable technique for evaluating pediatric musculoskeletal disorders. US allows the examiner to compare quickly and meticulously an affected to unaffected area of interest in different orthogonal planes without a need for sedation. Developmental dysplasia of the hip is the most common indication for pediatric musculoskeletal US. Sonography is also a cost-effective, useful, and complementary imaging tool for evaluating pediatric musculoskeletal trauma, inflammation-infection, and masses.

Review article: Paediatric bone and joint infection

Paediatric musculoskeletal infection remains an important cause of morbidity. Methicillin sensitive Staphylococcus aureus is still the most common organism although the incidence of methicillin resistant S. aureus in the community is rising. Osteomyelitis and septic arthritis due to Haemophilus influenzae is decreasing in incidence secondary to immunisation and in some units has been replaced by infections with the gram negative bacillus, Kingella kingae. Recent prospective studies indicate that uncomplicated osteomyelitis can be treated by three to four weeks of antibiotics. However, there is still a small group of children who will have overwhelming disseminated infection. These children require aggressive surgical and medical intervention. Two recent reports have identified an increased incidence of septic arthritis in children who have hemophilia and are HIV positive.

Imaging of osteomyelitis in children

Imaging approach to osteomyelitis in children should aim toward a timely and accurate diagnosis in view of the need for prompt therapy to prevent sequelae. One must take advantage of the specific value of each imaging modality and adopt a strategy that works best for a given child in a given institution.

Role of ultrasound in musculoskeletal infections

Ultrasound is able to play a key role in the management of musculoskeletal soft tissue infections. It is an easily accessible imaging modality that can be used immediately after plain radiographs have been obtained. Quick diagnosis is essential in the clinical setting of musculoskeletal infection because delay can lead to significant morbidity. In addition to its diagnostic capabilities, US offers a safe, real-time, and convenient technique to perform immediately a guided-needle aspiration of any suspicious fluid collection. US provides the most efficient way to document quickly an infection of the musculoskeletal soft tissues and to identify the offending micro-organism.

Sonography of acute osteomyelitis in rabbits with pathologic correlation

RATIONALE AND OBJECTIVES

Ultrasonography (US) has a potential role in the diagnosis of osteomyelitis. The purpose of this study was to determine the characteristic sonographic features of acute osteomyelitis and correlate them with pathologic findings.

MATERIALS AND METHODS

An experimental model of acute osteomyelitis was produced in the tibiae of 20 rabbits. Daily US and plain radiography were performed for 2 weeks. The authors evaluated periosteal reaction, subperiosteal fluid collection, and soft-tissue changes seen with US. A hypoechoic band and a hyperechoic line lying along the cortex were considered positive signs of subperiosteal fluid collection and periosteal reaction, respectively. The findings of periosteal reaction were compared for US and radiography, and pathologic findings were also correlated.

RESULTS

The most common sonographic finding was a hypoechoic band along the cortex (21 [75%] of 28 tibiae), usually associated with a linear periosteal reaction (20 [71%] of 28). This juxtacortical abnormal echogenicity corresponded to periosteal elevation with loose fibrovascular connective tissue and granulation, associated with subperiosteal abscess formation. The periosteal reactions were detected with US before they were seen on radiographs. The periosteum showed gradual thickening during the disease process. In 50% of infected tibiae, inflammation or abscess formation was observed in the surrounding soft tissue.

CONCLUSION

US readily demonstrates juxtacortical abnormal echogenicity and soft-tissue infection related to acute osteomyelitis. The abnormal echogenicity correlated well with the pathologic findings of periosteal reaction and subperiosteal abscess.