The role of ultrasound in the emergency department evaluation of the acutely painful pediatric hip

Transient/Toxic Synovitis

Transient synovitis (TS) is a self-limiting inflammatory condition of the joints, predominantly affecting children and characterized by symptoms such as pain, swelling, warmth, and erythema. It is often triggered by an immune response to a viral infection, leading to acute inflammatory arthritis. Diagnosis involves a combination of patient history, physical examinations, imaging techniques, and laboratory tests, although there are no specific laboratory tests for TS. Treatment primarily consists of symptom management through rest, analgesics, and nonsteroidal anti-inflammatory drugs. The condition underscores the importance of distinguishing TS from more serious joint diseases to prevent unnecessary interventions and to ensure appropriate management.

[Septic arthritis and transient synovitis of the hip]

CLINICAL/METHODICAL ISSUE

Differentiating between septic arthritis and transient synovitis can be challenging but is very important as a late diagnosis of septic arthritis can lead to sepsis and joint damage. For correct diagnosis and prediction of complications, the right combination of physical examination, laboratory and radiological studies is needed.

STANDARD RADIOLOGICAL METHODS

Hip ultrasound is easy to learn and has a high sensitivity for joint effusion. Faster diagnosis and therapy are possible due to increasing use of ultrasound. Magnetic resonance imaging (MRI) is primarily used to rule out co-infections (osteomyelitis, pyomyositis) and differential diagnoses. X‑ray is typically nonremarkable in septic arthritis.

PRACTICAL RECOMMENDATIONS

Routine use of ultrasound in nontraumatic pediatric hip pain. Generous use of MRI in case of elevated inflammatory markers or inconclusive clinical findings. Using only few sequences may be appropriate to avoid sedation, primarily fluid sensitive sequences (fat-saturated T2, TIRM, STIR), in case of positive findings, accompanied by T1-weighted images.

Transient synovitis of the hip: Current practice and risk of misdiagnosis

INTRODUCTION

Transient synovitis (TS) is a common and benign cause of hip pain in children, but must be distinguished from more serious entities such as septic arthritis, osteomyelitis, and pyomyositis. Our objectives were to determine the risk of missed bacterial musculoskeletal infection and rates of diagnostic testing in children diagnosed with TS.

METHODS

We performed a cohort study using the Pediatric Heath Information System of children 1-10 years diagnosed with TS in the ED. We determined rates of missed bacterial musculoskeletal infection (defined as a new diagnosis of septic arthritis, osteomyelitis, or pyomyositis within 14 days of initial ED visit). We described the initial diagnostic evaluation and ED management of children diagnosed with TS and variability between sites.

RESULTS

We analyzed 6419 encounters from 37 hospitals. 62 (1.0%, 95%CI: 0.7-1.2%) children were diagnosed with a missed bacterial musculoskeletal infection. Children with missed infection were younger than those without (median age 2.6 vs. 4.6 years, p < 0.01). Serum laboratory testing was performed in 76% of encounters with minimal variation across sites. There was significant variation in the rates of hip ultrasound by site (2 to 92%), which has increased in use over time (from 42% in 2016 to 62% in 2021).

CONCLUSION

In this large observational study, missed bacterial musculoskeletal infection in children diagnosed with TS was rare but more common in younger children. The optimal combination of bloodwork and radiographic testing, especially ultrasound, to distinguish TS from more serious disease remains unclear.

Common Ultrasound Applications for Pediatric Musculoskeletal Conditions

PURPOSE OF REVIEW

To discuss the use of ultrasound for diagnosis and management of common pediatric musculoskeletal conditions through a case-based approach.

RECENT FINDINGS

Ultrasound is an essential diagnostic modality in the early detection of developmental dysplasia of the hips and can be used as early as 6 weeks of age when the ossific nucleus has not developed yet. Ultrasound is helpful in diagnosing traumatic injuries such as fractures and intramuscular hematomas, can visualize fracture healing at early stages, and can also be used to guide aspiration of hematomas that can help with decreasing pain and faster recovery. Ultrasound is superior to radiographs in evaluating joint effusions and soft tissue infections or masses and is better tolerated by children compared to other imaging modalities such as magnetic resonance imaging (MRI). Ultrasound is an easily accessible, affordable, non-invasive, and radiation-free imaging modality that is well tolerated by children and their families. It can aid in the diagnosis and management of a wide variety of musculoskeletal conditions including developmental, traumatic, and infectious etiologies, as well as in the evaluation of superficial soft tissue masses.

Point-of-Care Ultrasound-Guided Aspiration of the Hip Joint by an Emergency Medicine Physician: A Pediatric Retrospective Case Series

OBJECTIVES

Early administration of antibiotics is crucial to treating septic hip. This study aimed to describe the clinical course and outcomes of children with septic hip diagnosed using point-of-care ultrasound (POCUS)-guided hip aspirations performed by an emergency medicine physician.

METHODS

A retrospective case series analysis.

RESULTS

Between January 1, 2014, and December 31, 2019, 10 children with septic hip were diagnosed by emergency physicians using POCUS-guided hip aspirations. Six of them were female; the mean age was 4.2 ± 4.5 years, and the mean time from onset of symptoms to diagnosis was 2.9 ± 1.7 days. Seven patients (70%) had a history of fever. All the patients had elevated inflammatory blood markers (white blood cell count >12 K/μL, erythrocyte sedimentation rate >40 mm/h, or a C-reactive protein >2 mg/dL). The mean time from hospital arrival to the first antibiotic dose was 5.2 + 4.0 hours. All the children were discharged fully ambulatory and did not require rehospitalization or repeat aspiration after discharge.

CONCLUSIONS

This case series shows that POCUS-guided hip aspiration is both safe and feasible in diagnosing septic hip in the pediatric emergency department. The procedure enables rapid diagnosis and early initiation of antibiotic treatment, thus reducing the risk for complications related to delayed initiation of therapy.

Yield of Plain Radiography in Addition to Ultrasound Among Children with Hip Pain

BACKGROUND

Children with limp or hip pain often undergo radiographs and ultrasound as part of their initial evaluation. Previous research suggests that hip radiography may have limited utility, and early use of ultrasound may safely reduce the use of radiographs.

OBJECTIVES

We sought to assess the utility of radiography in addition to ultrasound by evaluating the rate of bony abnormalities present on hip radiographs among children with and without effusion on ultrasound. We also assessed the agreement of point-of-care and Radiology-performed ultrasounds for the detection of effusion.

METHODS

This is a retrospective cohort study of children presenting to a pediatric emergency department with acute atraumatic limp or hip pain. Data from patients who received both hip ultrasound and hip radiography as part of their evaluation were analyzed. We included both point-of-care and Radiology-performed hip ultrasounds.

RESULTS

We identified 134 patients who received both hip ultrasound and hip radiographs. Sixty-eight patients (51%) had a hip effusion present on ultrasound and none of these had bony abnormalities on radiography (0%, 95% confidence interval 0-5.3%). Of the 66 patients (49%) who had no effusion on hip ultrasound, 2 patients were found to have a bony abnormality (3%, 95% confidence interval 0.4-10.5%). For patients who received both point-of-care and Radiology-performed ultrasound, the overall agreement for diagnosis of effusion was 92.6% (kappa = 0.82).

CONCLUSIONS

We observed that no children with an effusion on ultrasound had bony pathology on plain radiography, suggesting that the routine performance of hip radiography may not be indicated in all children. Future studies are needed to evaluate the negative predictive value of effusion in larger numbers of patients with known bony abnormalities.

Evaluation of Hip Pain and Management of Toxic Synovitis in the Ultrasound Era

ABSTRACT

The cause of acute onset hip pain in children can be difficult to determine. Once trauma is excluded, the workup revolves around determining whether there is a hip effusion and eliminating orthopedic emergencies. Point-of-care-ultrasound can be used as an adjunct in the workup. In this article, we review (1) differential diagnosis of hip pain, with a focus on toxic synovitis; (2) the evaluation of a hip for the presence of effusion, including the point-of-care ultrasound technique; and (3) the management of toxic synovitis.

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 and the Septic Prosthetic Hip Joint

Septic joints can have an insidious onset and are difficult to diagnosis. Diagnosis can be more complicated in the setting of a distant prosthetic joint. Plain films and inflammatory markers are not specific and magnetic resonance imaging (MRI) is not a timely test in the emergency department. Computed tomography (CT) scan is quick and useful to evaluate for bony changes or signs of inflammation, but lacks the details of MRI, and the prosthetic joint may cause significant artifact. Point-of-care ultrasound (POCUS) is often used in the pediatric population to evaluate for an effusion when there is a concern for a septic native hip joint and is finding a role in adult emergency medicine to evaluate for an effusion in painful native adult hip joints. Even so, ultrasound is not currently included in diagnostic algorithms for diagnosing prosthetic hip joint infections (PJIs). POCUS is, however, readily available in the emergency department. We present a case where POCUS aided in identifying a periprosthetic synovitis and changed the course of the patient's management from previous physical therapy to an investigation toward the final diagnosis of a septic prosthetic hip joint.

ACR Appropriateness Criteria® Acutely Limping Child Up To Age 5

Imaging plays in important role in the evaluation of the acutely limping child. The decision-making process about initial imaging must consider the level of suspicion for infection and whether symptoms can be localized. The appropriateness of specific imaging examinations in the acutely limping child to age 5 years is discussed with attention in each clinical scenario to the role of radiography, ultrasound, nuclear medicine, computed tomography, and magnetic resonance imaging. Common causes of limping such as toddler's fracture, septic arthritis, transient synovitis, and osteomyelitis are discussed. 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 may supplement the available evidence to recommend imaging or treatment.

Pediatric Methicillin-Resistant Staphylococcus aureus Osteoarticular Infections

Osteoarticular infections (OSI) are a significant cause of hospitalizations and morbidity in young children. The pediatric patient with OSI presents unique challenges in diagnosis and management due to higher morbidity, effect on growth plate with associated long-lasting sequelae, and challenges in early identification and management. Methicillin-resistant Staphylococcus aureus (MRSA), first described in the 1960s, has evolved rapidly to emerge as a predominant cause of OSI in children, and therefore empiric treatment for OSI should include an antibiotic effective against MRSA. Characterizing MRSA strains can be done by antimicrobial susceptibility testing, detection of Panton–Valentine leukocidin (PVL) gene, staphylococcal cassette chromosome mec (SCCmec) typing, pulsed-field gel electrophoresis (PFGE), and multilocus sequence typing (MLST). Worldwide, community-onset methicillin-resistant staphylococcal disease is widespread and is mainly associated with a PVL-producing clone, ST8/USA300. Many studies have implied a correlation between PVL genes and more severe infection. We review MRSA OSI along with the pertinent aspects of its pathogenesis, clinical spectrum, diagnosis, and current guidelines for management.

Non-traumatic limping in Paediatric Emergencies: Epidemiology, evaluation and results

INTRODUCTION

Non-traumatic limping is a common reason for consultation in paediatric emergencies. Although transient synovitis of the hip (TS) is the most frequent diagnosis, there are cases of limping secondary to serious pathologies. The aim of this review is to describe the variables related to non-traumatic limp that come to the paediatric emergency department to establish the best management protocol, making the most of resources and speeding up emergency care.

MATERIAL AND METHOD

A prospective study was conducted, selecting all children less than 15 years old who consulted aspaediatric emergencies for non-traumatic limping during the 2014. Clinical variables, complementary examinations and diagnoses were collected in the emergency room consultation and 6 months after the consultation RESULTS: During 2014, 146 patients (0.69% of the emergencies) were included in the non-traumatic limping study. Four cases of severe limping were diagnosed: 2 leukaemias, 1 septic arthritis and 1 acetabular bone tumour. The most frequent diagnosis was TS (53.16%). At 6 months, 135 children (92.4%) had resolved lameness. The diagnosis was changed in 9 children (6.1%). Children with TS had fewer days of evolution, and 77% were between 3 and 10 years old. Children with a final diagnosis of severe pathology had a limp for longer, fever and did not weight bear on ambulation.

CONCLUSIONS

In limping of probable hip origin, at the ages of between 3 and 10, without fever or systemic symptoms and of less than one week's onset, it is possible to make a clinical diagnosis of TS limiting the use of complementary examinations.

Sonographic Evaluation of Fractures in Children

Fractures and suspected fractures are common causes for pediatric visits to the emergency department. Initial evaluation routinely includes imaging in the form of radiographs. Additional imaging modalities including sonography and magnetic resonance are used as problem-solving tools. Sonography has been reported to perform well when compared with radiography in multiple anatomies from the skull and nasal bones to the upper and lower extremities. In addition, sonography presents unique advantages including lack of ionizing radiation, cross-sectional coverage, evaluation of soft tissue injury, and the possibility of imaging the contralateral side. This article reviews the applications, advantages, disadvantages, technique, and performance of sonography in the imaging of fractures in children.

Bone and Joint Infections in Children: Septic Arthritis

The pathological invasion of a joint and subsequent inflammation is known as septic arthritis. The knee and hip are the most frequently involved joints. Staphylococcus aureus is the most common cause of septic arthritis in children. An acute onset of illness with an inflamed painful joint and restricted movements and inability to use joint (pseudoparalysis) clinically indicates septic arthritis. The diagnosis is difficult in a neonate or young child where refusal to feed, crying, discomfort during change of diaper (if hip is involved) or attempted joint movement may be the only findings. Fever and other systemic signs may also be absent in neonates. Septic arthritis is diagnosed clinically, supported by appropriate radiological and laboratory investigations. The peripheral blood white cell count is frequently raised with a predominance of polymorphonuclear cells. The acute phase reactants such as C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) are often markedly raised. Ultrasonography and MRI are preferred investigations in pediatric septic arthritis. Determination of infecting organism in septic arthritis is the key to the correct antibiotic choice, treatment duration and overall management. Joint aspirate and/or blood culture should be obtained before starting antibiotic treatment. Several effective antibiotic regimes are available for managing septic arthritis in children. Presence of large collections, thick pus, joint loculations and pus evacuating into surrounding soft tissues are main indications for surgical drainage. Joint aspiration can be a practical alternative in case the lesion is diagnosed early, with uncomplicated presentations and superficial joints.