Approach to a Child with a Limp

Initial Assessment and Diagnosis

The American College of Radiology recommends beginning with a focused assessment to identify fever, localize symptoms, and determine if infection is present, as these factors drive the diagnostic algorithm and imaging strategy 1, 2
Fever >101.3°F (38.5°C) combined with refusal to bear weight strongly suggests septic arthritis, which requires diagnosis and intervention within hours to prevent permanent joint damage 3, 4
The American Academy of Pediatrics suggests that systemic toxicity, such as lethargy, irritability, or poor feeding, indicates serious infection requiring urgent evaluation 3
Inability to bear weight or refusal to move a joint is highly concerning for septic arthritis, an orthopedic emergency 3

The American College of Radiology recommends obtaining hip ultrasound immediately to assess for joint effusion if symptoms are localized to the hip 5, 6, 4
If symptoms are localized to the lower extremity (not hip), obtain MRI of the area of interest without and with IV contrast as the initial imaging modality 6
For nonlocalized symptoms, obtain MRI of the entire lower extremity without and with IV contrast to localize the source of infection 6

The American Academy of Pediatrics suggests providing observation and reassurance if radiographs are normal with improving symptoms, and prescribing short-course NSAIDs for analgesia 4, 7
If normal radiographs with persistent or worsening symptoms, repeat clinical examination, obtain follow-up radiographs in 7-10 days, and consider advanced imaging (MRI or ultrasound) if symptoms worsen or red flags develop 2, 4, 8
Immediate emergency department referral is recommended for fever with inability to bear weight or move the joint, or suspected septic arthritis or osteomyelitis 3

The European Society of Paediatric and Neonatal Intensive Care recommends that hip POCUS is operator-dependent and requires adequate training, with specific competency standards before independent use 9, 10

The combination of clinical predictors, such as fever, refusal to bear weight, and elevated inflammatory markers, with hip ultrasound provides a powerful risk stratification tool to identify children requiring urgent intervention for septic arthritis, although the exact criteria are not specified in the provided citations 9, 10

Approximately 10-41% of occult fractures, particularly toddler's fractures, only become visible on follow-up radiographs obtained 7-10 days later, highlighting the importance of repeat imaging in the management of afebrile, non-weight-bearing children with normal initial radiographs, as recommended by the American College of Radiology 11
MRI is highly sensitive for detecting stress fractures, occult fractures, bone marrow pathology, and early inflammatory changes that radiographs miss, and should be considered if symptoms persist or worsen despite normal initial and follow-up radiographs, according to the American College of Radiology 11, 12

The American College of Radiology recommends that MRI be reserved for specific scenarios, such as persistent or worsening symptoms despite normal initial and follow-up radiographs, and not for routine use 11, 12
Approximately 10-41% of tibial fractures appear only on follow-up films, emphasizing the need for careful evaluation and follow-up imaging in children with minor trauma and normal initial radiographs, as noted by the American College of Radiology 11

Septic arthritis can cause permanent joint damage within hours if left untreated, highlighting the importance of prompt evaluation and treatment if fever develops in a child with minor trauma and normal initial radiographs, as emphasized by the American College of Radiology 12