What is the initial approach for a 2-year-old presenting with a right leg limp, no history of trauma, and no apparent pain?

Initial Approach to a 2-Year-Old with Painless Right Leg Limp

Begin with limited tibia/fibula radiographs of the right leg as the initial imaging study, since spiral tibial fractures ("toddler's fractures") are by far the most common cause of nonlocalized limp in children under 4 years of age, even without a clear history of trauma. 1

Immediate Clinical Assessment

Rule out infection first, even though the child appears comfortable:

• Check temperature - fever >101.3°F (38.5°C) combined with refusal to bear weight strongly suggests septic arthritis, a true orthopedic emergency requiring intervention within hours 2, 3, 4
• Assess inflammatory markers (CBC, ESR, CRP) if any concern for infection exists - elevated values necessitate urgent hip ultrasound and possible joint aspiration 2, 3
• Observe for systemic toxicity - lethargy, irritability, or poor feeding indicate serious infection requiring urgent evaluation 2

Physical Examination Priorities

Systematically examine from hip to foot since 2-year-olds typically cannot verbalize or localize symptoms accurately 1:

• Hip examination is critical - hip pathology can refer pain to the thigh, knee, or buttock in up to 30% of cases, leading to misdiagnosis 1, 5, 3
• Palpate the entire lower extremity for focal tenderness, swelling, or erythema 1
• Assess weight-bearing ability - complete refusal to bear weight raises concern for fracture or septic arthritis 2, 4
• Check for leg-length discrepancy using the Galeazzi sign 1

Initial Imaging Strategy

For a 2-year-old with nonlocalized symptoms and no fever:

• Start with tibia/fibula radiographs (AP and lateral views) rather than full lower extremity films, as spiral tibial fractures account for the vast majority of fractures in this age group presenting with limp 1
• Radiographs are often initially normal - approximately 10% of tibial fractures only become visible on follow-up radiographs obtained 7-10 days later 1, 5, 3
• Consider hip ultrasound if initial radiographs are negative and symptoms persist, since hip pathology frequently presents with referred pain elsewhere 1, 5

Management Based on Initial Findings

If radiographs are normal with improving symptoms:

• Provide observation and reassurance with follow-up in 1-2 weeks if symptoms persist 2, 3
• Prescribe short-course NSAIDs for analgesia 2, 3
• Counsel parents that transient synovitis accounts for 80-85% of atraumatic limps in young children and is self-limiting 6

If radiographs are normal but symptoms persist or worsen:

• Repeat clinical examination and obtain follow-up radiographs in 7-10 days 1, 2, 3
• Consider hip ultrasound to evaluate for joint effusion, even without fever 1, 5
• Obtain MRI of the lower extremity if symptoms worsen or red flags develop (fever, inability to bear weight, systemic symptoms) 1, 2

Critical Pitfalls to Avoid

Never assume normal initial radiographs exclude fracture - toddler's fractures are notoriously difficult to visualize initially and may only appear on follow-up imaging 1, 5, 3

Do not focus solely on the leg - always examine the hip thoroughly, as hip pathology is a common cause of lower extremity limp in this age group 1, 5, 3

Maintain high suspicion for serious pathology - one case series reported a child initially discharged with negative imaging who returned with spinal discitis and epidural abscess 1

Ensure close follow-up - if symptoms persist beyond 1-2 weeks despite normal initial workup, reassess and consider advanced imaging or specialist referral 2, 3