What is the approach to a child presenting with a limp?

Approach to a Child with a Limp

Begin with a focused assessment to identify fever, localize symptoms, and determine if infection is present—these three factors drive the entire diagnostic algorithm and imaging strategy. 1

Initial Clinical Assessment Framework

Critical Red Flags Requiring Emergency Evaluation

• 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 2, 3, 4
• The "three As"—anxiety, agitation, and high analgesic requirement—indicate serious pathology such as compartment syndrome or severe infection when verbal communication is limited 3, 5
• Systemic toxicity (lethargy, irritability, poor feeding) indicates serious infection requiring urgent evaluation 2
• Inability to bear weight or refusal to move a joint is highly concerning for septic arthritis, an orthopedic emergency 2

Essential History Elements

• Timing and pattern of pain: acute onset (<48 hours) versus chronic (>2 weeks) 3, 4
• Trauma history: even minor falls can cause occult fractures in young children 2, 3
• Associated symptoms: fever, night pain, morning stiffness >30 minutes (suggests inflammatory arthritis), systemic symptoms 2, 6
• Pain localization: recognize that young children mislocalize pain—hip pathology presents as thigh or knee pain in up to 30% of cases 3, 6

Physical Examination Priorities

• Observe gait pattern if the child is ambulatory to help localize pathology 1, 3
• Palpate systematically along the entire lower extremity for swelling, erythema, deformity, and focal tenderness 3, 6
• Examine the joint above and below the area of complaint—never focus only on the reported pain site 5
• Assess for joint effusion and range of motion limitations 4
• Perform neurological assessment including deep tendon reflexes and muscle tone 3, 6

Diagnostic Algorithm Based on Clinical Presentation

Scenario 1: Fever Present + Concern for Infection

If symptoms are localized to the hip:

• Obtain hip ultrasound immediately to assess for joint effusion—this is the most critical first step 1, 3
• Order laboratory tests: CBC, ESR, CRP, and blood cultures 2, 3, 4
• If effusion is present, perform ultrasound-guided arthrocentesis for synovial fluid analysis (cell count with differential, Gram stain, culture, crystal analysis) 2, 3
• Synovial fluid WBC >50,000 with >75% neutrophils strongly suggests septic arthritis 2
• Kocher criteria increase diagnostic probability: temperature >38.5°C, WBC >12,000/mm³, ESR >40 mm/hr, inability to bear weight 4, 5
• Consider MRI pelvis without and with IV contrast if ultrasound is negative but clinical suspicion remains high 1

If symptoms are localized to lower extremity (not hip):

• Obtain MRI of the area of interest without and with IV contrast as the initial imaging modality 1
• Order laboratory tests: CBC, ESR, CRP, blood cultures 3, 4
• MRI is highly sensitive for osteomyelitis, soft-tissue infections, and bone marrow pathology 1

If symptoms are nonlocalized:

• Obtain MRI of the entire lower extremity without and with IV contrast to localize the source of infection 1
• Order laboratory tests: CBC, ESR, CRP, blood cultures 3, 4
• Whole-body MRI may be considered if multifocal osteomyelitis is suspected 1

Scenario 2: No Fever + No Concern for Infection + Symptoms Localized

Obtain plain radiographs (anteroposterior and lateral views) of the specific area of concern as the initial imaging modality 1, 4

• Radiographs are the first-line imaging for joint pain in children and can diagnose fractures, osteochondritis, apophysitis, osteonecrosis, or tumors 1, 2
• If initial radiographs are normal but symptoms persist, obtain follow-up radiographs in 7-10 days—approximately 10% of tibial fractures appear only on follow-up films 1, 3
• Consider MRI if radiographs remain negative and symptoms persist or worsen, as MRI is highly sensitive for stress fractures, soft-tissue pathology, and early bone marrow changes 1

Scenario 3: No Fever + No Concern for Infection + Symptoms Nonlocalized

In children <4 years of age who cannot verbalize or localize symptoms, obtain limited tibial/fibula radiographs bilaterally as the initial imaging 1, 3

• Spiral tibial fractures (toddler's fractures) are by far the most common fractures in children <4 years presenting with nonlocalized limp or refusal to bear weight 1
• Avoid ordering radiographs from pelvis through feet initially—this approach exposes the child to unnecessary radiation when tibial/fibular fractures are most common 1
• If initial tibial/fibular radiographs are normal and symptoms persist, consider:
  • Follow-up radiographs in 7-10 days (10% of toddler's fractures only visible on follow-up) 1
  • Radiographs of other areas (hip, femur, ankle, foot) based on repeat clinical examination 1
  • Hip ultrasound if hip pathology is suspected (hip pain can refer to thigh, knee, or buttock) 1
  • MRI lower extremity if symptoms worsen or red flags develop 1

Age-Specific Differential Diagnoses

Children 1-2 Years Old

• Osteoarticular infection (septic arthritis, osteomyelitis) is the main concern in terms of frequency and potential seriousness 7
• Fractures (especially toddler's fracture) are also common 1, 7

Children 3-8 Years Old

• Osteoarticular infection should be sought as a priority 7
• Transient synovitis is the most common cause of hip pain in this age group and is self-limited 2, 4
• Legg-Calvé-Perthes disease (avascular necrosis of femoral head) typically occurs in children aged 4-8 years 2
• Diagnosis of transient synovitis should only be made after excluding other conditions including infection, benign bone tumors (osteoid osteoma), malignant tumors, inflammatory monoarthritis, trauma with or without fracture, apophysitis, and leukemia 7
• Question the diagnosis of transient synovitis if symptoms persist >7 days 7

Children >9 Years Old

• Slipped capital femoral epiphysis (SCFE) is the diagnosis not to miss, as it can have serious implications for future hip function 7
• All other diagnoses from younger age groups remain possibilities 7

Management Based on Initial Findings

If Normal Radiographs with Improving Symptoms

• Provide observation and reassurance 3, 6
• Prescribe short-course NSAIDs for analgesia 3, 6
• Schedule follow-up in 1-2 weeks if symptoms persist 3, 6

If Normal Radiographs with Persistent or Worsening Symptoms

• Repeat clinical examination to reassess for new findings 1, 3
• Obtain follow-up radiographs in 7-10 days to detect occult fractures that become visible over time 1, 3
• Consider advanced imaging (MRI or ultrasound) if symptoms worsen or red flags develop 1, 3
• Reassess for infection if fever or systemic symptoms develop 1, 3

Critical Pitfalls to Avoid

• Never assume normal radiographs exclude fracture—10% of tibial fractures only appear on follow-up films 1, 3, 6
• Never focus only on the reported pain site—young children frequently mislocalize pain, and hip pathology presents as knee or thigh pain in up to 30% of cases 3, 6
• Never delay evaluation of fever with inability to bear weight—septic arthritis causes permanent joint damage within hours if not treated urgently 2, 3, 6
• Never ignore the "three As" (anxiety, agitation, high analgesic requirements)—these suggest serious pathology such as compartment syndrome or severe infection 3, 5
• Never diagnose transient synovitis without excluding infection first—septic arthritis is an orthopedic emergency 2, 7
• Never consider psychogenic etiology, tendinitis, or sprain in young children—these diagnoses risk delaying identification of potentially serious conditions 7

Referral Guidelines

Immediate Emergency Department Referral

• Fever with inability to bear weight or move the joint 2
• Suspected septic arthritis or osteomyelitis 2
• Vascular compromise, compartment syndrome, or open fractures 5

Urgent Orthopedic Referral

• Confirmed fractures requiring surgical intervention 4
• Suspected SCFE or Legg-Calvé-Perthes disease 2, 7

Urgent Rheumatology Referral

• Arthritis involving one or more joints 2
• Persistent joint pain or swelling >2 weeks without clear diagnosis 2
• Morning stiffness >30 minutes suggesting inflammatory arthritis 2