Pediatric Hip Pain

DDx

• Infectious (acute, localized, severe - refusal to bear weight, fever, elevated WBC, ESR, CRP)
  • Septic arthritis hip or sacroiliac joint
  • Osteomyelitis of femoral head or pelvis
  • Lyme disease
  • Referred
    • Psoas/abdominal/pelvic abscess
    • Appendicitis
    • Discitis
• Inflammatory (chronic, insidious except synovitis may be acute)
  • Systemic arthritis
• Orthopedic (hip pain may be referred to thigh/knee, acute or insidious, worse pain on activity, decrease at rest, no systemic symptoms, ESR/CRP normal)
  • Slipped capital femoral epiphysis (SCFE)
  • Legg-Calvé-Perthes disease (LCP) / Avascular necrosis
• Neoplastic (night-time pain, unrelated to activity, systemic symptoms, anemia, leukopenia, thrombocytopenia, high LDH or uric acid)

History

• Onset
  • Acute
    • Infectious
    • Transient synovitis
    • Trauma
  • Insidious
    • Slipped capital femoral epiphysis (SCFE)
    • Legg-Calvé-Perthes disease (LCP)
    • Juvenile idiopathic arthritis (JIA)
• Systemic symptoms (fever, weight loss, fatigue, GI symptoms)
• Trauma
• Other joints involved - JIA
• Previous similar episodes in same or contralateral hip - JIA or transient synovitis (15% recurrence)
• Recent URTI - transient synovitis (but nonspecific)
• Recent antibiotics - alter presentation of infection
• Family history
  • Inflammatory arthritis, psoriasis, inflammatory bowel disease, or uveitis - JIA

Physical Exam

• Vitals
• Gait
• Ability to bear weight – r/o severe hip/pelvis/spine pathology
• Hip exam
  • Observation - Asymmetry
  • Palpation
  • ROM - supine and prone (ensure to stabilize pelvis)
    • FABERE test for sacroiliac arthritis r/o septic
• Spine/knee exam

Investigations

• CBC, ESR, CRP
• Blood Culture
  • If febrile and suspect osteomyelitis or septic arthritis
• Lyme serology, Borrelia burgdorferi IgG Ab
  • If residence in or travel to Lyme endemic region
• Hip X-ray (anteroposterior and frog-leg views)
  • r/o trauma, malignancy, advanced (not early) LCP, JIA, SCFE
• Hip Ultrasounds
  • r/o effusion (bilateral suggestive of transient synovitis, unilateral r/o septic arthritis consider joint aspirate)
• MRI
  • r/o osteomyelitis, early LCP, and early SCFE

Rule out septic arthritis

• Kocher Criteria
  • Non-weight-bearing on the affected side
  • ESR > 40 mm/hr
  • Fever
  • WBC count > 12,000
• If low pre-test probability
  • Negative ultrasound for hip effusion -> Outpatient follow-up
• If moderate pre-test probability
  • Negative U/S
    • If <24h, Repeat U/S in 12h or MRI
    • If >24h, Outpatient follow-up
  • If positive ultrasound -> Arthrocentesis for synovial fluid analysis