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