Perthes disease

How to Treat article “ A GP guide to paediatric orthopaedics” Dec 2019; Orthobullets; RCH ortho fact sheet

= idiopathic avascular necrosis of epiphysis of the femoral head

• 

• Over months to years, the femoral head undergoes necrosis, fragmentation, collapse of comprised epiphysis & eventual healing & remodeling
• Diagnosis of exclusion

Epidemiology

• affects 1 in 10,000 children
• Age distribution 3-12yrs
• peak from 5-7yrs – Presentation is typically at a younger age than slipped upper femoral epiphysis (SUFE) with peak presentation at 5-6 years,
• More common in males
• Bilateral disease is common – 12%, but not usually concurrently
• race – Caucasian > East Asian and African American

• Risk factors
  • positive family history
  • low birth weight
  • abnormal birth presentation
  • second hand smoke
  • Asian, Inuit, and Central European decent

4 Stages of disease

Stage	Appearance
1. Sclerosis	Femoral head appears dense & smallerMedial joint space widening
2. Fragmentation	Subchondral lucencyMottled appearance & irregularity of femoral head
3. Re-ossification	Healing begins & the femoral head appears more defined
4. Healing	Complete collapse & flattening of the femoral head, widening of the femoral neck

DDx

1. Infection – septic arthritis, OM
2. Transient synovitis
3. Multiple epiphyseal dysplasia
4. Sickle cell disease
5. Hypothyroidism

History

1. Limp including painless limp
2. Atraumatic intermittent ache in hip, thich or knee 
3. Insidious onset

Examination

1. Restricted internal rotation & abduction of hip
2. Limb length discrepancy
3. hip stiffness
4. gait disturbance
   • antalgic limp
   • Trendelenburg gait (head collapse leads to decreased tension of abductors)
5. limb length discrepancy
   • late finding
   • hip adduction contracture can exacerbate the apparent LLD

Investigations

1. XR (AP & frog legs)– may be NAD in early stages. Typical findings of “crescent sign” in fragmentation phase.
2. MRI or bone scan – ↓ signal in hypoperfused femoral head

Treatment

• NSAIDs, traction, crutches
• Non-Weight Bearing Strategies:
  • Restriction of Activities: Children may be advised to avoid weight-bearing activities to reduce stress on the femoral head and minimize deformation.
  • Crutches or Wheelchairs: To facilitate non-weight-bearing mobility and reduce hip load.
  • Casting or Bracing (Petrie Casts): Bracing with abduction casts or orthoses can help keep the femoral head well-centered within the hip socket.
• Physical Therapy:
  • Focuses on maintaining range of motion, strengthening surrounding muscles, and improving joint flexibility.
  • Stretching exercises, particularly for the hip abductors and adductors, to minimize stiffness.
  • Low-impact activities such as swimming can help maintain joint mobility without putting excess stress on the hip.
• Surgical Management
  • Surgery may be indicated for children over 6 years old with severe disease, significant femoral head deformity, or in cases where conservative measures are not effective.
  • Osteotomy:
    • Femoral Osteotomy: Involves cutting and repositioning the femur to improve the alignment of the femoral head with the acetabulum.
    • Pelvic Osteotomy (e.g., Salter or Chiari): Reshapes or reorients the pelvic bone to enhance the acetabular coverage of the femoral head.
  • Shelf Acetabuloplasty:
    • A procedure to extend the bony roof of the acetabulum to better contain and support the femoral head.
  • Arthrodiastasis (Joint Distraction):
    • Use of an external fixator to relieve pressure on the femoral head and promote healing.
• observation alone
  • activity restriction (non-weightbearing), and physical therapy (ROM exercises)
    • children < 8 years of age (bone age <6 years)
    • young patients typically do not benefit from surgery

Prognosis

• Age-Related Outcomes: Younger children (typically under 6 years) often have a better prognosis due to their greater bone remodeling capacity, while older children may face more challenges.
• Disease Stages: The prognosis depends on the stage and severity of disease involvement.
  • Children with less femoral head deformation have a better long-term outcome.
    • sphericity of femoral head and congruency at skeletal maturity (Stulberg classification)
• Variables of poor prognosis
  • female sex
  • decreased hip abduction (adduction contracture)
  • heavy patient
  • longer duration from onset to completion of healing
  • stiffness with progressive loss of ROM

Natural history

• long-term studies suggest that most patients do well until fifth or sixth decade of life
• approximately 1/2 of patients develop premature osteoarthritis secondary to an aspherical femoral head
• Self-limiting process
• variable course to final healing from initial ischemic event
• can take 2-5 years to resolve