Perthe’s Disease for the FRCSOrth

Courtesy: Sally Hobson, Hull Royal Infirmary, Hull, UK

Perthes Disease
Definition:

• Idiopathic osteonecrosis of capital femoral epiphysis in a growing child.

Epidemiology: –

• Males 4x females.
• 80% 4-9 (2-12 reported).
• Social class 4-5.
• Bilateral 10%:
• Usually asymmetric.

Presentation – history

• Limp.
• +/- hip/knee pain.
• Usually insidious/chronic onset.

Presentation – examination

• Reduced ROM – ABDUCTION.
• Ataxic/trendelenberg gait.
• Wasting thigh/buttock.
• FFD, limited rotation.
• LLD:
  o Adduction contracture.
  o True shortening due to collapse CFE.

Differential Diagnosis

• Acute presentation versus chronic post AVN hip xray.
• Unilateral versus bilateral.
  Infection.
  Inflammatory.
  Skeletal dysplasia (MED).
  Haematological:
  o Sickle cell/thalassaemia.
  o Haemophilia.
  o Leukaemia.
  Metabolic.
  Trauma.
  Iatrogenic (DDH

Investigations

• FBC/Inflammatory markers – exclude dd.
• X-ray diagnosis – only miss if very early presentation.
• Bone scan, MRI not usually required.
• Arthrogram / EUA can be useful.

Classification

• Catterall:
  % of head involvement 25/50/75/100.

Herrings lateral pillar classification:
o Comparison to contralateral, normal side.
o Based on the worst x-ray in the series.
A – lateral pillar preserved.
B ->50% maintained.
C – > 50 % involved

Aetiology

• Poorly understood.
• ?infection.
• ?trauma.
•  ?transient synovitis.
•  ?clotting abnormality
•  ?vascular changes primary or secondary to cartilage disorder.

Pathology – stages

• Early/infarction.
•  Intermediate/fragmentation.
• Healing.
• Remodelling.
• Whole disease process over several years.

Pathology – sclerotic

Infarction:
o Early – Hypertrophy of cartilage and reduced epiphyseal height.
o Later – Sclerosis, subchondral fracture (crescent sign).

Pathology – fragmentation

• Necrotic bone replaced by fibrocartilage.
• Revascularisation by creeping substitution.
• Areas of unossified cartilage stream across physis into metaphysis (cysts) – can cause growth arrest.

Pathology – healing

• Endochondral ossification – fibrocartilage reossifies.
• Last portion to form is anterosuperior epiphysis – round head becomes oval – can produce hinge abduction

Pathology – remodelling

Treatment – non-operative

• Bed rest.
• (Traction)
• Activity modification/crutches.
• Analgesia.
• Physio to maintain ROM.
  ? (Abduction brace).
• Herring says NONE of these affect outcome.
• Follow up patients 3-6 monthly depending on stage in disease and if considering surgery.

Treatment – operative

• Containment (in early/fragmentation phase):
• EUA arthrogram to assess.
  Options:
  o Proximal femoral osteotomy.
  o Salter osteotomy.
  o Shelf osteotomy.
  ?Hip distraction.

Outcomes

Herring says:
o A all do well regardless of treatment and age.
o C all do badly regardless of treatment and age.
o B – outcome improved by surgery IF patient over 8yrs.

• High rates of future OA/need for THR.
• Worse with higher Stulberg grade.

Treatment – salvage

• Valgus extension osteotomy.
• Chiari.
• Cheilectomy.
• Arthroplasty

Conclusion

• Aetiology unclear.
• Typical presentation but remember differential diagnoses.
• Predictable pathology.
• Treatment and assessment of outcome controversial:
  o EUA/arthrogram to plan.
  o Maintain ROM.
  o Containment.
  o Salvage surgery for painful hinge abduction.