Osteochondritides: Perthe’s Disease Flashcards
Define Perthe’s Disease.
Idiopathic avascular necrosis of the capital femoral epiphysis of the femoral head.
What is the aetiology of Perthe’s Disease?
Unknown aetiology; probably multifactorial. 25% bilateral (doesn’t occur synchronously in each hip). Possible theories: altered growth patterns (short stature, decreased growth factors and delayed bone age), trauma (absent activity association, however), thrombosis, and fibrinolysis defects (sickle cell disease and crisis, protein C and S deficiency).
What are risk factors for Perthe’s Disease?
Sickle cell disease
Socio-economic deprivation
Low birthweight
Increased parental age
Later-born children
Passive smoking
What is the pathophysiology of Perthe’s Disease?
- Femoral epiphysis rapid growth
- Vascular supply interruption
- Ischaemia
- Subchondral cortical bone infarction and avascular necrosis
- Eventual bone ossification with revascularisation. Remodelling at this stage determines prognosis. Articular cartilage is unaffected as synovial fluid provides nutrients.
What are the classifications of Perthe’s Disease?
Modified Elizabethtown Classification:
- I: Sclerotic (A = no loss of height, B= height loss)
- II: Fragmentation (A = early, B= late)
- III: Healing (A= peripheral, B > 1/3 epiphysis)
- IV: Healed.
Summarise the epidemiology of Perthe’s Disease,
6-12/100,000
Peak: 7 years
M:F = 6:1
What are presenting symptoms for Perthe’s Disease?
Limp: Early sign, intermittent, abductor lurch, post-exercise. Classic presentation is with a painless limp.
Pain: Classically painless although may have mild intermitted pain in anterior thigh or hip pain secondary to necrosis of affected bone, possibly referred to the medial aspect of the ipsilateral knee/lateral thigh.
What are signs of Perthe’s Disease?
Look: Atrophy of the quadriceps muscles secondary to disuse on the affected side, leg length inequality, hip adduction flexsion deformity, antalgic or Trendelenburg gait (secondary to gluteus medius pain).
Feel: Nil objective signs (hidden point).
Move: Restricted ROM, particularly rotation and abduction (secondary impingement lesions). Late stages are characterised by global decrease in all ROM.
Roll test: Supine position; roll the foot of the affected hip into internal and external rotation +ve test invokes guarding or spasm, especially with internal rotation.
Clinical femoral head ‘at-risk’ signs (catterall): Increased age, increased weight, progressive loss of movement, adduction contracture, flexion with adduction.
What are appropriate investigations for Perthe’s Disease?
Bloods: FBC, CRP/ESR (?septic arthritis), Hb electrophoresis (? Sickle cell)
Joint aspiration: Exclude septic arthritis
X-ray (AP and frog-leg): Catterall head ‘at-risk’ signs; Gage sign, calcification lateral to the epiphysis, subluxation, epiphyseal angle, diffuse metaphyseal reaction.
Imaging: Bone scan, arthrography, MRI
What is the general management for Perthe’s Disease based on?
Based on Catterall clinical/radiological grade and Elizabethtown stage
What is the containment theory of Perthe’s Disease?
Secure the injured femoral head within the socket and movement continued, thus postregeneration is round and fully mobile.
When is conservative treatment suitable for Perthe’s Disease?
Only with healing stage (>8 years old), or if clinically good (< 7 years old).
Explain the surgical management of Perthe’s Disease.
To achieve containment and salvage the joint.
Includes proximal femoral osteotomies, acetabular surgery, abduction osteotomies and cheilectomy. Avoidance of extensive and prolonged immobilisation.
What are complications associated with Perthe’s Disease?
Permanent femoral head deformity and early osteo-arthritis.
What is the prognosis of Perthe’s Disease?
Iowa long-term follow-up (40 years): 40% had a joint replacement, 10% disabling arthritis requiring a replacement, 10% had Iowa hip score <80.
