Synopsis
Recognise childhood femoral-head osteonecrosis, preserve hip motion and containment during biological fragmentation and select reconstruction by age, head involvement and mechanical congruence.
- Perthes disease is idiopathic osteonecrosis of the capital femoral epiphysis, classically presenting between four and eight years with limp and hip, thigh or knee pain.
- High-yield examination shows reduced hip abduction and internal rotation, an antalgic or Trendelenburg gait and possible thigh wasting.
- First-line imaging is bilateral AP pelvis and frog-leg lateral radiography; obtain MRI when early disease remains suspected despite normal films.
- Waldenström evolution moves through initial necrosis, fragmentation, reossification and healed remodelling over several years.
- Lateral-pillar height during fragmentation, age at onset, range and femoral-head containment are central prognostic variables.
- First-line treatment in a younger child with maintained containment is education, temporary impact reduction, analgesia and active restoration of abduction and rotation.
- Use protected loading for painful fragmentation, but avoid prolonged indiscriminate immobilisation that worsens stiffness and deconditioning.
- Older age, substantial lateral-pillar collapse or extrusion may justify femoral or pelvic containment surgery before fixed hinge abduction develops.
Key red flags
Fever, severe rest pain, systemic illness or marked inflammatory response is not typical Perthes disease and requires emergency infection assessment.
An older or obese adolescent with obligatory external rotation has possible SUFE rather than Perthes and must be made non-weight-bearing immediately.
Progressive loss of abduction or internal rotation allows extrusion and deformation and should prompt earlier specialist reassessment.
A head that hinges rather than enters the acetabulum during abduction should not be forced into containment treatment.
Bilateral symmetrical epiphyseal change or disproportionate short stature suggests skeletal dysplasia, endocrine disease or another systemic disorder.
Persistent limp after presumed transient synovitis needs repeat examination and imaging because early Perthes radiographs can initially appear normal.
Investigation priorities
Identify epiphyseal density, collapse, extrusion, acetabular coverage and bilateral or alternative disease.
Management branches
A young child has ongoing limp, referred knee pain or loss of abduction and internal rotation.
- Assess fever, systemic state, weight-bearing ability and red flags before performing gentle bilateral hip examination.
- Obtain AP pelvis and safe frog-leg lateral views of both hips and review previous transient-synovitis episodes.
- Use MRI when radiographs are normal but compatible restriction or limp persists.
- Refer confirmed or strongly suspected disease to paediatric orthopaedics for stage and containment assessment.