Risk factors
- Previous hip trauma — fracture or dislocation
- High-dose or long-term oral corticosteroids
- Heavy alcohol consumption
- Decompression injuries (deep-sea diving)
- Sickle cell disease
- Chemotherapy and radiotherapy
- Idiopathic — no identifiable cause in many cases
Symptoms
Pain typically develops in the groin or buttock and progresses over weeks to months. Pain is often worse with weight-bearing and may eventually persist at rest. Once the femoral head collapses, the joint becomes mechanically symptomatic with stiffness, limp and rapid arthritic change.
Diagnosis
- X-ray — may be normal in early disease. Later shows sclerosis, crescent sign (subchondral fracture) and eventual collapse of the femoral head.
- MRI — the most sensitive investigation; required for diagnosis when X-rays are normal.
Treatment
Core decompression
For early disease before collapse, core decompression drills one or more channels into the affected area of the femoral head to reduce intra-osseous pressure and stimulate revascularisation. Reported success in preventing progression ranges from 50–80% when performed early.
Hip replacement
Once collapse has occurred or arthritic change is established, total hip replacement reliably restores function and relieves pain.