Avascular necrosis of the hip
Introduction
Avascular necrosis (AVN) may be defined as death of bone tissue secondary to loss of the blood supply. This leads to bone destruction and loss of joint function. It most commonly affects the epiphysis of long bones such as the femur.
Epidemiology
- Incidence: 2.50 cases per 100,000 person-years
- Peak incidence: 40-50 years
- Sex ratio: more common in males 4:1
| Condition | Relative incidence |
|---|---|
| Greater trochanteric pain syndrome | 120.00 |
| Acetabular labral tear | 20.00 |
| Osteomyelitis | 8.00 |
| Avascular necrosis of the hip | 1 |
| <1 | 1-5 | 6+ | 16+ | 30+ | 40+ | 50+ | 60+ | 70+ | 80+ |
Aetiology
Causes
- long-term steroid use
- chemotherapy
- alcohol excess
- trauma
Clinical features
Features
- initially asymptomatic
- pain in the affected joint
Investigations
Investigation
- plain x-ray findings may be normal initially. Osteopenia and microfractures may be seen early on. Collapse of the articular surface may result in the crescent sign
- MRI is the investigation of choice. It is more sensitive than radionuclide bone scanning
Management
Management
- joint replacement may be necessary