- Occurs most commonly in the 20–50 age group.
- Bilateral: 50% of idiopathic cases, or 80% in steroid-induced cases.
- Commonly seen following intracapsular fractures of the femoral neck. Increased risk if displaced (up to 80%).
- Risk factors: steroid use, alcohol abuse, metabolic disease (e.g. Gaucher’s disease), vasculitis (SLE), sickle cell disease, occupational causes (e.g. deep sea divers – caisson disease), venous thromboembolism and bone-marrow transplant.
- Classically present with pain of insidious onset.
- Pain often worse at night.
- Pain is usually severe but may become more bearable after several weeks.
- The initial radiograph if taken early may be normal.
- The affected bone becomes sclerotic with later collapse and remodelling.
- Ficat staging (1968 Ficat and Arlet).
- 0 – pre-clinical – not included in original classification – normal X-ray and MRI.
- 1 – pre-radiological – pain, normal X-ray, early MR changes.
- 2 – sclerosis on X-ray but congruent head.
- 3 – flattened head with crescent sign.
- 4 – secondary degenerative changes.
- Remove any causative factors.
- Management is targeted towards preservation/restoration of vascularity where possible, or reconstruction in late disease.
- Techniques used in each disease stage include:
- 1 – core decompression.
- 2 – core decompression and strut graft (free or vascularised).
- 3 – strut graft/total hip replacement.
- 4 – total hip replacement.
James R. D. M., Erskine J. H., Rakesh R. M. (2008). Musculoskeletal Radiology. A-Z Musculoskeletal and Trauma Radiology, 1st edition, Cambridge University Press, Cambridge, 1, 1-176.