The pelvic x-ray shows increased density of the femoral heads, which is consistent with avascular necrosis. In this case, no obvious cause was found.

The mnemonic VINDICATE summarises the causes of avascular necrosis of the femoral head:

• V – vascular causes (e.g. sickle cell disorder)
• IN – infection (e.g. septic emboli)
• D – drugs (e.g. steroids, alcohol)
• I – inflammation (e.g. pancreatitis); idiopathic
• C – congenital (e.g. Gaucher’s disease)
• A – autoimmune (e.g. SLA, rheumatoid arthritis)
• T – trauma (e.g. fracture neck of femur, dysbarism)
• E – endocrine causes (e.g. Cushing’s disease)