Synopsis
Recognise osteonecrosis before articular collapse, stage mechanical integrity with appropriate imaging and refer early enough for joint-preserving treatment while managing causative exposures safely.
- Suspect femoral-head osteonecrosis with progressive groin, buttock or referred knee pain and painful internal rotation, particularly after steroids, alcohol, trauma, sickle-cell disease or transplantation.
- First-line imaging is anteroposterior pelvis plus lateral views of the symptomatic hip; normal radiographs do not exclude early disease.
- MRI without contrast is the reference confirmatory and staging test when suspicion persists, defining lesion size, location, bilaterality and subchondral integrity.
Key red flags
A native hip dislocation is time-critical: perform trauma assessment, document sciatic and vascular function and arrange urgent reduction under the appropriate specialist pathway.
Investigation priorities
Assess shape, sclerosis, crescent fracture, collapse, arthritis and an alternative lesion while comparing both hips.
Management branches
Hip dislocation or displaced femoral-neck fracture creates immediate vascular risk.
- Use trauma ABCDE and document distal vascular and sciatic-nerve function before and after intervention.
- Arrange urgent reduction or fracture surgery through the specialist pathway rather than waiting for elective MRI.
Key medicines
Paracetamol for symptomatic bridgeTake 500 to 1,000 mg orally when needed, leaving at least four hours between doses and limiting total intake to 4 g per day, with a lower maximum for low weight or hepatic risk.
Topical diclofenac for accessible referred painApply 2 to 4 g of diclofenac 1.16% gel to intact painful lateral hip or knee skin per dose, within the licensed maximum of three or four daily applications for a short trial.