What causes avascular necrosis of the hip?

The femoral head is the rounded top of the thigh bone that fits into the hip socket. It depends on small blood vessels for oxygen and nourishment. When that supply is interrupted, bone tissue can weaken and gradually lose its normal shape. A hip fracture or dislocation can injure vessels around the joint; [Hip Fracture](/conditions/hip-fracture/) is one recognised cause. Some people develop avascular necrosis without a single obvious injury, so the absence of trauma does not rule it out. Early symptoms may be subtle, then progress to deep groin or buttock pain, reduced hip movement, and difficulty walking.

Arrange an orthopaedic assessment if persistent groin or hip pain is limiting walking, stairs, or sleep, particularly after a hip injury. Keep a record of when pain occurs and avoid forcing painful weight-bearing activity. The clinician may assess gait and hip movement and choose imaging based on the stage and suspected cause. Treatment decisions depend on bone changes, symptoms, age, activity needs, and the condition of the joint.

Seek urgent care after a fall or impact that causes severe hip pain, inability to stand, leg shortening, or an unusual leg position. For known or suspected avascular necrosis, prompt review is sensible when pain worsens, walking becomes harder, or hip movement declines.

Could reduced blood flow explain my hip symptoms? Was there an injury that may have affected the joint vessels? Which scan is appropriate? How should I protect the hip while we clarify the diagnosis?