A 3-year-old child presents with septic arthritis of the hip. Which is the most important reason to perform emergency surgical drainage rather than needle aspiration alone?

• A Needle aspiration cannot remove thick pus from the hip joint
• B Surgical drainage allows concurrent open synovectomy to prevent recurrence
• C General anaesthesia is required for adequate pain management during aspiration
• D The intracapsular pressure compresses the retinacular vessels, risking avascular necrosis of the femoral head if not rapidly decompressed ✓

Explanation

The femoral head in a child receives its blood supply almost exclusively via the retinacular vessels (branches of the medial femoral circumflex artery), which run in the hip capsule. Increased intracapsular pressure from purulent effusion compresses these delicate vessels, rapidly leading to avascular necrosis (osteonecrosis) of the femoral head — a devastating complication — within hours if untreated. Emergency arthrotomy and lavage decompress the joint and preserve the blood supply. Needle aspiration is inadequate for achieving sustained decompression.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.