Shawn, 12, attends his GP with four weeks of worsening left knee pain and an associated limp for the past week.

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<p>Shawn, 12, attends his GP with four weeks of worsening left knee pain and an associated limp for the past week.</p><p>There is no history of limb injury. He is systemically well, overweight, with no other medical history of note.</p><p>On examination he is afebrile. He has an antalgic gait, both knees and the right hip examine normally, but internal rotation of the left hip is limited to 10 degrees.</p><p>His GP requests hip imaging. Frog lateral pelvic X-ray view is shown.</p>

Dr Kate Kelso is medical co-editor at Australian Doctor and a GP in Sydney, NSW.