Investigating hip pain in a well child

A 9 year old girl with a history of conservatively managed left sided Perthes' (Legg-Calvé-Perthes) disease presented to her orthopaedic team via her general practitioner with onset of right hip pain and subsequent limp. She was otherwise well. On clinical examination she had a limp with moderate pain and some limitation of abduction and internal rotation. She did not have a fever, and routine haematology and biochemistry gave normal results. Assuming the disease can confidently be localised to the hip (rather than knee, pelvis, or lower back), a presumptive diagnosis of the painful hip is reasonable, based on age and presentation.