What are the key clinical features to consider when diagnosing Perthes disease in children?

When considering Perthes disease in children, it is identified as a key diagnosis that demands early intervention and treatment among children presenting with a limp ¹,²,³. The condition is also known as Legg-Calvé-Perthes syndrome or disease (Catterall, 1981; Wall, 1999). While the provided guidelines do not detail specific clinical features unique to Perthes disease, they emphasise the importance of specialist assessment for a child with a limp if there is uncertainty about the cause, if the cause cannot be managed in primary care, or if the child presents with a limp on multiple different occasions ¹,²,³.

It is important to differentiate Perthes disease from other conditions. For instance, transient synovitis is typically considered in well, afebrile, mobile but limping children aged 3–9 years ³. Children outside this age range or those with red flag symptoms (such as fever, pain waking the child at night, redness, swelling, stiffness, weight loss, or inability to bear weight) require urgent specialist assessment to exclude more serious pathologies like infection or malignancy ¹,²,³. If a child has a persistent limp with a normal initial X-ray, referral to paediatric orthopaedics or rheumatology for further investigation is indicated ³.