Limp is a symptom and not a diagnosis. The differential diagnosis will change according to the child’s age.

A febrile child with a limp, or a non-weight bearing child, needs same day assessment. Red flag features include high fever, weight loss, night pain, lethargy or a new cardiac murmur. Ask about history of recurrent fevers even if the patient has no current fever as the presence of recurrent fevers can indicate the presence of sub-acute or chronic brucellosis.

A limp persisting beyond two weeks requires referral to paediatrics, paediatric rheumatology or paediatric orthopaedics.

Consider a history of trauma, including non-accidental injury, but be aware that children with pathology may be more prone to falling.

Ask about morning stiffness, 'gelling after rest' and any observation of joint swelling. Consider inflammatory causes such as Juvenile Idiopathic Arthritis (even if the blood tests and radiographs are normal).

Be familiar with “normal” motor milestones. If motor development is delayed then consider arranging a CK test early.

Many hip pathologies cause limp, but remember to assess other joints and think of extra-articular causes (including footwear and soles of feet for minor trauma or infection).

Growing pains should never cause a limp. Do not ascribe limp to 'growing pains'.

History and examination will give you the likely differential diagnosis, but investigations may be helpful to exclude pathology. What investigations to do is influenced by the clinical context.

pGALS is a useful and quick tool to assess all joints and guide further detailed examination.