Case of the month: Can you spot the underlying cause for this child’s limp?

In the next in our series, Dr David Capehorn asks what the likely diagnosis is in this case of a child presenting repeatedly with a limp. Put your suggestions in the comments section below. Answer to be revealed soon!

Note that details of the case have been altered to protect individuals’ identities    

A four-year-old boy initially presents to clinic with a limp. His mother explains that it had started ‘the morning after a trampoline party,’ and that she ‘thought it was just a twist from falling’. She had taken him the following day to the local Minor Injuries Unit. An X-ray of his lower leg and ankle showed no fracture. The report reads: Diagnosis: Minor soft tissue injury. Reassure, advise rest and paracetamol

The child has mild developmental delay – he’s chatty, but clearly behind in speech. He walks with a subtle limp, but doesn’t appear to be in pain. On examination, there’s no swelling or bruising. Hip, knee and ankle all move freely, and there’s no tenderness. With nothing obvious to find, the GP reassures the family and advises them to return if things don’t settle.

A few days later, the child presents again. He’s still limping, and his mother says it’s getting worse. At times, he refuses to put any weight on the leg at all. He seems more tired and hasn’t been eating as well – though he hasn’t had a fever, and your observations are within normal limits: HR 100, Temp 36.9°C.

The child occasionally mutters ‘ow’ when moving his leg, but there’s no obvious focus. Again, the GP examines him thoroughly: still no swelling or warmth, no joint restriction. They suspect the soft tissue injury is simply taking time to settle. The patient is reassured again and safety-netted.

At a third appointment a week later, the child is noticeably quieter and less animated than before. The GP decides to ask the opinion of a senior colleague, who takes a fresh history. The mother casually mentions something new: ‘Actually, now I think of it… he wasn’t quite right even before the party. He was a bit off and maybe limping slightly then too. We just assumed he was being clumsy. He’s waiting for an OT assessment anyway.’

The senior GP conducts a very careful examination. There is still no hip or ankle tenderness, or obvious swelling, but when the lower thigh is gently palpated, the child winces – just slightly – when pressure is applied above the knee. This subtle reaction had not been elicited in previous examinations.

What do you think the diagnosis might be? How would you proceed? Put your suggestions in the comments below. Answer to be revealed in the coming weeks!

For more diagnostic puzzles, see previous articles in our Case of the month series:

• Case of the month answers: What was causing this patient’s nausea and tingling fingers? – Pulse Today
• Case of the month answers – what was causing this patient’s panic episodes? – Pulse Today
• Case of the month – answers: Did you get the cause of the patient’s sudden memory loss? – Pulse Today
• Case of the month answers: Did you get what caused this man’s pityriasis rosea? – Pulse Today
• Case of the month answers – what was the cause of this young worker’s abdominal pain? – Pulse Today

Have you handled a case which had a slightly surprising outcome? Perhaps an elderly man with non-vertigo dizziness? Or an unexpected cause of bradycardia? Would you like to share your case studies with us to help support and inform GPs? Please get in touch if you would like to contribute! [email protected]