4-year-old male child.

Brought in by mother because of acute onset of limp ("he woke up like that").

No fever, no signs of infection recently, temperature normal.

Extremely difficult to examine initially according to mother: unable to localise pain due to his age and her verbal communication (for her age normal).

She has been seen three days earlier at St Elsewhere and has had a pelvic X-ray which is normal (you check on the web based system). However, mum thinks the other hospital is rubbish so has come to you.

Can you get it sorted as he needs to play football on Saturday.