Intermittent Limp 2
A 6 year old child presents with an intermittent limp - worse after school (with some aches in his legs) and if he has been playing football. There has been no trauma noted and he is otherwise well with no fever and his appetite is good. He presents to his GP and his parents are concerned that he has growing pains. They seek advice on how to manage his pain.
Examining him demonstrates a limping gait and discomfort on moving his right hip. Otherwise he looks well but has a low grade fever. His testes and abdomen are non-tender and appear normal.
These are not growing pains because he has a limp, day time symptoms, restricted range of his hip movement and he has a low grade fever. Clearly his presentation is not consistent with the rules of growing pains.
Investigations need to exclude infection and malignancy.
Blood tests are normal (full [complete] blood count, inflammatory markers and peripheral blood film). Radiographs of his hips are normal. Ultrasound of his right hip demonstrates a small effusion.
This is likely to be a transient synovitis or irritable hip but in view of his low grade fever he is kept under observation. He is more unwell the next day and again has a fever. Repeat blood tests show a raised white cell count. Blood cultures from the day before are still negative. Repeat ultrasound scan again shows a collection at the right hip. He is taken to the operating theatre, the hip irrigated and the fluid sent for synovial fluid analysis and culture. He is started on antibiotics on the assumption that this is septic arthritis. His CRP is raised (15mg/L) and white cells raised at 13x106/L. His fever settles and his blood tests return to normal. Subsequent blood cultures are negative. He completes his antibiotic course, along with physiotherapy and has a full recovery. His follow-up includes repeat radiograph of his hips as sometimes an avascular necrosis similar to Perthes’ disease can develop after transient synovitis.