Fever and Pain
Kevin is an 18-month old boy who presents to the paediatric day unit with a 4-week history of temperatures and reluctance to weight-bear. The onset of symptoms coincided with return from a family holiday to a resort in Turkey, where he had had a brief diarrhoeal illness but had otherwise been well. His mother recalls him refusing to be put down on his feet and instead dropping onto his bottom when they returned home. He had come to A&E at this stage, where his temperature was 38.5’C and had an x-ray of his hips, which was reported as normal although difficulty in positioning was noted.
He subsequently continued to spike temperatures of 38-39’C which were only briefly relieved by paracetamol and ibuprofen, which he had been taking regularly throughout the illness. During this time his mobility varied between complete refusal to mobilise to cruising round furniture, and seemed to be transiently improved following paracetamol or ibuprofen. His mother reported that he had previously been very active and used to run without difficulty. She had noticed that he seemed to be in pain when she changed his nappy. In the week prior to admission he had been waking at night crying with pain.
His weight at 8.6kg was on the 2nd centile. Examination revealed a small, miserable, uncomfortable child with a temperature of 39.2’C. Heart rate was 160 beats per minute with a systolic murmur. His chest was clear, with no coryza. His abdomen was soft and non-tender, with a 1-2cm liver edge but no other organs felt. He had inguinal and cervical lymphadenopathy. Ear, nose and throat examination was unremarkable. There was no bruising, erythema or petechiae on his skin. Joint examination showed no swelling, redness or increased temperature at any joint; range of passive movement was normal everywhere apart from the right hip, where internal rotation caused him to cry and wriggle away.
Fever, and refusal to weight bear.
Septic arthritis; note that x-rays can be normal at presentation. Check inflammatory markers and have a low threshold for further imaging such as ultrasound or MRI scans. If septic arthritis is being considered, discussion with orthopaedics and infectious diseases colleagues is mandatory.
Continuing to spike temperatures despite having variable mobility, length of time of symptoms, transient improvement with anti-inflammatories.
A referral to paediatric rheumatology or orthopaedics could have been made. He could have had blood tests including inflammatory markers and autoantibodies, and scans such as hip ultrasound or MRI. Also, consider x-rays of knees as well as hips in a child with a limp.
Osteomyelitis, Perthes disease, Juvenile Idiopathic Arthritis, Leukaemia, Primary Bone Tumour, Developmental Dysplasia of the Hip, and Transient Synovitis of the Hip may all have been on the initial differential diagnosis.
Look carefully for petechial rash, lymphadenopathy and hepatosplenomegaly which may suggest malignancy such as Leukaemia. Restricted hip rotation in an otherwise well child may be Perthes Disease. Joint swelling or restricted joint movement of other joints may suggest Juvenile Idiopathic Arthritis (isolated involvement of a hip joint is unusual). In a well child, with normal examination and investigations, Transient Synovitis of the Hip is likely. Fever and an unwell child are consistent with infection (septic arthritis or osteomyelitis) but may also occur in malignancy.
Kevin looked a little better and his temperature came down with a further dose of paracetamol. Full blood count showed haemoglobin 75g/l, platelets 258 x106, white cell count 10 x 106.1; C-reactive protein 89 (normal <10mg/L). Hip ultrasound scan demonstrated a small effusion and he was taken to theatre for a hip aspiration. Blood cultures were positive for staph aureus. Repeat x-ray of his hip showed erosion in the iliac bone on the right side, in keeping with osteomyelitis.