PAIN AND FEVER
History
Kyle is a 16-month-old boy who presents to the paediatric day unit with a 2-day history of intermittent inconsolable crying and fevers up to 40C. He has not been interested in food and has vomited twice. There has been no diarrhoea. His parents report that he seems to be in pain when his nappy is changed. He had a cut on his right foot 2 weeks ago which has healed and there is no obvious history of trauma. Kyle was born at term and has no other significant past medical history. Both parents are unemployed and he has two older half-sisters, aged 5 and 3, with the same mother. He is on no regular medication and has no known allergies.
Examination
He looks unwell with a temperature of 38.7C. He dislikes handling and is clearly in pain. His capillary refill time is 4 s and he is mildly dehydrated. His pulse is 135 beats/min and his blood pressure is 75/50 mmHg. There is no skin rash. Examination of the cardiovascular and respiratory systems is unremarkable. His abdomen seems soft with no obvious tenderness or organomegaly. Bowel sounds are normal. There is no meningism. Examination of the ears, nose and throat is normal.
INVESTIGATIONS
Normal
Haemoglobin 12.3 g/dL 11.5–15.5 g/dL
White cell count (WCC) 28.0 109/L 6.0–17.5 109/L
Neutrophils 22.0 109/L 3.0–5.8 109/L
Platelets 325 109/L 150–400 109/L
Erythrocyte sedimentation 78 mm/hour 0–10 mm/hour rate (ESR)
Sodium 140 mmol/L 138–146 mmol/L
Potassium 4.5 mmol/L 3.5–5.0 mmol/L
Urea 3.7 mmol/L 1.8–6.4 mmol/L
Creatinine 46 mol/L 27–62 mol/L
C-reactive protein (CRP) 340 mg/L 6 mg/L
Urine microscopy No abnormality detected
Lumbar puncture No white blood cells, no organisms seen Chest
X-ray Clea
Questions
• What else should you document in the examination?
• What is the most likely diagnosis?
• What imaging modalities would you consider?
• What is the management?
Medicine
This boy has signs of sepsis with fever, prolonged capillary refill time and tachycardia. His investigations support this. The history of pain with movement is strongly suggestive of musculoskeletal pathology. In acute sepsis, the emphasis is usually on diagnosing meningitis or an acute abdomen and it is easy to overlook this system. Examine for any swelling, redness of the skin, warmth and tenderness. There may be nothing to see superficially, so observe the posture and whether the child is keeping any limb flexed or still. Gently examine the range of movement of all joints. The most likely diagnosis is osteomyelitis or septic arthritis. The legs are much the commonest site and most infections are blood-borne. There is often a recent history of minor trauma or a breach in the skin, which probably explains why boys are more often affected. The commonest bacteria involved is Staphylococcus aureus. Children with sickle cell disease have a higher incidence of skeletal infections. The differential depends on the site but includes soft-tissue infections and psoas abscess. In the less obviously septic child, remember trauma, both accidental and non-accidental, and bone infiltration with cancers such as leukaemia.
Possible imaging modalities
• Plain X-rays – excludes trauma. In osteomyelitis, bones are unlikely to be abnormal until 10–14 days after onset. In arthritis they are often normal but may show widening of joint space local soft tissue or fat changes
• Ultrasound (US) – highly sensitive in detecting joint effusion and guiding aspiration. It may demonstrate swelling and distortion of soft tissues and subperiosteal region
• MRI – the best technique to differentiate between soft tissue and bone infection; also to detect a joint effusion where US is normal. However, the boy will need sedation or general anaesthetic at this age
• Technetium (99mTc) bone scan – accumulates as ‘hot spots’ in areas of increased bone turnover so useful in osteomyelitis, especially multifocal. Infection close to growth plates can limit specificity
First, he needs fluid resuscitation and adequate pain relief. If the clinical diagnosis is osteomyelitis, he should start intravenous antibiotics, e.g. co-amoxiclav. However, if there is evidence of septic arthritis, he should ideally have an immediate US and, if there is an effusion, an urgent arthrotomy before starting antibiotics. If there is no effusion, the diagnosis is more likely to be osteomyelitis and antibiotics can be started. They should not be delayed in order to establish a definitive diagnosis with imaging or cultures, because this increases the risk of long-term effects on the growth and function of the affected limb, especially if the growth plate is involved. The length of treatment and route of administration of antibiotics for both depend upon the clinical and biochemical (WCC, ESR, CRP) responses. A total of 6 weeks is common practice. Long-term follow-up is necessary because problems may not be apparent for several years. Most children make an uneventful recovery.
KEY POINTS
• Bone and/or joint sepsis should be considered in the differential diagnosis of all children presenting with sepsis.
• Delay in treatment of osteomyelitis or septic arthritis can cause significant long-term effects on the growth and function of the affected limb.
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