Editors

MarkusPääkkönen

Osteomyelitis and Septic Arthritis in Children

Osteomyelitis or septic arthritis should always be suspected in a febrile child with acute limb symptoms.

Paediatric acute osteomyelitis and septic arthritis are serious infectious diseases, but both are rare in the industrialised countries.
More common in boys than in girls (2:1)
In some cases, the infection may be precipitated by trauma (picture 1).
In children, the infection is usually caused by a pathogen that travels haematogenously to the bone or joint.
The most common causative organisms are Staphylococcus aureus (particularly in osteomyelitis), pneumococci, Group A streptococci and, in unvaccinated children, Haemophilus influenzae type B.

An abrupt onset of swelling, redness, heat and tenderness in a limb or joint
Fever
Particularly in young children, the symptoms may be vague (inability to support weight, irritability, crying, the child looks unwell).

See also Arthritis in children Arthritis in Children.
CRP, ESR, complete blood count
CRP < 20 mg/l and ESR < 20 mm/h practically rule out a septic infection, provided that symptom onset occurred 24-48 hours previously. In such cases alternative diagnoses must be considered, of which the following require immediate identification and referral to specialist care: leukaemia, epiphysiolysis of the hip Hip Pain in Children and a fracture Upper Limb Injuries in Children. Non-urgent referral is indicated for a child if juvenile arthritis Juvenile Idiopathic Arthritis (Juvenile Rheumatoid Arthritis) or enteroarthritis is suspected.
- Hip synovitis Hip Pain in Children can be managed in primary care provided that there is no doubt about the diagnosis.
If a septic infection cannot be excluded, the patient must be sent to a hospital for the collection of a culture sample before antimicrobial therapy is started.

Diagnostic samples are often obtained under anaesthesia. Performing arthrocentesis in a child patient at an emergency department may also be carried out using nitrous oxide anaesthesia.
Intravenous antimicrobial therapy can be started as soon as the necessary samples have been obtained.
Clindamycin 40 mg/kg/day or a first-generation cephalosporin 150 mg/kg/day, divided into four doses. It is usually possible to switch to oral treatment after 2-4 days.
The duration of treatment is 20 days in osteomyelitis and 10-14 days in septic arthritis.

With timely therapeutic intervention the majority of patients recover fully.
Feared complications include chronic osteomyelitis, pathological fractures, destruction of the articular cartilage and aseptic necrosis of the femoral head.

Pääkkönen M, Peltola H. Management of a child with suspected acute septic arthritis. Arch Dis Child 2012;97: 287-92 [PubMed]
Peltola H, Pääkkönen M. Acute osteomyelitis in children. N Engl J Med 2014;370(4):352-60. [PubMed]