Neonatal osteomyelitis is defined as a bacterial infection of bones and differs from what is seen in older children and adolescents. The incidence of osteomyelitis ranged from approximately 1 in 5000 to 7700 children and boys are affected nearly twice as often as girls. Douglas, in British Medical Journal 1898, reported the first case of osteomyelitis in infants. Associated risk factors include prematurity, low birthweight, preceding infection, bacteremia, exchange transfusion and the presence of an intravenous catheter.
Due to the bone anatomy and blood supply in neonates, osteomyelitis often co-exists with septic arthritis, while the last one can occur alone; the epiphysis receives its blood supply directly from metaphyseal blood vessels and the adjacent cartilaginous growth plate is traversed by capillaries, allowing spread of the pathogenic bacteria to the physis, epiphysis and joint Fig. 1 . Neonatal osteomyelitis arises regularly as a consequence of hematogenous spread of microorganisms. The most common bacterial pathogen in neonates is Staphylococcus aureus, Group B streptococcus (Streptococcus agalactiae), gram-negative organisms (E. coli and Klebsiella pneumonia) and in recent years community-acquired strains of methicillin-resistant Staphylococcus aureus.
Clinical symptoms of osteomyelitis in the neonates are unspecific and usually mild and include temperature instability, feeding intolerance, reduced movement and as the disease progresses, disability, local swelling or erythema. Focal tenderness over a long bone and subcutaneous abscess formation prompts the diagnosis of osteomyelitis.
The lower extremities account for 75% of the infections in children, with the femur (27%), tibia (26%), pelvis (9%) and feet being the most common locations Fig. 2 .
Radiological investigations confirm the suspicion of neonatal osteomyelitis, define the infection site, differentiate between unifocal and multifocal disease patterns. Magnetic resonance imaging has high specificity (94%) and sensitivity (97%) for the diagnosis of acute osteomyelitis, showing detailed anatomic presence of the inflammatory process and its complications.
Successful cure of osteomyelitis during the newborn period is dependent on a fast diagnosis and sufficient treatment. Antibiotic and antimicrobial therapies should be started as soon as the diagnosis is made and directed against the most common bacterial isolates responsible for hematogenous osteomyelitis according to age group. Delay in therapy commencement increases the risk for complications. Surgery is indicated to drain acute abscesses or when no improvement is achieved with antibiotic treatment.