Epidemiology

Neonatal Osteomyelitis

Prognosis

Exogenous osteomyelitis

Subacute Hematogenous Osteomyelitis

Compared with acute osteomyelitis, subacute hematogenous osteomyelitis has a more insidious onset and lacks the severity of symptoms, which makes the diagnosis of this disorder difficult. Subacute osteomyelitis is relatively common. Jones et al. reported that 35% of their patients with primary bone infections had subacute osteomyelitis.

Because of the indolent course of subacute osteomyelitis, diagnosis typically is delayed for more than 2 weeks. Systemic signs and symptoms are minimal. Temperature is only midly.

With exogenous disease, the spread of infection may be the result of (1) direct trauma and the inoculation of infectious material in compound fractures; (2) iatrogenic causes, such as surgical procedures (eg, internal fixation of fractures, joint replacement); and (3) contiguous spread from soft tissue infections surrounding the bone, especially in individuals with diabetes.

The prognosis varies but is markedly improved with timely diagnosis and aggressive therapeutic intervention.

Acute osteomyelitis, although a rare complication in neonates, is a diagnostic and therapeutic challenge. Due to their immature immune response neonates are more susceptible to osteomyelitis than are older children. Preterm infants are at high risk for osteomyelitis because of frequent blood drawing, invasive monitoring/procedures and intravenous drug administration. Early diagnosis of neonatal osteomyelitis might be difficult because of the paucity of clinical signs and symptoms, but has to be included in the differential diagnosis when late-onset or prolonged neonatal sepsis is present, as outcome is dependent on rapid diagnosis and immediate start of treatment.

In Western countries the incidence of osteomyelitis and septic arthritis is 5-12 per 100.000 infants. The overall incidence rate for bone and joint infections is 0.12 per 1000 live births and 0.67 per 1000 neonatal intensive care (NICU) admissions, with a mortality rate of 7.3%. Some recent studies have reported an estimated incidence of 1-7 per 1000 hospital admissions for neonatal osteomyelitis. In a review of more than 300 cases of neonatal osteomyelitis male infants are seen to predominate over females (1.6:1) and preterm infants to be at higher risk than term infants. Risk factors for osteomyelitis and septic arthritis in preterm infants are mostly iatrogenic, including invasive procedures, intravenous or intra-arterial catheters, parenteral nutrition, ventilatory support, and bacteremia with nosocomial pathogens. Two subgroups of neonates are affected: premature neonates with prolonged hospitalization and otherwise healthy newborns presenting within 2 to 4 weeks of discharge.