Definition and Pathophysiology

Neonatal osteomyelitis is an inflammation of the bone and bone marrow.
It is usually bacterial in origin and frequently coexists with septic arthritis in newborns.
Infection often results from hematogenous seeding during bacteremia.
It may also occur via direct extension from a local skin infection.
In neonates, metaphyseal blood vessels communicate directly with epiphyseal vessels.
This anatomy allows infection to spread rapidly from the metaphysis to the epiphysis and into the joint cavity.

Etiology and Affected Sites

Aspect	Characteristics
Common Organisms	Staphylococcus aureus (most common), Klebsiella pneumoniae, Group B Streptococcus, and E. coli.
Other Pathogens	Enterobacter, Kingella, Candida, and N. gonorrhoeae.
Common Joint Sites	Hips (most common), followed by the knee, elbow, shoulder, and ankle.
Common Bone Sites	Femur, humerus, tibia, radius, and maxilla.

Signs and symptoms are often pauci-symptomatic or nonspecific in early stages.
Infants may present with refusal to feed and inconsolable crying.
Temperature instability (hypo or hyperthermia) is common.
Localizing signs include swelling, erythema, and increased warmth of the affected joint.
Pseudoparalysis (reduced or absent spontaneous movement of the involved limb) is a key diagnostic clue.
Irritability is often noted when the affected part is handled.

Blood cultures must be obtained before starting antibiotics.
Confirmatory diagnosis is made via bacterial cultures from bone aspiration or surgical debridement.
Elevated sepsis biomarkers, such as C-reactive protein (CRP) and white blood cell count (WBC), are typically present.

X-ray: Bone destruction signs appear within 7 days of infection in neonates, which is earlier than in older children.
Ultrasound (USS): This is highly sensitive for acute findings, including elevated periosteum and subperiosteal collections.
MRI: Indicated when clinical suspicion remains high despite a normal ultrasound report.

Initial empiric antibiotics should be chosen based on regional resistance patterns.
Common choices include IV cefotaxime, vancomycin, or clindamycin.
Staphylococcal infections require a minimum of 2 to 3 weeks of therapy.
The total duration of parenteral therapy is typically 3 to 4 weeks, though some cases require 6 to 8 weeks.

Orthopedic and anesthesia teams should be involved early.
Needle aspiration of the infected joint is often performed for diagnosis.
There is general agreement favoring arthrotomy for the debridement of infected joints.

Newborns require long-term follow-up by pediatricians and orthopedicians until at least age five.
Significant disability can occur from damage to the joint or growth plate.
Late complications include avascular necrosis of the bone, limb shortening, and progression to chronic osteomyelitis.