Practice Essentials
Osteomyelitis, or inflammation of the bone, is usually caused by bacterial infection. Bone infections in children are primarily hematogenous in origin, although cases secondary to penetrating trauma, surgery, or infection in a contiguous site are also reported. Clinical suspicion is always helpful to obtaining a correct diagnosis.
Signs and symptoms
Long bones, including the femur, tibia, and humerus, are typically affected.
Fever, localized pain, swelling, redness, and guarding the affected body part are common.
Inability to support weight and asymmetric movement of extremities are often early signs in newborns and young infants.
See Presentation for more detail.
Diagnosis
Laboratory studies
Among the tests included in the workup are the following:
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White blood cell (WBC) count
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C-reactive protein (CRP) level
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Erythrocyte sedimentation rate (ESR)
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Blood, bone, or joint aspirate cultures
Imaging studies
The following studies can be useful in the workup:
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Magnetic resonance imaging (remains the gold standard)
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Radiography
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Three-phase technetium radionuclide bone scanning (used less commonly)
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Ultrasonography
See Workup for more detail.
Management
Optimal antibiotic selection, adequate dosing, and a sufficiently prolonged antibiotic course with monitoring for clinical response and for toxicity of the therapy are essential.
The decision must be tailored to the age of the patient, local resistance patterns, pathogen suspected, and compliance with the agent prescribed.
Promptly initiate antibiotic treatment, preferably after obtaining blood and bone aspirates for culture. Initially, select one or more antimicrobial agents that provide adequate coverage for common pathogens, until therapy can be narrowed.
See Treatment and Medication for more detail.
Pathophysiology
Approximately 50% of cases occur in preschool-aged children. Young children primarily experience acute hematogenous osteomyelitis due to the rich vascular supply in their growing bones. Circulating organisms tend to start the infection in the metaphyseal ends of the long bones because of the sluggish circulation in the metaphyseal capillary loops. The presence of vascular connections between the metaphysis and the epiphysis make infants particularly prone to arthritis of the adjacent joint. Involvement of the shoulder joint or hip joint is also noted when the intracapsular metaphyseal end of the humerus or femoral is infected. If untreated, infection can also spread to the subperiosteal space after traversing the cortex.
Etiology
Staphylococcus aureus is the most common pathogen, followed by Streptococcus pneumoniae and Streptococcus pyogenes. Community-associated methicillin-resistant S aureus (CA-MRSA) continues to be a major and most common cause in many regions of the United States. [1, 2, 3, 4]
Gram-negative bacteria and group B streptococci are frequently seen in newborns.
Pseudomonas aeruginosa is often associated with osteomyelitis and osteochondritis following penetrating wounds of the foot through a tennis shoe.
Children who are immunocompromised are prone to infection with various fungi and bacteria, in addition to common pathogens.
Bony lesions due to Bartonella henselae (cause of catscratch disease) have also been reported.
Salmonella is an important cause of osteomyelitis in children with sickle cell disease and other hemoglobinopathies.
Kingella kingae, a fastidious gram-negative rod, is increasingly recognized as a cause of osteoarticular infections, particularly in the first 2 years of life and following a respiratory tract infection.
Anaerobes such as Bacteroides, Fusobacterium, Clostridium, and Peptostreptococcus rarely cause osteomyelitis.
Epidemiology
United States statistics
The exact frequency is unknown as osteomyelitis is not a reportable disease.
International statistics
Chronic osteomyelitis is frequently reported in developing countries where medical and surgical treatment modalities are not commonly accessible.
Race-, sex-, and age-related demographics
Few studies have commented on race differences.
A preponderance in males is observed in all age groups. Factors related to increased incidence in males may include increased trauma due to risk-taking behavior or other physical activities that predispose to bone injury.
One half of cases occur in preschool-aged children.
Prognosis
Despite adequate treatment and appropriate surgical intervention, 5-10% of patients may experience recurrence.
Aggressively treat any recurrence in consultation with an orthopedic surgeon and infectious diseases specialist. Recurrences may lead to chronic osteomyelitis with discharging sinuses and other systemic sequelae.
Morbidity/mortality
As noted in recent studies, patients may develop deep vein thrombosis and fractures. [5, 1, 6, 7]
Complications
Possible complications from osteomyelitis include disturbances in bone growth, limb-length discrepancies, arthritis, abnormal gait, and pathologic fractures. In patients with chronic osteomyelitis, bone necrosis and fibrosis can occur. In a Swedish study of 430 children with acute osteomyelitis, severe complications occurred in 14 children and 5 of them required intensive care. [8]
Monitor patients for septic thrombophlebitis, venous thrombosis, and pathologic fractures. [9]
Leg-length discrepancy is due to involvement of the growth plate with infection.
Patient Education
Discuss age-appropriate care with the patient to ensure compliance with medical therapy.
It is important to ensure familial compliance with proper dosing of antibiotics when choosing an appropriate oral regimen.
