Osteomyelitis Flashcards
Define osteomyelitis.
Inflammation of the bone, usually caused by bacterial infection. Bone infection in children are primarily haematogenous in origin, although cases secondary to penetrating trauma, surgery, or infection in a contiguous site are also reported.
Explain the aetiology of osteomyelitis.
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.
Which pathogens cause osteomyelitis?
- Most common pathogen is Staphylococcus aureus, followed by Streptococcus pneumonia and Streptococcus pyogenes.
- 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.
- Salmonella is an important cause of osteomyelitis in children with sickle cell disease.
Summarise the epidemiology of osteomyelitis.
50% of cases occur in preschool-aged children.
Chronic osteomyelitis is frequently reported in developing countries where medical and surgical treatment modalities are not commonly accessible. 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 behaviour or other physical activities that predispose to bone injury.
What are presenting symptoms of osteomyelitis?
Long bones, including the femur, tibia, and humerus, are most commonly affected.
Fever, bone 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.
What are the signs of osteomyelitis?
Often, patients are able to localize the infected bone on examination, owing to pain.
Symptoms include focal swelling with cardinal signs of inflammation with or without fever and focal point tenderness over the affected bone. It is important to note whether the adjacent joint is involved by assessing the range of motion of the joint and signs of inflammation. Arthritis found on examination may be a reactive inflammatory response or a sign of an infected joint.
Draining sinus and bone deformity are both rare in acute disease. When present, these symptoms suggest subacute or chronic osteomyelitis.
What are appropriate investigations for osteomyelitis?
FBC, CRP/ESR
Blood, bone or joint aspirate culture (obtain them before giving antibiotics)
X-ray (10-14 days before changes appear)
USS/MR/isotopeI, bone biopsy
What is the management for osteomyelitis?
IV antibiotics: e.g. flucloxacillin, benzylpenicillin. Always be guided by your local antiobiotic regimen. Neonates and infants will need IV antibiotics for the entire course of treatment. Consider long line placement.
Limb splintage in position of safety, non-weight bearing.
Surgical debridement if:
- Failure to respond to IV antibiotic.
- Frank pus on aspiration
- Presence of sequestered abscess.
When fever and pain resolve, and inflammatory markers normalizing, convert to oral antibiotics. Treat for a minimum of 4-6 weeks with progress monitored by temperature, WCC, CRP, ESR.
What are complications associated with osteomyelitis?
Septic arthritis, recurrence within 1 year after treatment (<4%)
Chronic osteomyelitis (<5%)
Growth arrest secondary to physeal damage.
What is the prognosis of osteomyelitis?
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.
