Osteomyelitis

Definition and Epidemiology

• Osteomyelitis is an infection of bone and bone marrow, either acute or chronic in nature.
• It can occur at any age, with different bacteria predominant in different age groups.
• Commonly caused by Staphylococcus aureus, but can be due to a variety of organisms depending on the route of infection.

Pathophysiology

• Infection typically reaches the bone through one of three pathways: hematogenous spread, contiguous spread from adjacent tissue, or direct inoculation (e.g., trauma, surgery).
• Hematogenous osteomyelitis is more common in children, often affecting the metaphyseal areas of long bones.
• In adults, contiguous spread from soft tissue infections or diabetic foot ulcers is more common.
• The infection leads to an inflammatory response, bone necrosis, and new bone formation (involucrum).

Clinical Features

• Localised bone pain, swelling, redness, and warmth.
• Systemic symptoms: fever, chills, malaise.
• In chronic osteomyelitis, symptoms are more insidious, including persistent pain and sinus tract formation.
• In diabetic patients, often presents in the feet with neuropathic ulcers.

Diagnosis

• High clinical suspicion based on history and physical examination.
• Laboratory findings: Elevated white blood cell count, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP).
• Imaging: X-rays, MRI, and CT scans can identify bone changes.
• Bone biopsy and culture for definitive diagnosis and antibiotic sensitivity.

Management

• Early and aggressive antibiotic therapy, initially intravenous followed by oral.
• Antibiotic choice based on suspected or confirmed causative organism.
• Surgical intervention may be necessary for debridement of necrotic bone, abscess drainage, or to address any source of contiguous spread.
• In chronic cases, long-term antibiotic therapy and multiple surgeries may be required.

Complications

• Chronic infection leading to bone destruction and deformity.
• Systemic spread of infection, potentially leading to sepsis.
• Amputation in severe cases involving the extremities.

Prognosis

• Early treatment in acute osteomyelitis generally leads to good outcomes.
• Chronic osteomyelitis has a more protracted course and can be challenging to eradicate completely.