Etiology, Pathogenesis, and Clinical Features of Osteomyelitis

Osteomyelitis is an inflammatory condition affecting bone, typically due to an infectious agent. This condition can arise from hematogenous spread, direct inoculation from trauma, or contiguous infection. Understanding its pathogenesis, clinical manifestations, and complications is crucial for effective management.

Pathogenesis of Osteomyelitis

Mechanisms of Infection

The infection can occur via hematogenous seeding, direct trauma, or extension from nearby tissues. The most common causative organisms include Staphylococcus aureus, Streptococcus species, and Gram-negative bacilli.

Spread and Immune Response

Once bacteria enter the bone, they proliferate and trigger an inflammatory response. Neutrophils attempt to contain the infection, leading to the formation of pus and increased intramedullary pressure, which may cause vascular compromise and necrosis.

Clinical Manifestations

• Localized bone pain and tenderness
• Swelling and erythema over the affected region
• Fever and malaise in acute presentations
• Chronic cases may present with draining sinus tracts

Radiologic and Morphologic Features

Imaging modalities such as MRI and CT scans help in assessing the extent of bone involvement. Typical findings include periosteal reaction, sequestrum formation, and bone erosion.

Complications

Left untreated, osteomyelitis can lead to chronic infection, pathologic fractures, and systemic dissemination.