Osteomyelitis is a progressive infection of the bone and bone marrow resulting in inflammatory destruction of the bone, necrosis, and new bone formation.  It can occur following hematogenous or contiguous spread of infection.

• Classic hematogenous spread is from S. aureus in pediatrics  or salmonella in patients with sickle cell anemia. It most commonly affects the metaphysis of the tibia (50%), femur (30%), or fibula (12%).
• Contiguous infections tend to be polymicrobial and most commonly occurs after trauma, with ulcers, and in patients with diabetes and vascular insufficiency.