Osteomyelitis is a progressive infection of bone that results in inflammatory destruction, followed by new bone formation. Three major categories are based upon pathogenic mechanisms of infection :
●Osteomyelitis secondary to a contiguous focus of infection (eg, after trauma, surgery, or insertion of a prosthetic joint)
●Osteomyelitis secondary to a contiguous focus of infection associated with vascular insufficiency, primarily occurring in patients with diabetes mellitus and/or peripheral vascular disease
●Osteomyelitis following hematogenous spread of infection, which is the major mechanism in vertebral osteomyelitis and in children
Acute osteomyelitis evolves over several days to weeks and can progress to a chronic infection . The hallmark of chronic osteomyelitis is the presence of dead bone (sequestrum). Other common features of chronic osteomyelitis include involucrum (reactive bony encasement of the sequestrum), local bone loss, and, if there is extension through cortical bone, sinus tracts.