ABSTRACT
Regardless of the initial route of entry, established bone infection causes increased intramedullary pressure and microthrombosis, often creating infarcted areas of dead bone known as sequestra. Having no blood supply, sequestra that are not resorbed behave as foreign bodies and provide a sanctuary where viable bacteria may continue to exist indefinitely, safely beyond the reach of both antibiotics and the immune system. If sequestra persist, the risk of treatment failure or relapse is high. Often chronic infection results with intermittent or chronic drainage from sinus tracts (fistulas) that eventually develop between the bone and the overlying skin. Although seldom encountered in adults, involucra (concentric layers of new bone that develop around a focus of osteomyelitis) can also lead to persistent infection. Thus, even seemingly ‘‘cured’’ osteomyelitis may occasionally relapse, sometimes decades later. For this reason ‘‘arrest’’ rather than cure may be the more appropriate way of thinking about chronic bone infections.
