Chronic osteomyelitis is diagnosed mainly by

* SEQUESTRUM -- is a piece of dead bone , surrounded by infected granulation tissue trying to "eat" the sequestrum away. It appears pale having smooth inner surface and a rough outer. * When SEQUESTRUM IS COMPLETE, it lies in the free cavity and is LESS attacked by granulation tissue and is absorbed more slowly. * Meanwhile , the surrounding living bone attempts to wall off the infection by forming a thick , dense wall , the INVOLUCRUM. * (INVOLUCRUM is the dense sclerotic bone overlying the sequestrum). * An involucrum usually has multiple openings, the cloacae , through which exudate , bone debris , and sequestra find exit and pass through sinus tracts to the surface. * CONSTANT DESTRUCTION of neighboring soft tissue leads to THIN skin which is easily traumatised , skin epithelium grows inwards to line the sinus tract. * In chronic osteomyelitis of long standing , multiple cavities and sequestra exist throughout the bone * The shaft becomes thickened , irregular and deformed. ref : maheswari 9th ed