Table 2. Histological classification by modified Petty et al. (1985).

	Periosteum	Cortex	Medullary canal
0	Absence of reaction	Small Haversian canals, subperiosteal resorption, absence of polymorpho-nucleated leukocytes	Absence of inflammatory cells or foci of intact polymorpho-nucleated leukocytes
1	Laminated with 1–2 layers	Occasional polymorph nucleated leukocytes in Haversian canals	Diffuse polymorpho-nucleated leukocytes
2	Sunburst type	Focally enlarged Haversian canals filled with granulation tissue, fragmented polymorpho-nucleated leukocytes and osteoclasts	Diffuse intact and fragmented polymorpho-nucleated leukocytes, several micro abscesses
3	Florid, sunburst type	Subperiosteal, endosteal and intracortical resorption, fragmented polymorpho-nucleated leukocytes and micro abscesses, many osteoclasts	Several micro- and macroabscesses in diffuse polymorpho-nucleated leukocytes