Fig. 2. (A) The surfaces of bone. Cortical bone volume comprises both the mineralized bone matrix volume and the void volume formed largely by the intracortical canals traversing it. Thus, cortical bone matrix volume is 'inside' the periosteal surface and 'outside' the intracortical and endocortical surfaces upon which remodelling is initiated. Trabecular bone is contained within the trabecular surfaces which are contiguous with the endocortical surface. (B) Remodling upon the intracortical surface enlarges the canals so that with time they coalesce forming giant pores in cross section with fragment the cortex so it is trabecularized. By failing to maintain the anatomical location of the cortical compartment and medullar compartment (broken white line) errors occur in ascribing the matrix and void volumes to the correct location. Including a transitional zone helps to avoid these errors (see text).
