Osteopontin and bone sialoprotein distribution at the bone graft recipient site

The area in close proximity to a bone graft is subject to marked remodeling activity, which may dramatically affect graft survival.

To specifically analyze the effects at the recipient bed-onlay graft interface.

In 22 adult Lewis rats, bicortical grafts were positioned below the temporal muscle and subperiosteally over the parietal bone. The recipient bone was left intact or ground to remove the external cortical layer, thereby exposing the graft to the osteopotent cells of the bone marrow. The rats were killed after 4 or 20 weeks. The outcome was assessed by routine histologic examination and immunohistochemical labeling for 2 bone matrix proteins, osteopontin and bone sialoprotein, which are involved in bone resorption and formation, respectively.

Placement of the grafts submuscularly or grinding of the outer cortical layer of the host bed increased recipient site resorption. Resorptive activity (labeling) was concentrated to a subzone below the surface of the recipient bone; neither the graft surface nor the interface soft tissues were labeled.

The successive loss of skeletal contour after bone grafting, in many cases, may largely result from recipient site failure rather than graft size reduction.