Autogenous cancellous bone graft incorporation in a gap defect in the canine femur.

While gap defect models provide greater graft stability and are more representative of many clinical situations than segmental defect models, the healing in these models has not been well documented. To study the histologic course of cancellous bone graft healing in a long bone gap defect, 12 adult mongrel dogs were killed in groups of two at 1, 2, 3, 4, 6, and 12 weeks. Graft incorporation in these dogs was studied using macro- and microradiography, histologic sections, and computer-assisted digital surface analysis; results are described. Unlike that seen in segmental defect models, the pattern of repair in a cancellous bone grafted gap defect provides consistent healing at 12 weeks and follows the same healing process seen with stable defects.