FREE VASCULARIZED FIBULAR GRAFTS - RADIOGRAPHIC EVIDENCE OF REMODELING AND HYPERTROPHY

OBJECTIVE. A study was undertaken to determine the growth potential and radiographic appearance of a free vascularized fibular graft as it responds to the mechanical and physiologic features of its new environment. MATERIALS AND METHODS. In a 10-year period, 30 patients underwent reconstruction of a large skeletal defect with a vascularized fibular graft. Radiographic studies were adequate for assessing sequential changes in 21 patients. Hypertrophy was evaluated by serial measurements of the periosteal and endosteal dimensions and was assessed with respect to age, sex, duration and location of the graft, the indication for reconstruction, and fixation apparatus. RESULTS. Hypertrophy of vascularized bone grafts is not rare. Among 21 vascularized fibular grafts, a measurable degree of hypertrophy was found in eight. Hypertrophy was caused by periosteal formation of new bone. The amount of hypertrophy could be considerable; in some cases it reached 2 cm of new cortical bone, resulting in an unusual radiographic appearance of marked cortical thickening. The amount of hypertrophy was greatest in young males, but was independent of diagnosis and site, and could be seen even in grafts bridged by metallic plates. CONCLUSION. Hypertrophy of vascularized bone grafts is a relatively frequent finding and has distinctive radiographic features. It is unclear why hypertrophy occurs to a much greater extent in some grafts than in others.