Vascularised fibula graft inlaid in a massive bone allograft: Considerations on the bio-mechanical behaviour of the combined graft in segmental bone reconstructions after sarcoma resection

Abstract

Vascularised fibula transfer (VFT) is a trustworthy procedure in the reconstruction of skeletal defects secondary to several pathological conditions. Over the last 20 years, progress in diagnosis in skeletal oncology and in adjuvant therapy has increased the possibility of applying limb-saving procedures in the treatment of bone sarcoma. In this context, VFT appeared to be a valuable reconstructive tool following the wide segmental resection of the long bones of the limbs. The vascularized fibula allows for fast bone fusion. It also demonstrates a tendency of progressive hypertrophy and, in those instances in which it is associated with an avascular massive bone allograft (MBA), it induces a process of osteo-integration which enhances the biomechanical properties of a combined graft. In order to assess the progression of the morphologic and structural changes of combined bone grafts we reviewed a group of 31 bone sarcoma patients who had had tibia reconstruction with a VFT inlaid in a massive allograft. Patients had been operated on between 1994 and 2006. Ages ranged from 4 to 31 years (mean 14 years). Thirty patients had received neo-adjuvant chemotherapy. Morphological variations were investigated by means of serial X-ray and CT scan examinations. All patients were regularly reviewed over an average time of 75 months (range 14-154 months). Computer assisted analysis was repeated at every control and performed at the same levels within the reconstruction, so that subsequent CT exams could be compared. We measured the sagittal and transverse diameters, total and medullary area, cortical thickness and cortical density of the VFT. Cortical thickness and cortical density of the massive bone allograft were measured as well. Two different remodelling patterns of the combined graft could be noted over time, that depended on the load trend on the vascularised fibula and that varied according to the persisting integrity of the allograft shell.