Dolph Houben

85 Outcomes of vascularized bone allotransplantation 4 Figure 4: Lateral radiographs of the reconstructed tibia post-operative and at 2,4,6,10 and 20 weeks after transplantation. The white arrows indicate the periosteal bridging arising from the viable allotransplant observed two weeks after transplantation. Table 1: radiographic healing scores based on X-rays at 20 weeks* X-RAY (scores) Group 1 Group 2 P-value Periosteal Bridging Proximal 4 4 1 Periosteal Bridging Distal 3.83 4 0.31 Callus Remodeling Proximal 4 4 1 Callus Remodeling Distal 3.33 3.66 0.60 Union Proximal 4 4 1 Union Distal 3 3.3 0.58 Transplant appearance 0.67 0.67 1 Total score (25 point = max) 22.83 23.67 0.60 *Values are given in means, 0-4 points could be given except for transplant appearance (0-1 point) Bone Material Properties All material properties of bone were evaluated 20-weeks after transplantation. Bone Mineral Density (BMD) measurements of the allotransplants with micro-CT showed the BMD was maintained in both groups. Bone porosity measurements showed a trend (p=0.06) towards a higher percentage of bone porosity in the allotransplants compared to the contralateral side (Table 2). The median elastic modulus (Mpa) of the allotransplants calculated by axial compression testing was lower than contralateral normal bone (Fig. 5), regardless of the patency of the implementation of an AV-bundle. The median elastic modulus significantly differed from contralateral normal control bone in both groups (p=0.03). No significant difference was found between the two intervention groups. Cyclic RPI of the allotransplant and of normal bone was conducted in the axial direction. The measurements showed a significant difference for TID and NIDI compared to contralateral normal bone (Table 3). No statistically significant difference could be found for the implantation of an AV-bundle. Cyclic RPI of the one 6-week survival allotransplant did not differ when compared to the 20-week samples. Assessment of bone material properties measured with micro-CT and biomechanical testing showed material properties of both allotransplant groups are diminished compared to normal (contra-lateral) bone at 20 weeks after transplantation.