Dolph Houben

98 CHAPTER 5 Methods Experimental Design The Institutional Animal Care and Use Committee approved this study and all experiments were performed according to the established National Institutes of Health guidelines. Fourteen Yucatan miniature swine underwent orthotopic tibial bone VCA reconstruction in combination with surgical induced neo-angiogenesis and short-term immunosuppression. Seven living male Yucatan swine provided 14 vascularized tibia segments (VCAs). The allotransplant harvest, creation of the defect, transplantation, and fixation were performed largely as previously described, modified with proximal dissection of the vascular pedicle to include the superficial femoral artery and vein [13] (Fig. 1). One donor provided a pair of vascularized tibial segments for transplantation: one each from the left and right hindlimb. The ipsilateral hindlimb was used in each of two recipient swine. Donor and recipient were matched by age (mean 5.8 months), size (15-35kg) and blood type (type A). The animals were mismatched by pre-operative DNA sequence haplotyping to ensure five to ten class I and II swine leukocyte antigen (SLA) mismatches. Figure 1: (A) 3.5 cm tibia segment with vascular pedicle showing the nutrient artery entering the graft by the nutrient foramen, (B) microsurgical anastomosis of the vascular pedicle to the femoral artery in a side-to-end fashion and the vein in an end-to- end fashion, (C) radiographic evaluation post-operative showing the reconstruction with internal fixation Donor VCA Harvest A single nutrient artery supplying the proximal tibial diaphysis is consistently found on its posterior surface 1-2 centimeters distal to the tibial tubercle. The nutrient pedicle is a branch of the caudal interosseous artery and vein. Briefly, the tibial VCA segment is harvested through an anterolateral incision, exposing the interosseous membrane and both cranial and caudal interosseous vessels. The proximal cut is made distal to the tubercle but proximal to the nutrient foramen. The distal cut is next made with a cutting jig to ensure uniform dimensions (Fig.1A). Proximal dissection of the pedicle to include the superficial femoral artery and vein completed the VCA harvest. The larger diameter of the femoral pedicle simplified the arterial anastomoses and enabled an end-to-end venous anastomosis not possible with the previously-described method (Fig.1B).