Dolph Houben

160 CHAPTER 8 Orthotopic allotransplantation On the same operative day, a female recipient was anesthetized with Tiletamine HCL + Zolazepam HCl (IM), then intubated and maintained with inhalation anesthesia (Isoflurane 1-3%). Prior to the incision, the right leg was prepped, draped in a sterile fashion and covered with Ioban 2 Antimicrobial Incise drapes. One gram of cefazolin (Hospira, Lake Forest, IL) was administered intravenously for infection prophylaxis. Tacrolimus and mycophenolate were administered by a gastric tube and methylprednisone, intravenously at this time. During the entire procedure, the animal was monitored for heart rate, oxygen saturation, blood pressure, and temperature. Blood and fluid losses were compensated with intravenous administration of Ringer's solution (Baxter Healthcare Corporation, Deerfield, IL). An anteromedial skin incision over the knee was made extending medially to inguinal ligament. The femoral vessels were dissected and prepared for microsurgical anastomosis l (Fig. 2). A pedicled gracilis flap was raised by identifying the main nutrient artery (a branch of the medial circumflex femoral artery), detachment of its origin at the pelvis, and rotated around the longitudinal axis of saphenous artery and vein (Fig.3 A). The saphenous artery gives several small branches to the Gracilis flap which were left untouched (Fig.3B). The anterior compartment musculature was retracted laterally, and the cranial tibial artery ligated distally and mobilized proximally from the surface of the interosseous membrane for later implantation as an autogenous AV-bundle into the tibia (Fig. 3C). The peroneal nerve was identified and preserved. All muscle attachments to the recipient’s autogenic knee were dissected directly from the bone, ensuring tendon preservation for later reconstruction. A biceps femoris muscular branch, was also mobilized for later implantation as autogenous AV-bundle into the femur. The femoral bone cut was made 3cm above the joint line, and the tibia and fibula divided at a level immediately distal to the tibial tubercle. After the bone cuts were made, the femoral artery, popliteal artery, and peroneal nerve were carefully dissected off the posterior knee to maintain limb perfusion. At this point, the knee joint was removed. Transplantation of the allogenic knee was then performed by achieving rigid internal fixation with two retrograde placed intramedullary locked nails (I-Loc IM fixator System, BioMedtrix, Whippany, NJ). The femoral nail was placed in a retrograde fashion, introduced through a capsulotomy in the allotransplant. It was a standard 4-hole 6 X122mm nail, (Cat. No. 34-06-122). The tibia was stabilized with an antegrade-placed locked nail that was custom-made for the porcine tibia with 3 locking holes (6x122mm, Cat No. 34-06-122S). The fibula was not fixed. Intra-operative radiographs verified appropriate rod and locking pin placement. The host-transplant bone contact sites were augmented with bone graft obtained from the recipient's resected bone. Next, end-to-side arterial and end-to-side venous anastomoses were made to the superficial femoral vessels with 8.0 nylon microsuture (Ethicon LLC, San Lorenzo, Puerto Rico) (Fig. 2). All muscles were repaired to their anatomic knee insertion. The joint capsule was closed with 2- 0 and 0 FiberWire sutures (Arthrex, Naples, FL). The pedicled gracilis flap was flipped over the saphenous artery and vein to cover the entire reconstruction (Fig. 3C). A layered closure, use of Dermabond Prineo (Ethicon, LLC, San Lorenzo, Puerto Rico) and wrapping the hindlimb with Tegaderm and Ioban (3M Health Care, St Paul, MN) was performed to minimize the risk of deep infection. A central venous catheter (Hickman catheter, Bard Access Systems, Inc., Salt Lake City, UT) was placed in the internal jugular vein to enable intravenous drug administration and blood collection during the immunosuppressive period. A schematic overview of the complete reconstruction is