Dolph Houben

163 New surgical technique of whole joint VCA 8 vascular supply to be a branch of the medial circumflex artery [17] . In addition, the gracilis is supplied by small branches arising from the femoral and saphenous arteries. Based upon the dominant vessels, we raised a wide and thin muscle flap, approximately 180mm long, 90mm wide and 10mm thick. When rotated, the flap covered the entire allogenic knee transplant. This provides both a deeper layer of transplant cover but should also stimulate some autologous angiogenesis on the surface of the allotransplant. Surgical outcome Three female recipients were operated at a mean age of 11 weeks with a mean weight of 26.6kg. All animals recovered extremely well after approximately 10 hours of surgery. They were able to ambulate on three feet for the first postoperative days and able to tiptoe on their operated leg. Immunosuppression levels were in the therapeutic range for the first two weeks (mean tacrolimus: 8.36 ng/mL, mycophenolate: 1.23 mcg/mL). In the first 4 days after surgery all animals developed progressively severe seromas until the point that they were not able to ambulate, but no animals were clinically showing signs of infection or rejection at that moment and remained good appetite. Daily observation, monitoring, and administration of antibiotics and analgesics were performed in close collaboration with comparative medicine. Over time, the seromas did not resolve spontaneously, as we have observed in our previous tibia defect models. The severity of the seromas and inability to walk resulted in pressure wounds on the medial malleolus and subsequent infection of the seromata. In collaboration with comparative medicine and in accordance with the Institutional Animal Care and Use Committee (IACUC) guidelines, the animals were sacrificed at the end of the second week after transplantation according to the sacrifice protocol. Evaluation of available data All vascular pedicles were patent at the time of sacrifice, confirmed with microangiography (Fig. 4) and demonstration of contrast agent in the tissue seen both on gross visual inspection and in histologic slides (Fig.5.1). Histologic evaluation of the allogenic vessels showed no signs of intima hyperplasia, frequently observed in more chronic transplant rejection (Fig. 5.1). Osteocyte, cartilage, and epiphyseal viability was maintained (Fig. 6). However, widespread infiltration of leukocytes and lymphocytes was found in all specimens (Fig. 7). Differential leucocyte counts over the brief survival period revealed an increase in white blood cells and higher percentages of neutrophils 2 weeks following transplantation, and at time of sacrifice due to the infected seromas (Fig. 7). Prior to surgery the median passive knee range of motion was 40 degrees, after two weeks 32.77 degrees, and at time of sacrifice 37.5 degrees.