Use of three-phase bone scans and SPET in the follow-up of patients with allogenic vascularized femur transplants.

The vascularized allotransplantation of femoral diaphyses under immunosuppression is a novel approach in orthopaedic surgery. To evaluate which method provides the best information about microvascularity and viability of the transplant, we compared different diagnostic approaches used in transplant surgery. Three patients were investigated four times over a period of 1 month (on days 2, 7, 15 and 30 post-transplantation) and 6 and 12 months later with planar 99Tcm-MDP three-phase bone scintigraphy and SPET. The results were compared with duplex sonography, angiography and intraoperative biopsies. Rejection and thrombosis of the transplant were associated with decreased or missing perfusion detected by duplex sonography, angiography and blood pool scintigraphy. In these cases, late bone scans showed reduced or absent bone metabolism while biopsy revealed necrotic bone tissue. In cases without complications, blood pool scans revealed hyperaemia of the graft indicating excellent perfusion and patency of vascular anastomoses and transplant vessels. Late bone scans demonstrated increased bone metabolism. The corresponding biopsies showed viable bone cells. We conclude that bone scintigraphy is a valuable diagnostic tool in vascularized femur allotransplantation, since it provides reliable information on both viability and perfusion of the transplant within a single non-invasive investigation.