The free vascularised iliac crest graft: an animal model

Abstract

An experimental model has been devised for the study of vascularised bone and physeal grafts. The albino rat is now widely used in microsurgical research, vessels of 0.5 mm diameter are anastomosed with consistent results and growth studies may be completed in a relatively short period. The rat iliac crest is supplied by a paired branch of the abdominal aorta, the deep circumflex iliac artery (DCIA): older texts may refer to this as the iliolumbar artery. Arising I to 2 cm distal to the origin of the renal vessels the DCTA crosses psoas, quadratus lumborum and iliacus, passing beneath the ureter. It penetrates the abdominal wall through a divarication of the inguinal ligament, adjacent to the anterior superior iliac spine. Cutaneous branches supply skin over the lumbar and gluteal regions. Two or 3 branches deep to the inguinal ligament supply bone and muscle of the iliac crest and the crest may be isolated on this pedicle if a cuff of muscle is preserved, usually on the inner aspect. A skin flap is included with the graft to improve anastomotic flow and to allow patency to be monitored. The crest is approached by raising an ellipse of skin on a DCIA pedicle and tracing the vessels proximally. The inguinal ligament is divided and reflected medially, exposing the iliac branches, which are protected in a cuff of muscle whilst the crest is otherwise stripped to periosteum. The abdominal portion of the DCIA is dissected to give a common pedicle of about 1.5 mm. On division of the ilium and the pedicle vessels the graft may be transferred to the femur or upper tibia, with anastomosis to either the superficial epigastric of femoral vessels. This model offers many advantages over the use of larger animal models and with careful microvascular technique flap survival should exceed 90%.