The penile flap in the rat: description and autotransplantation

Considering both its unique structural and functional properties, the reconstruction of the penis is still a challenging problem in reconstructive surgery. Reconstruction may be required in many situations, including traumas, congenital abnormalities, and female-to-male transsexual surgery. Currently, the only natural reconstructive method for the penis is its microvascular reattachment in amputation cases. In all other situations, and in nonreplantable amputations, there is no alternative but to reconstruct the penis using autologous tissues to create the most similar substitute, hoping for a possible allogeneic transplantation in the future. There are many unresolved issues and unanswered questions related to functional recovery after replantation of the penis. In this study, to overcome these drawbacks and to guide and show the feasibility of allogeneic transplantation of the penis in humans in the future, we describe a penile composite tissue flap based on the internal pudendal artery and its autotransplantation in an economical animal species. Fifty adult male Sprague-Dawley rats weighing 400 to 500 g were used. In 20 rats, the vascular anatomy of the male perineal region was determined by anatomic dissections. Based on this anatomic study, the penile composite flap was created based on the internal pudendal vessels. In 10 rats, the penile flap was raised as an island flap based on its vascular pedicle and replaced in situ. In 10 rats, distant flap transfer was accomplished to determine the feasibility of the flap being transferred as a free flap and to demonstrate the viability of the flap components in a heterotopic region. For this purpose, the flap was transferred to the groin region performing anastomoses between internal pudendal vessels and superficial epigastric vessels. In the control group (n=10), while the same surgical procedure was performed, the flap was transferred to the groin region but no anastomosis was performed. The procedure required approximately 3 to 4 hours of operating time in the free flap group. Five of the animals died in the early postoperative days, while all others survived. Direct observation and microangiography were used to assess the viability of the flaps. On the basis of direct observation on the seventh postoperative day, all the pedicled flaps survived completely. In the free-flap group, all but 1 of the vascularized flaps showed complete survival, whereas all the nonvascularized flaps completely necrosed. The authors conclude that the penile flap of the rat offers the following advantages: (1) the composite tissue flap is harvested from a small animal species, (2) the flap is an exact representation of the clinical original penile composition, (3) it can be transferred as a free flap without the need for an isogeneic animal, (4) the vascular pedicle is consistent and allows for microvascular anastomoses. The flap will provide a means for future physiological studies, especially for replantation cases. The feasible autotransplantation of the penile flap with successful results will also guide researchers towards the future allogeneic transfer of the penis in humans.