Tunica vaginalis for correcting penile chordee in a rabbit model: Is therea difference in flap versus graft?

Purpose: We compared tunica vaginalis applied as a flap versus a graft for covering defects in the ventral tunica albuginea in a rabbit model. Materials and Methods: We used 18 New Zealand White rabbits in the study. T he urethra was mobilized off of the corpus cavernosum. A defect was created in the ventral aspect of the tunica albuginea by excising a 1 X 0.5 cm. re ctangular area. The defect was covered by the testicular surface of tunica vaginalis as a vascularized flap in 9 animals and as a graft in 9. At 2, 6 and 12-week intervals 3 animals per group were sacrificed. Transverse secti ons of the penis at the repair site were stained with hematoxylin and eosin , and Masson's trichrome for microscopy. Results: Autopsy revealed no contracture in any of the tunica vaginalis fla ps. In contrast, the tunica vaginalis grafts had contracted by a mean of 22 % (range 20% to 25%) at 2, 38% (range 30% to 44%) at 6 and 42% (range 38% t o 48%) at 12 weeks. Microscopic examination of the tunica vaginalis flaps s howed evidence of an intact blood supply and viable cremasteric muscle laye r but no evidence of necrosis. Collagen remodeling and maturation was noted at 12 weeks. In tunica vaginalis grafts there was evidence of necrosis of all tunica vaginalis layers at 2 weeks with granulation tissue and active f ibrosis at the periphery. At 6 and 12 weeks most necrotic tissue was replac ed by fibrosis. Osseous metaplasia was identified in 1 graft at 12 weeks. Conclusions: The optimal use of tunica vaginalis for correction of chordee is as a flap rather than as a free graft. Grafts were associated with signi ficant necrosis and contracture, of which neither was associated with flaps .