Comparative histological and functional controlled analysis of tubularized incised plate urethroplasty with and without dorsal inlay graft: A preliminary experimental study in rabbits

Purpose: We analyzed the histological and functional characteristics of the tubularized incised plate vs dorsal inlay graft urethroplasty in an experimental rabbit model. Materials and Methods: A total of 24 New Zealand male rabbits were randomly allocated into 4 groups, including sham operation, urethroplasty, tubularized incised plate urethroplasty and dorsal inlay graft urethroplasty. In the urethroplasty group the anterior urethral wall was half excised and the dorsal aspect was tubularized. In the tubularized incised plate group the same steps were followed but tubularization followed a longitudinal midline incision in the dorsal wall. In the dorsal inlay graft group the defect created by the dorsal incision was covered with an inner preputial graft. The animals were sacrificed at 4 and 8 weeks, respectively. The penis was immediately harvested for standardized passive flowmetry and subsequently fixed for histological staining. Results: The grafts took in all animals. The tubularized incised plate defect was bridged by urothelium while in the dorsal inlay graft group the preputial graft kept its original histological characteristics. There was a significant decrease in average flow in the urethroplasty group (1.6 ml per second) compared to that in the sham operated group (3.4 ml per second) and to the other groups (p <0.05). However, no significant difference in average flow was found for the tubularized incised plate and dorsal inlay graft groups (2.4 and 2.2 ml per second, respectively, p = 0.7). Conclusions: In this short-term rabbit model dorsal inlay graft urethroplasty was feasible with good graft take and integration. Simple tubularization of a reduced urethral plate led to significantly decreased flow. Incision of the reduced plate with or without grafting improved the average flow. Findings in this experimental model do not support the superiority of dorsal inlay graft urethroplasty over tubularized incised plate urethroplasty in terms of urethral flow dynamics.