The Evolution of Artificial Sphincter Cuff in Growing Animals

Abstract

An animal model was developed to simulate the effect of implantation of artificial sphincter cuff on the urethra in children. The study was conducted on 28 pigs, 15 castrated males, four uncastrated males and nine females, divided into four groups: control unoperated, and three operated groups. Group I contained young piglets (castrated males, uncastrated males and females), group II contained adult animals and group III contained sham operated animals. An AS 800 belt occlusion cuff was implanted in the deflated state distal to the bladder neck around the urethra in the young and adult groups, while no sphincter was implanted in the sham group. Neither primary nor secondary activation was done. The pigs were followed for a period of six to eight weeks and then sacrificed. The morphological and histological observations on the effects of the artificial sphincter cuff on the underlying urethral tissue showed significant transmural atrophy of the urethral and prostatic segment underlying the cuff in the young growing castrated and uncastrated male group with mild changes in the young female group. Bladder rupture occurred in three uncastrated males. There were no changes encountered in the adult or sham operated groups. Variable degrees of upper tract changes and renal deterioration were seen in the young group. These changes occurred mainly in the male piglets while a lesser degree occurred in the female piglets. No changes were demonstrated in the adult and sham groups. This study suggests the possibility of similar changes occurring in young male children who have undergone artificial sphincter implantation. (J. Urol., 140:632–636, 1988)