Transurethral implantation of silicone polymer for stress incontinence: evaluation of a porcine model and mechanism of action in vivo.

OBJECTIVE

To evaluate the anatomical location, histological appearances and mechanism of action of sili-cone polymer (Macroplastique(R)) after transurethral implantation.

MATERIALS AND

METHODS

An in vivo pig model was developed to investigate the organization of Macroplastique 6 weeks after injection. The results were compared with the immediate appearance of injected Macroplastique in a surgical training device (using isolated pig urethrae) and with the histological appearances of Macroplastique in an explanted human specimen.

RESULTS

Macroplastique was subserosal in all specimens; it provoked a marked foreign-body inflammatory reaction, producing firm nodules 6 weeks after implantation. The histological appearances in the in vivo pig model and the human specimen were indistinguishable.

CONCLUSIONS

These findings indicate that the mechanism of action of Macroplastique is to augment pressure transmission to the proximal urethra by producing focal but firm expansion of periurethral tissues.