Spontaneous penile tumescence after penile prosthesis implantation has been previously reported as sporadically occurring during implant surgery. This study aims at systematically preserving residual erectile function, by the preservation of the patients' spontaneous penile tumescence by systematically sparing cavernous tissue during penile prosthesis implantation.

Patients undergoing the cavernous tissue sparing penile implant procedure will be injected intraoperatively with 40µg alprostadil, a prostaglandin E1 agonist intracorporal injection (ICI). The procedure will begin as soon as maximal tumescence is attained.

In the cavernous sparing group, corporal dilation will be done solely with a size 8 dilator. The insertion of the dilator will be carefully inserted in what we call the path of least resistance. To determine the path of least resistance, the corporotomy is spread apart by pulling on previously set stay sutures. The path of least resistance is the plane with maximum outflow of blood from the intraoperatively pharmaceutically dilated and blood filled corpora cavernosa. This plane can also be anticipated with a preoperative penile duplex.

Inclusion Criteria:

• Erectile dysfunction not amenable to treatment by approved medical therapy

Exclusion Criteria:

• Erectile dysfunction amenable to treatment by approved medical therapy