Penile Prosthesis Implantation Treatment & Management

Updated: Aug 31, 2016
  • Author: Richard A Santucci, MD, FACS; Chief Editor: Bradley Fields Schwartz, DO, FACS  more...
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Treatment

Medical Therapy

Nonsurgical treatments for erectile dysfunction (ED), such as vacuum devices, intraurethral alprostadil pellets (MUSE), oral sildenafil (Viagra), and intracavernosal prostaglandin injection, should be attempted prior to penile prosthesis implantation. In the authors' experience, patients in whom conservative treatments have failed tend to be more satisfied with their choice of surgical intervention.

In patients with hypogonadism, long-term androgen replacement can obviate the need for penile implant surgery. Oral or depot testosterone can be administered, and, if sufficient to maintain testosterone level, transdermal patches may be prescribed. At least an annual prostate-specific antigen (PSA) test should be performed because men on testosterone supplementation are at higher risk for developing prostate cancer.

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Surgical Therapy

The criterion standard for erectile surgery is penile prosthesis implantation. However, in the rare patient whose discrete and focal arterial lesion can be identified on arteriography, revascularization procedures may be indicated. Further considerations for optimizing outcome include selecting patients whose etiology is previous pelvic trauma and patients who are young, do not have diabetes, do not smoke, and have no underlying neurologic disease.

Many techniques for the placement of penile prosthesis exist, including infrapubic, penoscrotal, perineal, and subcoronal approaches. The subcoronal approach is suitable only for implantation of semirigid devices. The perineal approach for implantation of semirigid prostheses is seldom used. Only the infrapubic and penoscrotal approaches are suitable for implantation of 3-piece inflatable devices. The infrapubic approach has a distinct advantage over the scrotal approach in the ability to place the reservoir under direct vision. However, in the eyes of the authors and many others, the disadvantages undermine this one advantage. These disadvantages include possible damage to the dorsal penile nerves with accompanying sensory loss, limited exposure of the corpora, and inability to fixate the scrotal pump via this approach.

The authors prefer the penoscrotal approach because it provides very good exposure to the corporal bodies, allows for concomitant repair and excision of Peyronie plaque near the base of the penis, and facilitates the placement of scrotal pumps. Although many techniques exist, they generally follow the same principles. This article describes the authors' technique for penile prosthesis placement via the penoscrotal approach.

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Preoperative Details

Preoperative preparation entails a detailed checklist of items. The patient should be free of infection in the urine, on the skin, or elsewhere. Perioperatively, many infection control measures have been suggested, but few methods have been evaluated carefully in a randomized fashion.

Some surgeons suggest that the patient shower with a surgical scrub the day before and the morning of surgery to decrease skin bacterial colony count. One hour prior to surgery, a wide-spectrum antibiotic, such as cefazolin (Kefzol or Ancef) 1 g IV and gentamicin 80 mg IV, is administered. Oral fluoroquinolones 1-2 hours prior to surgery have been shown to produce excellent corporal tissue levels and to provide excellent coverage. In the operating room, the patient can be anesthetized either with regional or general anesthesia. The authors prefer spinal or general anesthesia, although some do perform this procedure under local anesthesia, usually in patients at high risk for anesthetic complications. Under anesthesia, the patient is shaved at the surgical site and the hairs are removed from the field.

The authors have adopted a rigid regimen of infection control practices that have resulted in some of the lowest published rates of prosthesis infection (national reported range, 0.6-8%). To decrease the chances of airborne infections, only clean laminar flow operating rooms, such as those used for joint replacement procedures, are used. Iodinated preparation solutions (Baxter iodine scrub and iodine preparation solution) are used to scrub and then paint the lower torso, including the abdomen, genitalia, bilateral thighs, and inguinal folds. Next, the bladder is catheterized to drain the urine; then, it is irrigated with antibiotic solutions (bacitracin 50,000 U and gentamicin 160 mg in 1 L NaCl). Finally, a solution of 50% iodine preparation and 50% antibiotic solution is used to irrigate the urethra as the Foley is removed, taking care to prevent iodine from entering the bladder because it is an irritant.

The surgical team scrubs for at least 15 minutes and returns to scrub and prepare the patient for another 15 minutes with iodine scrub and preparation. The patient is draped carefully in the standard surgical fashion. After draping, the surgical team changes their gloves and double gloves. With this precautionary regimen, the authors have significantly reduced the infection rate to 0.4%.

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Intraoperative Details

A 16F caliber Foley catheter is inserted and capped with a catheter plug. A self-retaining circular retractor (eg, Scott retractor by Lone Star Medical Systems) with elastic hooks is placed over the genitalia. A 3-cm incision is made at the penoscrotal junction at the mid raphe and carried down to the superficial/dartos fascia. Once the dartos fascia is divided, the hook elastic retractors are used to hold the surgical field open. The next step is to dissect over, identify, and then avoid the corpus spongiosum by moving laterally to expose the corpora cavernosa on each side of the spongiosum. A small (1-cm) corporotomy incision on the corpora cavernosa is made after placement of 2-0 Vicryl (polyglactin) stay sutures as depicted in the image below. This exposes the corporal spongy tissue.

Exposure of the corpus cavernosum followed by plac Exposure of the corpus cavernosum followed by placement of stay sutures in the walls of the corpus followed by corporotomy in anticipation of placing an intracavernosal rod. (Photograph courtesy of Chirpraya B. Dhabuwala, MD).

A blunt Hegar dilator is used to dilate the spongy tissue of the corpus cavernosa from 8-14 mm proximally and 8-11 mm distally as depicted in the image below. A Dilamezinsert (DMI) instrument is used to measure the corporal length so a prosthetic device of the proper length can be chosen. Meanwhile, throughout the operation, antibiotic solution is misted over the surgical sites and over the instruments at regular intervals and when each anatomical compartment is opened.

Proximal dilation of the corpus with Hegar dilator Proximal dilation of the corpus with Hegar dilator. (Photograph courtesy of Chirpraya B. Dhabuwala, MD)

The appropriate 3-piece prosthesis is selected, the package is opened, and the contents are sprayed copiously with antibiotic solution. The cylinder and pump is checked for integrity, and all air is removed by infusing sodium chloride solution and then back-suctioning to collapse the cylinders. Next, the proximal cylinder is placed gently into the proximal cavernosal body and seated down into its position next to the pubic bone as depicted in the image below.

Seating of the proximal portion of the prosthesis Seating of the proximal portion of the prosthesis into the corpus. (Photograph courtesy of Chirpraya B. Dhabuwala, MD).

The distal half of the cylinder is brought through the distal corporal body with a Furlow inserter. This instrument passes a needle through the glans penis and is designed to avoid the urethra. The needle is removed, and the accompanying thread is used to pull the cylinder snugly against the distal glans (still within the cavernosal body as depicted in the image below. This procedure is repeated for the contralateral side.

Seating the distal portion of the prosthesis into Seating the distal portion of the prosthesis into the distal corpus using the suture attached to the prosthesis. Previously, the suture has been passed out the glans penis using a Furlow inserter. (Photograph courtesy of Chirpraya B. Dhabuwala, MD).

Next, the open corporal bodies (corporotomies) are closed using 2-0 braided dissolvable suture (polyglactin by Vicryl Ethicon), carefully reapproximating the tough tunica albuginea. A P-3 retracting tool is used to push down on and protect the prostheses from the needle when the corpora are being closed. After closure is complete, the tubing from the cylinders is visible coming from inside the corpora and connected to the control pump.

The next consideration is placement of the abdominal reservoir. If the patient has received prior pelvic radiation treatments or has undergone pelvic surgery, placing this through a separate abdominal incision can be prudent. Otherwise, the reservoir can be tunneled from the scrotal area via the external inguinal ring, through the transversalis fascia to place the reservoir into the retropubic space (also called the space of Retzius). Once there, the reservoir is filled to the correct volume (60-100 mL); then, the tubing is brought to the pump, trimmed to length, and connected to the pump. The prosthesis is tested for inflation, deflation, and leaks. It is left in a semirigid state to help tamponade potential bleeding and hold the tissue in the correct shape.

The pump must now be inserted in a scrotal subdartos pouch as depicted in the image below. Using blunt dissection, a subdartos space is created in the anterior dependent area of the scrotum, and the pump is placed there for ease of location and usage. Some have used a nasal speculum to help with this dissection.

Bluntly creating the subdartos pouch, which will h Bluntly creating the subdartos pouch, which will house the pump. (Photograph courtesy of Chirpraya B. Dhabuwala, MD).

If necessary, the process of penile molding can take place at this juncture for patients with asymmetric phallus and Peyronie plaque. In the inflated state, rubber shods are clamped on the prosthesis tubing to take up the extra pressure that would compromise the control pump valves. The surgeon can gently torque and bend the asymmetric penis into a more symmetric shape.

Finally, any light bleeding is detected and electrocauterized. The scrotal/dartos fascia is closed in 2 layers with medium polyglactin (Vicryl) sutures, and the skin is closed with a running subcuticular fine dissolvable suture. Then, the patient is cleaned, the potentially irritating iodine paint is washed away, and the Foley catheter is connected to a dependent drainage bag.

Some key items regarding operative techniques should be remembered. Accurate measurement of the corporal bodies is key to good device performance. [8] Isotonic solution should be used in the device because silicone is semipermeable over time. The phenomenon of autoinflation, which is inflation of the prosthesis caused by differential pressure changes without manually pumping the device, can be inconvenient. It is largely avoided by placing the reservoir in the retropubic space, by performing back-pressure tests when filling the reservoir to ensure the correct volume is added, and by keeping the device deflated and the reservoir full when the pseudocapsule is forming around the reservoir.

Frequently, the authors purposely leave 5-10 mL of the stated reservoir capacity unfilled. This allows for adequate filling of the prosthesis without having to worry about differential pressure. The new Mentor devices with a reservoir valve lockout have proven to be very successful in preventing autoinflation.

Finally, the companies that make penile prostheses often make their technical and sales representatives available to assist in the operating room. This can be particularly useful for surgeons who do not routinely place these devices.

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Postoperative Details

The next morning, the Foley catheter is removed, the prosthesis is partially deflated, and the patient is discharged home with a follow-up visit in the office for further instructions and oral antibiotics for approximately 14 days.

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Follow-up

The patient is instructed to refrain from sexual activity for 6 weeks. After 6 weeks, the patient is instructed on the usage of the inflatable penile prosthesis.

For excellent patient education resources, visit eMedicineHealth's Men's Health Center. Also, see eMedicineHealth's patient education articles The Male Anatomy, Impotence/Erectile Dysfunction, and Erectile Dysfunction FAQs.

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Complications

After the prosthesis is placed, patients may experience modest penile shortening in the range of about 2 cm. This must be discussed with the patient and partner prior to any surgical intervention. Patients also should be aware that they may never achieve their most youthful length and girth due to underlying pathology such as fibrosis and plaque formation. Other issues that should be addressed include possible erosion of the device over time and the possibility of implant infection despite careful preoperative preventive means. An average infection rate ranges from 2%-4% over a 2-year period with a national wider range of 0.6%-8%. Most infections become evident within the first year and are due to seeding during implantation.

Some bacterial species, such as Staphylococcus epidermidis, can lie dormant for as long as 2 years before causing clinical signs of infection. Risk factors for infection include prolonged hospital stay, diabetes mellitus, concomitant surgical procedures such as artificial sphincter implantation and circumcision, spinal cord injury, paraplegia, and the use of additional foreign bodies during implantation. None of these conditions or circumstances are contraindications to implantation but rather emphasize increased attention to infection prevention. Another potential complication is mechanical failure, which can occur with use and may require repeat surgery for revision or replacement. Overall, reoperation rate for mechanical failure is about 5% for the life of the prosthesis (5-10 y).

Intraoperative challenges occur and require good problem-solving skills and creativity. Most difficulties concern prosthesis cylinder placement. Inadequate dilation of the corporal bodies can cause prosthesis migration, unnatural-looking erections, and pain, among other problems.

Corporal crossover due to the thinness of the distal corporal septum that divides the corporal bodies can occur. Vigorous dilation can cause a crossover injury where the prosthesis cylinders occupy the same corporal body. This is most likely due to not dilating in a lateral, but rather in a medial, fashion. If recognized early, it can be corrected by redilating but maintaining a lateral course and keeping another dilator in the contralateral corporal body. Recognizing this problem intraoperatively is important to avoid penile curvature, pain upon inflation, and unnatural-looking erections.

Penile corporal fibrosis is a common finding among patients who have undergone intracavernosal injection therapy, those with history of priapism or Peyronie disease, and those with penile trauma or reimplantation of prosthesis after infection. Multiple dilations are necessary, usually starting with blunt-tipped Metzenbaum scissors to gently spread the corpora. Other dilators, such as Hegar, Brooks, or DMI, may be used in conjunction to carefully and deliberately dilate/dissect the fibrosed corpora. Sometimes, additional incisions must be made, including distal corporotomies to dilate under direct vision and dissect away fibrosed tissue.

Montague and Angermeir (2003) reported on a transverse penoscrotal approach, which they used in men with severe corporeal fibrosis in whom scarring was due to ischemic priapism or removal of an infected prosthesis. An inverted "T" incision was made, exposing almost the entire corpus cavernosum on each side. They found that this incision obviates blind dilation, making the dissection of the corporeal bed much safer.

Pathak et al (2005) also described a novel approach whereby a rectus fascia graft was harvested for corporeal reconstruction. Augmentation of the tunica with autologous rectus fascia and implantation of a penile prosthesis was successfully completed in 15 patients with severe scarring. No evidence of graft infection or erosion was noted after a mean follow-up of 18 months. [9]

In certain instances, defects in the tunica albuginea require patching with material such as Gore-Tex or cadaveric tissue. When extensive fibrosis that may jeopardize the operation is encountered, a viable consideration is to abandon the very fibrosed side and place a single cylinder on the contralateral side. In general, when extensive nondilatable corporal fibrosis is encountered, downsizing the inflatable prosthesis device is important. Certain manufacturers offer a line of prosthetics that have limited lateral girth and may help in this application (eg, AMS 700CXM).

Proximal corporal perforation can occur after vigorous proximal dilation, especially in the presence of extensive fibrosis. To avoid this, careful initial sharp dissection with blunt-tip Metzenbaum scissors should be attempted. The corporotomy incision may require lengthening to achieve adequate exposure. Should perforation occur, it can be recognized with differential measurements of the corporal length greater than 1 cm, feeling of a sudden "give" during the dilation process, and inadequate dilator seating compared with the contralateral side.

Correction of proximal perforation can include securing prosthesis tubing sheath or rear tip extender to the tunica albuginea. Over time, the perforation heals because of scar formation around the cylinder. A better alternative is repair by creating a wind-sock patch with Gore-Tex, Dacron, or autologous/cadaveric fascia. By placing this wind-sock, the defect is covered and fixed in place with nondissolvable suture, and it allows for good seating of the rear-tip of the cylinder.

Urethral perforation is another possible complication of extensive fibrosis. In the authors' institution, the placement of the prosthesis is abandoned and healing is awaited after any necessary repair prior to another attempt after 4-6 weeks. Other surgeons may choose to modify their operation, including stenting the urethra and draining the bladder with Foley catheter and placing a single cylinder on the unaffected side. This injury is usually recognized intraoperatively by blood in the urine, blood at the meatal tip, and irrigation fluid exiting the urethra.

Glans bowing can occur when the prosthesis is inadequately sized. This ventral deflection of the glans is commonly called the "SST deformity" after the Concorde supersonic transport aircraft. The Concorde's nose-cone tips downward during takeoffs and landings to provide pilots better visibility, but urologists have adopted this metaphor for distal glanular penile curvature. SST deformity should be checked intraoperatively to ensure adequate dilation of the distal corporal bodies. If the defect does exist, further dilations may be necessary, and resizing the prosthesis may be in order. In rare instances, a dorsal plication procedure may be necessary.

An important topic that should be addressed is the concept of salvage implantation as pioneered by Mulcahy. [10] He describes removing infected penile implants, cleansing the wound with a series of antiseptic solutions, and then placing a new prosthesis in the same procedure. During the cleansing and irrigation process, the biofilm or slime made by the microorganism (eg, staphylococcal bacteria) should be washed from the newly formed pseudocapsule.

The pseudocapsule is a fibrous sheath that will form naturally around the inflatable prosthesis as the healing process begins. Once formed, it has a very poor blood supply and becomes a barrier to intravenous antibiotics. Bacteria can grow in this protected zone around the prosthesis and can begin to form colonies with their associated biofilm. The mechanical washing with antiseptics, as Mulcahy describes, is the only feasible way to attempt to eradicate an infectious process during a salvage procedure.

His irrigation solution includes a specific protocol of kanamycin-bacitracin, hydrogen peroxide, and iodine solution, followed by pressure washing with vancomycin and gentamicin. This sequence is then repeated. Mulcahy reports about an 80% success rate with his salvage technique. However, he warns that certain conditions make salvage success unlikely. These conditions include infection with a virulent organism and patients with a serious systemic illness (eg, septicemia, diabetic ketoacidosis) or necrotizing infections, including those with frank purulent drainage.

In addition, a mini-salvage procedure, which entails a curtailed version of Mulcahy's irrigation protocol, is espoused as standard practice by many urologists in replacement of uninfected prostheses, as biofilm formation is documented to occur on virtually all explanted prostheses. This biofilm is believed to be responsible for the higher rate of infection seen with replacement, even if the original device was clinically infection-free.

In the care of a skilled and experienced surgeon, most prostheses are placed without difficulty and function well for many years.

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Outcome and Prognosis

Generally, the authors' experience at Wayne State University Department of Urology is that the vast majority of patients in whom conservative therapy has failed and who subsequently underwent a penile prosthesis implantation are very satisfied with inflatable penile prostheses. Of men who have undergone this procedure, 95% are happy about their decision to have surgery. Patient satisfaction with surgery is bolstered by supportive staff and low infection and malfunction rates.

National multicenter studies show similar satisfaction rates, ranging from 69%-89%. Using validated questionnaires, Akin-Olugbade et al (2006) reported that predictors of lower satisfaction included Peyronie disease, a body mass index of greater than 30 kg/m2, and previous radical prostatectomy. [11] Of all modes of ED treatment, surgical therapy yielded the highest satisfaction rates. Interestingly, even despite good mechanical function, the satisfaction rating of the patients’ sexual partners is comparatively lower (60%-70%). Some experts attribute this to a psychological factor (ie, unrealistic expectation of the implantation). Jarow et al (1996) recommended counseling the patient and partner on realistic goals of implants and informing them that an implant may not be as satisfying as a natural erection. [12]

A study by Carvalheira et al that interviewed 47 men who underwent penile prosthesis implantation found that the majority of men (79%) reported to be satisfied with penile prosthesis implantation. The four main themes for men’s satisfaction were psychological factors (reported 54 times), improvement of sexual functions (reported 54 times), relationship factors (reported 11 times), and improvement in urinary function (reported 3 times). [13]

On average, patients may wear out their prosthesis in 4-8 years. Revisions become more common as time passes. Some of the older patients have undergone as many as 4 revisions over 2 decades of use. [14]

Goldstein et al (1997), studying the 3-piece Mentor Alpha 1 prosthesis in multicenter trials, reveals a Kaplan-Meier actuarial device survival rate of 98% at 12 months, 93% at 24 months, and 85% at 36 months. [15] Dhar et al (2006) studied the AMS 700CX/CXM and found that the implant mechanical survival rate was 81% after a median follow-up of 91.5 months. [16] Lux et al (2007) reported on 147 patients with newest version of the AMS Ambicor 2-piece device, and only one implant had a mechanical failure over a mean follow-up of 38 months. [17]

A prospective study by Rolle et al found that penile length restoration with the use of the “sliding” technique represents an effective option for end-stage Peyronie's disease associated with erectile dysfunction and severe shortening of the shaft. [18]

With steady improvements regarding prosthesis material and construction, long-term survival of the modern implants shows promise.

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Future and Controversies

The popularity and success of sildenafil (Viagra) and it competitors, vardenafil (Levitra) and tadalafil (Cialis), has brought to light the prevalence of erectile dysfunction (ED). Men who would have ignored their ED problem in the past are now realizing the potential help available.

Along with development of surgical/prosthesis improvements, new medical agents are emerging for evaluation. Among them is apomorphine, a direct central dopamine receptor agonist. Used for parkinsonism in the past, it has a lasting side effect of eliciting durable erections in small studies of patients. It has a sublingual formulation, which is currently under clinical investigation, but time will tell if it proves as successful as the phosphodiesterase-5 inhibitors.

When men with ED begin trying conservative therapy (which fails in some), the authors believe that these patients will eventually seek surgical options such as inflatable penile prostheses. With this new influx, urologists may witness a second wave of patients seeking surgical correction for their impotence.

The future holds more promise. Currently, Mentor 3-piece inflatable prostheses come equipped with a lockout valve designed to prevent autoinflation. Initial studies have shown a decreased incidence of autoinflation, from 11% to 2%. [19] The remaining 2% incidence was attributed mainly due to improper usage. The newest AMS 700 devices now also incorporate a lockout mechanism, and anecdotal reports have been positive.

Other mechanical improvements include buttressing of the sites most prone to breakage, notably the tubing junctions. The incorporation of rear-tip extenders that lock onto the prosthesis cylinders are one of the newest improvements for both the Mentor and AMS implants. This innovation is of particular value when explanting or replacing a device, since rear-tip extenders commonly slip off the main body of the cylinder and can be difficult to retrieve from the proximal corpora. Retrieving these old rear-tip extenders is critical before implanting a new device in order to minimize infection. The new locking rear-tip extenders appear promising in avoiding this problem.

Prostheses impregnated with antibiotics, such as the InhibiZone coating (rifampin and minocycline hydrochloride) used in the AMS 700 series, is proving to significantly decrease the incidence of postoperative infection. [3, 20] Similarly, the new Mentor Titan 3-piece device is coated with polyvinylpyrrolidone, a hydrophilic substance that decreases bacterial adherence and absorbs topical antibiotics. This innovation has also been shown to decrease the incidence of infection. [21] Another avenue being explored to increase satisfaction with penile prostheses is dealing with "cold glans," which is expected because the prosthesis does not affect glans engorgement. Topical alprostadil cream is showing some preliminary promise as an adjunct to penile prosthesis in increasing erectile satisfaction by increasing engorgement of the glans. [22]

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