Clinical Conditions

Penile Implant (Prosthesis) Surgery has undergone significant changes over the course of the 3 decades since its introduction and now represents a safe and effective means of treating men with ED.

Patient Selection

Patients who attempt but dislike or fail to achieve satisfactory results with pills, suppositories, vacuum devices or injections, are counseled about penile implant surgery if they are interested in pursuing further treatment. It is important that all patients receive appropriate preoperative education concerning risks and benefits of the procedure. This discussion should cover the operation, the frequency and ramifications of potential complications and a discussion regarding appropriate expectations following surgery. The patients are advised that the prosthesis will allow them to achieve a rigid erection on demand and will likely have little effect on their libido and will NOT lengthen their penis.

Prosthesis Selection

Prostheses can be divided into two main categories, malleable (also known as non-hydraulic or semi-rigid) and inflatable (also referred to as hydraulic). The latter can be subdivided into 2-piece and 3-piece devices depending upon the location of the fluid used for inflation. At the Sexual Medicine Program at The New York Presbyterian Hospital, 3-piece models are the most commonly implanted, however, 2-piece devices are useful for certain patient populations. Malleable models are only occasionally placed in this era, given the recent data regarding the excellent complication/longevity profile of inflatable devices. Malleable prostheses should be avoided in patients at high risk of erectile body or urethral erosion such as spinal cord injured patients and diabetics, as well as men who have had penile irradiation.

Malleable devices have an outer shell with a central core of metal or plastic. These prostheses are paired solid devices implanted in the erectile bodies that produce constant penile rigidity. The primary advantage of these devices is their ease of implantation while the disadvantages include a constantly rigid penis that resembles neither normal erection nor flaccidity, difficulty with concealment, and an increased risk for device erosion. Three such devices exist at this time (AMS Malleable 650, Mentor Acu-Form prosthesis and TIMM Medical Dura-II devices).

Historically, inflatable devices were of 3 varieties, self-contained (which are now out of production), 2-piece, and 3-piece devices. The AMS 2-piece device (Ambicor), the only 2-piece in production at present, consists of cylinders that are pre-connected to a ball-shaped pump, which is seated within the scrotum. Compression of the pump results in transfer of fluid from the back part of the cylinders into the middle portion resulting in rigidity. The deflation mechanism involves bending of the penis in mid-shaft resulting in fluid being returned to the back section. We have found that informing patients that the distal ends of the device are solid improves patient satisfaction postoperatively.

Between the two major companies, there are five different 3-piece devices available to address most implant situations. Three-piece inflatable implants have paired cylinders, a small scrotal pump, and a large-volume fluid reservoir (which is placed behind the abdominal wall muscles). AMS manufactures three devices of this type: the AMS 700CX prosthesis, AMS 700CXM device, and AMS Ultrex device. The cylinders of this latter 3-piece implant provide both girth and length expansion. Mentor manufactures two 3-piece inflatable prostheses, the Alpha I and the Alpha I Narrow Base devices, a small-diameter version useful for implantation in men with scarred penises. Recently, Mentor introduced a lock-out valve on their reservoirs to circumvent the annoying post-operative complication of auto-inflation. Our initial experience with this modification has been very positive.

Both companies are working conscientiously to develop a device that is coated with an anti-microbial or protectant. AMS has introduced the 700CX device coated with an antibiotic mixture (rifampin/minocycline) (labeled Inhibizone™). Mentor will soon release its anti-adherence coated device (labeled Titan™) having obtained recent FDA approval. It is unclear at this time if these coatings truly reduce the incidence of infection in the general population of penile implant patients. The ideal penile prosthesis will permit a man to control when he has an erection and will allow penile flaccidity and erection that approximate, as closely as possible, a natural erection. While the currently available 2-piece device approaches this ideal state, it is my opinion that the 3-piece inflatable prostheses are more representative of the natural erect and flaccid profiles of the penis. For this reason, it is my practice to place a 3-piece device where possible. We routinely utilize the Mentor Alpha-1 device, however, other centers use the AMS 3-piece with excellent results.

There are a number of populations in which we consider implanting the AMS Ambicor 2-piece device. Other authorities utilize 3-piece devices in some of these populations with excellent safety and satisfaction. These populations include (i) Patients who have had radical cystoprostatectomy (bladder removal) surgery; (ii) Patients who have had renal transplant surgery or are about to receive such a transplant (iii) Certain patients who have had radical prostatectomy; (iv) Patients who have had bilateral inguinal hernia surgery (especially with mesh) and (v) Spinal cord injured patients who desire penile implant surgery for erectile dysfunction as well as permitting the application of a condom catheter.

The pros and cons of the 2 and 3-piece devices should be explained to the patient to enable him to make a more informed choice. We insist on all patients reading device literature and viewing a device video, as well as the routine lengthy counseling session prior to committing to the procedure. Ensuring that the patient has realistic expectations prior to proceeding with implant surgery is essential to ensuring high postoperative satisfaction profiles, specifically discussing infection rates (2-3%), rates of re-operation (15%) and the lack of penile length increase with penile prosthesis surgery. While malleable devices have some perceived advantages (decreased mechanical breakdown) and true differences such as ease of placement and lower cost, this center utilizes inflatable devices in almost all patients because of the excellent rigidity and flaccidity profiles of these devices.

Complications

Post-operative complications of penile implant surgery are not common and include but are not limited to implant infection, component failure, device erosion, device migration, sizing problems, and auto-inflation. Infection occurs in approximately 2-3% of primary (first time) implant surgeries. Infection and subsequent device removal may result in penile scaring and loss of penile length, which may lead to the inability to perform any further implant surgery. Following implantation, the time frame for the presentation of infection will vary depending on the bacteria involved. Infections with more virulent and aggressive bacteria will usually present within the first few days to weeks after surgery (fever, pain, and swelling), but low-grade infection may not present for a year after surgery. When infection of the prosthesis is diagnosed the standard treatment is the removal of the entire prosthesis and re-implantation of another device several months later. In an effort to prevent penile length loss and a difficult re-implantation procedure, prosthesis salvage has been proposed and preliminary results using this approach have been very encouraging, with up to 80% of salvage patients keeping their secondary implant.

While erosion of a prosthesis component may or may not be associated with infection, it has been our approach to treat prosthetic erosion in the same manner as treating an infected prosthesis. Re-operation rates are approximately 15% at the 10-year time-point after the initial operation, thus, approximately 85% of men still have their original implant 10 years after the implant surgery.

Satisfaction

Patient satisfaction is a complicated issue and is related to factors as diverse as degree of postoperative pain/swelling, postoperative complications, concealability, cosmetic outcome, implant function, ease of use and partner acceptance. It is clear that penile implants offer the patient a very high level of satisfaction when compared to other forms of ED treatment and do so because of their spontaneity, consistency, and rigidity. We believe that excellent preoperative counseling to ensure that the patient has realistic expectations is essential to a satisfactory outcome. We inform our patients that penile prostheses do ONE thing and that is to increase hardness of the shaft of the penis; that they do not routinely lengthen the penis.

Penile prosthesis implantation has the highest satisfaction rates of all treatment options for erectile dysfunction according to published reports. In one study 89% of the men and 70% of their partners were satisfied. Pain, appearance, and the need for repeat operation were factors resulting in decreased satisfaction. In another study 85% of the men and 76% of their partners were satisfied. In a study comparing penile prosthesis implantation with penile injection therapy, with similar follow-up, 70% of penile prosthesis recipients reported having sex on a regular basis, whereas only 41% of penile injection patients were still sexually active.

In a prospectively conducted study of patient satisfaction following penile prosthesis surgery, Dr. Mulhall evaluated patients undergoing first-time penile prosthesis surgery. Patients completed the satisfaction questionnaires preoperatively and at 3, 6, and 12 months postoperatively. Postoperative satisfaction scores increased as time passed with these scores being highest (greatest satisfaction) between 6 and 12 months after surgery.

Reading

  1. Furlow WL et al: Implantation of Model AMS 700 penile prosthesis. Journal of Urology 139:741-742.1988.
  2. Wilson SK et al. Comparison of mechanical reliability of original and enhanced Mentor Alpha I penile prosthesis. Journal of Urology, 715-8.1999.
  3. Montorsi F et al. AMS three-piece inflatable implants for erectile dysfunction: a long-term multi-institutional study in 200 consecutive patients. European Urology, 37:50-55.2000.
  4. Carson CC. Penile prosthesis implantation in the treatment of Peyronie's disease. International Journal Of Impotence Research, 10:125-8.1998.
  5. Daitch JA et al. Long-term mechanical reliability of AMS 700 series inflatable penile prostheses: Comparison of CX/CXM and Ultrex cylinders. Journal of Urology, 158:1400.1997.
  6. Goldstein I et al. Safety and efficacy outcome of mentor alpha-1 inflatable penile prosthesis implantation for impotence treatment. Journal of Urology, 157:833.1997.
  7. Govier FE et al. Mechanical reliability, surgical complications, and patient and partner satisfaction of the modern three-piece inflatable penile prosthesis. Urology 52:282.1998.
  8. McLaren RH et al. Patient and partner satisfaction with the AMS 700 penile prosthesis. Journal of Urology 147:62-65.1992.
  9. Mulhall JP et al. Serial assessment of efficacy and satisfaction profiles following penile prosthesis insertion. Journal of Urology 165(5):1042A, 2001.