What is a penile prosthesis?
A penile prosthesis is an artificial device that when placed in the penis allows a man to have an erection. The development and use of penile prostheses began in the 1970s. Since then, revisions and modifications in the prostheses have improved the satisfaction rate and the mechanical durability of the device. The first prosthesis developed was a "rigid" prosthesis. A rigid cylinder was placed into each of the corpora cavernosa. Each cylinder had a fixed length and girth and remained "erect" at all times. The limiting factor was the inability to conceal one's penis. The next type of prosthesis developed was the "semirigid" prosthesis (Figure 10). The semirigid prosthesis cylinder has a flexible metal coil in the center that is surrounded by silicone. This prosthesis also has a fixed length and girth, but unlike the rigid prosthesis, it can be bent down to provide for concealment. The most commonly used prostheses are the inflatable prostheses, which vary from self-contained inflatable prostheses to multipart inflatable prostheses. American Medical Systems makes an inflatable prosthesis that consists of only two cylinders (Figure 10) that contain a pump at their tips. When placed into the corpora of the penis, the pump lies in the glans. Gentle squeezing of the glans activates the pump, which transfers fluid from one compartment of the cylinder to another. This transferring of the fluid creates the rigidity. To deflate the prosthesis the penis is bent over one's hand with gentle pressure on the corpora; this drains the fluid back into the other compartment of the cylinder. Although this prosthesis is simple to use, the main drawback is that it can provide limited girth. The more commonly used inflatable prostheses are the multipart inflatable prostheses, of which there are two types: the two-piece units, which are composed of the two cylinders and a combined pump and reservoir in the scrotum (Figure 11), and the three-piece units, which are composed of the two cylinders, a scrotal pump, and a separate reservoir that is placed in the pelvis (Figure 12).
These prostheses are made by two companies, American Medical Systems (Minneapolis, MN) and Mentor Urology (Santa Barbara, CA). The advantage of the three-piece unit is that it allows for the maximal amount of fluid transfer given the larger reservoir size. Also, when placed, the device and its tubing are completely concealed, so one is able to void in the locker room without anyone knowing that the multipart prosthesis is present.
Placement of a penile prosthesis requires extensive patient and partner discussion. It is not considered a first-line therapy in most cases of erectile dysfunction, but it is an appropriate therapy for well-counseled individuals who have not responded to other therapies or have found them to be unsatisfactory.
Who is a candidate for a penile prosthesis?
Penile prostheses are usually placed in men with organic erectile dysfunction. In men with psychogenic erectile dysfunction, extensive counseling should be used and other treatment options should be exhausted before a penile prosthesis is considered. For all other patients, there should also be extensive patient and partner counseling before placement of a prosthesis; the expectations, indications, and risks need to be discussed clearly, as well as other currently available and future options. A penile prosthesis is not the usual first-line therapy for erectile dysfunction. When I discuss penile prostheses with patients, I equate the procedure with crossing over a rickety bridge that collapses once you have the prosthesis placed. You cannot go backwards once the prosthesis is placed; if it is removed because of infection, malfunction, or dissatisfaction, other options of treatment are unlikely to work. Although there have been reports of the vacuum device and injection therapy working in some individuals after removal of a prosthesis, these instances are not common. Thus, it is best to try all available therapies and determine whether they are successful and satisfactory before the placement of a prosthesis.
Indications for a penile prosthesis include:
- Patient's unwillingness to consider, failure to respond to, or inability to continue with other forms of treatment, such as oral therapy, injection therapy, MUSE, and the vacuum device
- Postinjection therapy penile fibrosis
- Peyronie's disease and erectile dysfunction
- Postpriapism erectile dysfunction
- Sex change operations in women who undergo surgical creation of a penis
- Penile amputations in men, who then undergo surgical creation of a penis
- Psychogenic erectile dysfunction, after extensive counseling and evaluation
- Neurogenic bladders requiring condom catheters for urinary drainage
How does one use the penile prosthesis and how is it placed?
As Mr. Stanley indicated, placement of a penile prosthesis is a surgical procedure that can be performed under general anesthesia (unconscious state in which there is no pain sensation) or spinal anesthesia (anesthesia produced by injection of a local anesthetic into the subarachnoid space around the spinal cord.). You stay in the hospital overnight (i.e., inpatient) and are usually able to go home the following morning.
To minimize the risk of infection, your scrotal area is shaved, and you are scrubbed with an antibacterial soap for 10 to 15 minutes. In addition, you are given intravenous antibiotics to kill any residual bacteria that may be on your skin. These intravenous antibiotics are continued during your hospital stay, and you are discharged to home with a 10- to 14-day supply of oral antibiotics.
Once you are asleep or your spinal anesthesia is functioning, you are shaved and prepped. A Foley catheter is placed through your penis into your bladder to empty the bladder and to allow for identification of the urethra, the tube you urinate through (which has the catheter in it), to prevent injury to it during the surgery. There are three different approaches to placement of the penile prosthesis, and the location of the incision varies with the type of prosthesis that is being placed and your surgeon's preference:
- A subcoronal incision, a circumcision-type incision, is used for placement of semirigid prostheses.
- A penoscrotal incision is used for the multipart prostheses, for reoperations, and in cases of penile fibrosis (scarring). The incision is made in the midline of the upper part of the scrotum. If you look at your scrotum, you will see that there is a line running up the middle of the scrotum; the incision is made in this line so that when it heals, it will be incorporated in the normal scrotal line.
- An infrapubic incision is used by some surgeons for placement of multipart prostheses. This incision is made below the pubic bone near the base of the penis.
Usually, all components of a multipart prosthesis can be placed through a single incision. Sometimes, prior abdominal and groin surgery, such as a hernia repair or a radical prostatectomy, can make placement of the reservoir of the three-piece prosthesis difficult. In this situation, your surgeon may make another incision on your abdomen to enable the reservoir to be placed. Each corpora cavernosa is opened and dilated to accommodate the cylinder. Each corpora is then measured. Your penis is actually a lot longer than you think - it extends back behind your pubic bone - and it is very important that the correct size cylinder be placed. The pump is placed either in the midline of your scrotum between the two testicles or on one side of the scrotum. You should discuss pump placement with your surgeon before surgery to ensure that it is being placed in a location that is easiest for you to maneuver, particularly if you do not have good use of both hands.
It is important that the corpora are fully dilated and that the appropriate-length cylinders are selected. If the cylinders are too short, they will not provide adequate support to the tip of the penis, causing the glans to droop. This drooping of the glans may make it difficult for vaginal penetration. The glans droop can be corrected by a simple surgical procedure and often does not require replacement of the prosthesis. If the cylinders are too long, they may cause discomfort during intercourse.
The reservoir in the three-piece unit is placed in the pelvis near the bladder. The tubing that connects the reservoir, pump, and cylinders runs deep under your skin so that it is not visible; if you feel closely, you may be able to identify the tubing, but the goal is to have it unnoticeable. Before the procedure is completed, your surgeon will test the prosthesis to make sure that all components are working well, that when inflated it gives you a fully rigid erection, and that the tips of the prosthesis are in a good position in the tip of your penis. Before the incision is closed, a small drain is placed to prevent a hematoma (collection of blood) from forming, and the prosthesis is deflated. The surgeon may leave the prosthesis partially inflated and then deflate it the following morning; this can sometimes help prevent bleeding. When you wake up from surgery in the recovery room, you will have a catheter in place that drains your urine; a dressing around your penis, which will be taped up against your abdomen; and a drain in place.
In men with erectile dysfunction and prostate cancer who are undergoing a radical prostatectomy for treatment of their prostate cancer, the prosthesis can be placed at the time of surgery, and there does not appear to be an increased risk of infection.
What are the hospital course and the postoperative course like?
The morning after surgery, the drain and catheter will be removed. You will be instructed regarding taping your penis to your abdomen. If the prosthesis was left partially inflated, it will be deflated and should remain deflated during the first month after surgery. During the first month after the surgery, the prosthesis may sometimes "autoinflate," such that you will note that you have a partial erection without using the pump. If this occurs, you should call your surgeon and arrange to be seen to have the device deflated. During this time of healing, your body "walls off" the prosthesis. It does not consider the prosthesis to be part of your normal body and produces a tissue layer around the prosthesis. It is important that this tissue layer (called a capsule) forms around a full reservoir so that autoinflation will not be a long-term problem.
You are discharged to home after you have voided. You will receive prescriptions for antibiotics and pain medications. You can shower roughly 3 days after your surgery and tub bathe in 1 week. You will be seen periodically during the first month after your surgery to ensure that all is healing well and that there are no signs of infection. You should contact your physician if you are noting increasing pain, swelling, drainage from your incision, or fever during this time.
You will be taught how to use your prosthesis after the healing is complete and you are comfortable. This usually takes 4 to 6 weeks. Don't be surprised to find it difficult to use at first. It is often helpful to bring your partner with you to this visit so that the two of you can work on figuring it out together. There are movies and instructional booklets that your surgeon can provide to assist you. I find that letting men take a sample prosthesis home with them is helpful in getting to know the prosthesis. Don't get discouraged - if you are having troubles working with the prosthesis, call your surgeon. All it takes is more education and more practice.
What is the success rate of the pen ile prosthesis?
In well-counseled individuals, the success/satisfaction rate of the penile prosthesis ranges from 80 to 91%. Partner satisfaction rates have been reported at 70-90%. In fact, in one study, 92% of patients and 90% of partners indicated that they would choose the implant surgery if faced with the option again.
What are the risks and complications of a penile prosthesis?
As with any surgical procedure, there are complications associated with the placement of a penile prosthesis. These may be subdivided into intraoperative (those occurring during surgery) and postoperative (those occurring after surgery).
Intraoperative (During Surgery) Complications
Perforation: During dilation of the corpora cavernosa, the dilating instrument can perforate the urethra. If this occurs, the procedure must be terminated, the catheter must be left in place, and the urethra must be allowed to heal. If one cylinder has already been placed on the other side, it may be left in place and connected to the pump and reservoir before the surgery is completed. If the patient desires, the surgeon can go back in a few months and try to replace the cylinder. Some men find that they are able to achieve adequate rigidity with only one cylinder in place and do not wish to undergo another surgery.
Similarly, during dilation of the corpora, a hole may be made from one corpus cavernosum into the other. One can proceed with surgery in this case, but it is important to make sure that the cylinders are properly placed in each corpus cavernosum. If a hole is made, a cylinder may cross over, meaning that it starts in one corpus cavernosum but passes through the hole and ends in the other corpus cavernosum. If this situation goes unrecognized, it may cause asymmetry and pain with use of the prosthesis.
Existing scarring that complicates placement: In individuals with significant penile fibrosis/scarring, there may be such severe scarring that narrower cylinders will be required. Rarely, it will be difficult to close the corpora over the cylinders, and a patch of synthetic material or tissue removed from another area of your body will be needed to cover the corporal defect.
Residual curvature of the penis: In patients with Peyronie's disease, placement of the prosthesis and maneuvering of the prosthesis when it is erect in the operating room is usually all that is needed to correct the penile curvature. Rarely, there may be residual curvature after placement of the prosthesis. If this does not improve with use of the prosthesis, then another procedure to excise the plaque may be performed.
Excessive bleeding and anesthesia complications: Finally, as with all surgical procedures, there are bleeding and anesthetic risks.
Postoperative (After-Surgery) Complications
Decreased penile length: This is not a complication; rather, it is intrinsic to the surgery. The cylinders are of a fixed length. To obtain penile rigidity, the cylinders increase in width (girth). Very observant patients will note about a 1- to 2-cm decrease in penile length after the procedure.
Infection: One of the most devastating risks of penile prosthesis surgery is the risk of infection. Infection rates range from 2% to 16% in first-time procedures and increase to 8% to 18% in reoperations. Diabetics and spinal cord injury patients are at increased risk for infection. Signs of infection include persistent pain, erosion of a part of the prosthesis, purulent drainage, fever, swelling and redness of the scrotum, and fixation of the tubing to the scrotal skin. In most cases, particularly those that occur early after implantation, the entire prosthesis must be removed emergently, the area must be irrigated with antibiotics, and intravenous antibiotics followed by oral antibiotics must be given. A second prosthesis can be attempted 6 months later, after all of the healing has occurred. With infections that occur later and are caused by less aggressive bacteria, one can try to salvage (rescue or save) the prosthesis. The patient is taken to the operating room, the infected prosthesis is removed, the area is irrigated copiously with several antibiotic solutions, and a new prosthesis is placed. The risk of infection in the new prosthesis in this situation is about 15%.
Erosion/migration: Erosion (destruction of a tissue surface)/migration (spontaneous change of place) of the prosthesis occurs more commonly with the rigid prostheses and in men with indwelling catheters or in those on clean intermittent catheterization. It may also occur in men whose prosthesis is too long and in those who have an unsuspected urethral injury. In the case of urethral erosion, there may be some splaying of the urine stream and the tip of the prosthesis may protrude into the urethra. The tubing may also erode through the skin; this usually occurs as a result of infection. In patients with urethral erosion, the affected cylinder is removed, and the corpora are irrigated with an antibiotic solution and closed. A catheter is placed into the bladder for about 1 week to promote urethral healing. A new cylinder can be placed 6 months later. In cases of tubing erosion, because this is often a sign of a smoldering infection, the best thing to do is remove the prosthesis. The surgeon can attempt the salvage technique described above.
Lastly, the cylinders can migrate proximally toward the base of the penis, a condition that shows up as a new droop in the glans. When this happens, the cylinder is removed, the defect in the corpus cavernosum is corrected, and the cylinder is replaced.
Glans droop: As indicated earlier, if the cylinders to be implanted are too short, they will not provide adequate support to the tip of the penis, causing the glans to droop. This drooping of the glans may make it difficult for vaginal penetration. The glans droop can be corrected by a simple surgical procedure and often does not require replacement of the prosthesis.
Penile ischemia/necrosis: This complication is extremely rare. It occurs if there is injury to the blood supply to the corpora cavernosa or to the glans. Men with severe diabetes, those with extensive vascular disease, and those who require an extensive dissection for placement of the prosthesis are at increased risk. If the postoperative dressing is too tight, it may cause ischemia.
Perineal pain: There is often some discomfort for the first 2 months or so after placement of a penile prosthesis. If the pain persists longer than this, your physician may evaluate whether you have an infection or whether the prosthesis is too large. Sometimes, there may be some initial penile discomfort with inflation of the prosthesis that is related to stretching of the tunica (the thick white membrane wrapped around the corpora cavernosa), but this usually resolves with time as the tunica stretches.
Residual penile curvature: In patients with Peyronie's disease, placement of the prosthesis and maneuvering of the prosthesis when it is erect in the operating room is usually all that is needed to correct the penile curvature that can occur with this condition. Rarely, there may be residual curvature after placement of the prosthesis. If this does not improve with use of the prosthesis, then another procedure to excise the plaque may be performed.
Mechanical problems: The incidence of mechanical problems with prostheses now is only about 5%, which is quite low. Such mechanical problems include leaks, aneurysms, and rupture of the cylinders. Leaks typically occur at connection sites and where the cylinder tubing enters the cylinder. Leaking prostheses will either not work or will not provide adequate rigidity. Connection site leaks may be easily repaired. A leaking cylinder can be replaced, but it is recommended that the entire prosthesis be replaced if the prosthesis has been implanted for a few years.
Aneurysms (i.e., dilations of a part of the cylinder) are very uncommon with the current prostheses and necessitate removal and replacement of the affected cylinder. The cylinders can also rupture, usually as a result of unrecognized damage during the closure of the corpora. This problem is often detected when the device is inflated 4 to 6 weeks after surgery.
Autoinflation: Autoinflation is the phenomenon whereby the device inflates on its own without pumping the pump. This is the result of increased pressure around the reservoir. Autoinflation may occur intermittently during the first month after placement of the prosthesis but should not occur thereafter. It is important during the first month to deflate the prosthesis quickly to prevent persistence of the autoinflation. If an adequate space was not created for the reservoir at the time of surgery, the autoinflation will not resolve, and an additional procedure will be required.