Penile implant surgery

Anatomy or system affected: Genitals, reproductive system

Definition: The surgical placement of a prosthetic device inside the penis to make it rigid enough for penetration

Indications and Procedures

Penile implant surgery is performed when all other nonsurgical means of treating impotence, or erectile dysfunction, have been exhausted or are not suitable for the patient. A thorough workup must be performed to diagnose the cause of the impotence, which can be psychogenic or organic. The term “psychogenic” is used when there are no anatomical, hormonal, or physiological problems with the patient’s erectile mechanism; instead, the problem is in the patient’s mind. Organic causes include poor blood flow to the penis, the inability of the erectile cylinders to trap blood in the penis (venous leak), or a problem with the nerves, which is seen in diabetic patients. Impotence may also result from a hormonal disturbance.

Organic causes for impotence can be determined with certain tests, including an analysis of blood chemistry and hormone levels, as well as a test for the presence of erection during sleep. Finally, the physician may perform an invasive test in which a drug is injected into the penis so that the erectile response can be observed. Usually, less aggressive, nonsurgical treatments, such as medications, are tried first. If they fail, then penile implant surgery is considered.

There are two types of implants: one is semirigid and malleable, and the other is inflatable. Semirigid rods, the earliest type of penile prostheses, are inserted into the corpora cavernosa (erectile tissue) in the penis. The advantages of this type are a simple surgical technique, lack of mechanical failure, and low cost. The disadvantages include poor cosmetic results because of a permanently rigid penis, which is difficult to conceal, and the extrusion of the penile implant. The malleable prosthesis is like a semirigid one, except that it can be bent in the middle so that concealment is not as difficult. Lifting the prosthesis upward makes it rigid. The design of these prostheses is based on a central wire with multiple springs that cause the penis to become erect when the prosthesis is pulled upward, and the springs come into position so that they support one another.

The second group of penile prostheses is inflatable. These multicomponent prostheses contain two cylinders that fit in the corpora cavernosa. The fluid from a reservoir is pumped into the cylinders to achieve an erection. After the prosthesis has been used, the fluid is pumped back into the reservoir, and the penis becomes flaccid. There are two types of inflatable prosthesis: one in which the pump and the fluid reservoir are combined (two-component type) and one in which the pump is separate from the reservoir (three-component type). The advantage of this type of penile prosthesis is that it more closely mimics a natural erection, in which the penis not only elongates but also expands in diameter. In addition, the penis is closer to a normal shape when in a flaccid state. The disadvantages are significantly higher cost, the chance of mechanical failure in the connections and tubing, and the chance of leakage of fluid from the reservoir or the cylinders. The total time of the operation is slightly more for inflatable penile prostheses than for semirigid and malleable prostheses.

The surgical approaches for the placement of a penile prosthesis are the same for semirigid, malleable, and inflatable types. In the infrapubic approach, the patient is placed on his back. An incision is made at the junction where the penis meets the body, just above the penis in the lower part of the abdominal wall. After the skin and fatty tissues are cut, the corpora cavernosa are exposed. While carefully protecting the nerve responsible for sensation in the penis, the surgeon opens and dilates the corpora cavernosa. The lengths of the corpora are measured, appropriate-length artificial cylinders are inserted, and the corpora are closed.

In the case of semirigid and malleable prostheses, the operation ends after the skin is closed. In the case of an inflatable penile prosthesis, however, two extra steps are taken. A place is created for the pump and reservoir. In a two-component inflatable penile prosthesis, a pocket is created for the combined pump and reservoir just underneath the skin of the scrotum in an area that is easily accessible to the patient. In a three-component penile prosthesis, a pocket is created in the scrotum for the pump, and a space is created for the reservoir in the lower part of the abdomen, above the pubic bone, and in front of the bladder. The reservoir is connected to the pump, and in this fashion, the placement of the prosthesis is completed. An appropriate amount of fluid is left in the reservoir based on the length of the cylinders. The penile prosthesis is evaluated for proper function and cosmetic appearance, and the incision is closed.

Uses and Complications

In the immediate postoperative phase, the cylinder of the inflatable penile prosthesis is left totally deflated so that a scar forms around the pump and reservoir that will allow the normal function of the prosthesis in the future. After two weeks, the cylinders are cycled: the patient inflates his penile prosthesis for thirty to sixty minutes every day and then deflates it. In about six weeks, the pain should have subsided significantly so that the patient is ready to use his penile prosthesis for sexual intercourse. Close monitoring ensures that no infection develops, and the patient is asked to report to the doctor immediately if there is any redness or swelling in the area, which are signs of an impending infection. If an infection occurs, it is initially treated aggressively with antibiotics. If antibiotic therapy does not work, the penile prosthesis may have to be removed.

The complications associated with penile implants include infection, mechanical failure (resulting in the loss of pump or reservoir function), and inadvertent inflation of an inflatable penile prosthesis when the patient sits or stands up. In certain cases, the penile prosthesis can also migrate forward or backward. It can even perforate the corpora cavernosa and extrude through the penis, an emergency that needs to be corrected immediately. There is a remote possibility of gangrene of the penis if infection and extrusion take place simultaneously.

Perspective and Prospects

Penile implant surgery is an excellent procedure for patients who have problems with impotence that are not treatable with medication in that the implant allows them to achieve an erection rigid enough for penetration. This surgery is more applicable in younger patients who have become impotent, either because of diabetes mellitus or after surgical treatment of prostate or rectal cancer, which can lead to damage of the nerves responsible for erection. An older age is not a contraindication for penile prosthesis, however, if the patient is in good physical condition and wants a penile prosthesis. In all cases, it is important that surgery be performed only after significant counseling with the patient, who should understand all the benefits and risks.

The technology involved in penile implant surgery has evolved since the 1970s, starting from a simple, rigid prosthesis and leading to an inflatable, multicomponent prosthesis. The incidence of mechanical failure in the multicomponent inflatable prosthesis is constantly decreasing, and some companies that manufacture this type offer a lifetime warranty. An advance in penile implants in the early twenty-first century included models with improved discreteness, more efficient inflation and deflation apparatus, and more realistic style.

Bibliography

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