by director Chris Steidle, MD
A penile implant or penile prosthesis involves surgery to insert one of various types of rigid or semi-rigid forms, some with a pump, into the penis to allow erections sufficient for penetration and sexual intercourse. Penile implants require surgery and are not a method to enlarge the penis.
The concept of the penile prosthesis dates back to early times when it was noticed that several species of animals had what was termed an os penis or biaculum. This is a cartilaginous support to keep the penis erect. The first penile prosthesis was actually a rib graft implanted into the corporal body.
The recent history of penile implants dates back to 1950, when Dr. Scardino implanted the first synthetic material into the penis. Penile implants improved dramatically with subsequent work of many investigators, and penile implant surgery has progressed to a very high level.
The indications for penile implant surgery include vascular disease, diabetes, bladder or prostate cancer surgery or for benign prostate disease, Peyronie's disease, neurologic disease, hypogonadism, pelvic fractures and impotence related to many medical diseases including chronic renal disease, alcoholism, multiple sclerosis, genital trauma, Parkinsonism, and drug therapy.
Some of the contraindications for penile implants include poorly controlled diabetes, mostly because the patient is highly susceptible to infection, and extreme bladder outlet obstruction, because a penile prosthesis can cause a relative increase in outflow obstruction and eventually produce urinary retention.
Penile implant types
When choosing a penile prosthesis, it is important to recognize the major categories. These include:
- rigid, semi-rigid and malleable rods, which produce varying degrees of rigidity
- inflatable prostheses which include two types;
a) the multi-component inflatable prosthesis, and
b) the self contained inflatable prosthesis.
The main objective is to leave the patient with a penisthat allows achievement of sexual intercourse with no complications, when it is desired and in a way that satisfies both partners. There is no single penile prosthesis that is best for all patients so it is imperative that the urologist sit down with the patient and carefully review the risks, benefits, and drawbacks to each type.
When discussing the semi rigid prosthesis, the upside of the balance sheet includes an erection sufficient for penetration. This is called axial rigidity in the urologic spectrum and means the amount of torque that can be placed on the penis. Most of the rigid prostheses are associated with a low mechanical failure rate because there are no moving parts and a fairly simplistic implantation is possible. The downside is that they produce an erectionthat may be noticeably unsightly, and because these devices are the most likely to create an obstruction that can interfere with urination. Also, if prostate surgery is needed in the future, it can be very difficult because of the implant. However, the rigid prothesis is good for men with poor hand mobility, who are relatively elderly, or who do not want the increased risk of malfunction that can result from moving parts.
The one-piece inflatable penile prosthesis offers a compromise between the multi-component inflatable and the semi-rigid device. The downside to this device is that it can sometimes be difficult to manipulate. It doesn't become as erect as the rigid one and it doesn't deflate as much as the multi-component inflatable. Additionally, this device is limited to the "average size penis," and if the patient has an extremely long penis is usually is not adequate.
The multi-component inflatable prosthesis is what we call the "Cadillac" device. It gives the best appearance when erect and is the softest when deflated. It is probably the most popular and there are several major manufacturers including American Medical Systems and Mentor.
Several penile prosthesesare no longer in vogue and do not have a place in modern implant surgery. For example, the small carrying prosthesis introduced in 1973, available in numerous sizes and lengths, was a reasonable device, but failed to produce the axial rigidity necessary for intercourse and was supplanted by better models.
The Jones Prosthesis was a malleable rod consisting of an outer silicone shell and silver wires in a twisted configuration that allowed some degree of torqueing and an accompanying loss of some axial rigidity. This was supplanted with a trimmable version to ensure adequate sizing.
American Medical Systems introduced the malleable prosthesis, which provides a very adequate erection, but one that can be very unsightly. The fact that the normal erection is a hydraulic event was the rationale behind the inflatable device. It has three pieces including a reservoir to store the fluid, cylinders, and a pump which is placed in the scrotum. The pump transfers fluid from the reservoir into the cylinders, thus creating an erection. When one desires to end the erection, the process is reversed with a releaser deflate valve.
Another American Medical Systems product is the controlled expansion inflatable penile prosthesis which provides increased rigidity. It has reinforced non-kinking tubing, revised pump, and a rear-tip system to allow adequate sizing. Mentor also makes an inflatable prostheses as either a two-piece or three-piece inflatable device.
The type of surgery for the implant is generally based on the surgeon's experience and the type of device chosen, but can include:
a perineal approach which is under the scrotum;
a penoscrotal approach which is at the base of the penis on top of the scrotum
the protheses may be placed in the penile shaft, or
an infrapubic incision, which is an incision above the penis.
There are advantages and disadvantages to each device, but the most important parts of implanting a penile prosthesis are the selection of proper length and diameter to fit the corpus cavernosum, the general dilation of the corporal body to avoid perforation proximally, and meticulous attention to detail to avoid infections, which includes preoperative preparation, intraoperative antibiotics, and copious irrigation during the procedure.
Complications of the penile implantinclude infections, which can be disastrous. The cost of treating an infected prosthesis can actually exceed the cost of the original implant. Procedures to avoid infection include use of a surgical bubble system to prevent particles and bacteria from having access to the device.
Another complication includes perforation of the corporal body in the area where the prosthesis is held, which can cause migration of the device. This problem can be managed by creating a Dacron graft to prevent migration. Perforation into the urethra or glans penis can also be disastrous, and any perforation to a potentially infected area, such as the urethra, requires termination of the procedure.
Other problems include tubing kinks, fluid leaks, aneurysm, dilatation of the cylinders, breakage of the wire, silicone spillage, loss of rigidity to the prosthesis, erosion of the reservoir, spontaneous deflation, spontaneous inflation, penile curvature, which is a variant of Peyronie's disease, pump or pumpreservoir migration, and phimosis or paraphimosis, both of which may require circumcision.
Bottom line, any man who is contemplating penile implantsurgery must find an experienced surgeon and know all of the risks before consenting to the procedure.
Steidle, CP. The Impotence Sourcebook. Lowell House. 1998.
Posted January 2002
Last updated January 2009