What are Penile Implants?
Penile prostheses or penile implants are an effective treatment and an increasingly desirable option for men with Erectile Dysfunction (ED). Men are eligible for implants if they have an established medical cause for ED, fail to respond to non-surgical treatments (such as oral medications, vacuum devices and injection therapy) and are motivated to have surgery to improve erectile function. A penile implant requires a permanent surgical procedure that cannot be reversed. It is important that men talk to their doctor about the advantages and possible risks of having the surgery. This procedure replaces the spongy tissue (corpora cavernosum) inside the penis with rigid, semi-rigid, or inflatable cylinders depending on which type of penile implant is chosen. In all penile implants, the surgically inserted components are concealed within the body. After the procedure, when a man desires an erection he can produce a rigid erection on demand that enables him to have sexual intercourse. Penile implants do not typically lengthen the penis.
What types of implants are available?
There are several forms of penile prosthetics that can generally be categorized into two main types:
Semi-rigid Malleable (Positionable) Rods
Malleable models are used less often and make up about 10% of total devices implanted. Men should avoid this device if they have a spinal cord injury, diabetes or penile irradiation. The malleable penile implant requires surgical insertion of a pair of flexible rods within the erection chambers of the penis. The rods have an outer coating of silicone and inner stainless steel core or interlocking plastic joints. These joints enable the man to place the penis in either the erect or flaccid position. This type of implant produces a constant penile rigidity that merely needs to be lifted up or bent into the erect position to achieve an erection and have intercourse or in the downward position for urination. When the penis is moved up or down, the rods inside bends. Malleable penile implants can be bent in more than one place to create the desired erection. Three malleable devices exist at this time: AMS Malleable 650, Dura-II devices, and the Mentor Acu-Form prosthesis.
Inflatable Devices
Both types of hydraulic inflatable devices have hollow cylinders that are implanted within the erection chambers of the penis. In order to create an erection these inflatable devices use a pump to transfer fluid (saline) into the cylinders via tubing. As fluid is pumped into these cylinders, they expand to enlarge or “erect” the penis. The 2-piece and 3-piece penile implants differ in their location of fluid storage.
2-Piece Inflatable Implants
This is the simpler of the two types of inflatable devices, accounting for approximately 15% of penile implants used worldwide. In the two-component penile prosthesis, one component is the paired cylinders and the second component is the fluid-filled internal pump located inside the scrotum. Compression of the pump results in rigidity by transferring fluid from the back part of the cylinders and pump into the middle portion. To end the erection with a two-component prosthesis, the penis is gently bent down for 5-10 seconds at its mid-shaft, resulting in the fluid being returned to the fluid-filled pump. The AMS 2-piece device (Ambicor) is the only 2-piece model currently available. The advantage of this device is that it is easier to deflate and may be a better device for older men or men with poor manual dexterity. The disadvantage of this device is that in the flaccid state it always contains some fluid and thus the penis will always appear “full” (similar to the penile form after a man has a hot shower).
3-Piece Inflatable Implants
The most commonly used inflatable device is the 3-piece inflatable implant, accounting for approximately 75% of penile implants. This device has paired cylinders and a small scrotal pump, but in addition this device also has a fluid reservoir behind the abdominal wall muscles that is filled with saline solution. Thus, all parts of the device are internal. With these three-component devices, a larger volume of fluid is pumped into the cylinders for an erection by squeezing the concealed pump in the scrotum several times in order to move the fluid from this concealed reservoir into the cylinders that are in the penis. As the cylinders fill, the penis becomes erect and firm. When the erection is no longer desired, a release valve on the pump (in the scrotum) is simply pressed to transfer the fluid back into the reservoir and out from the cylinders, causing the penis to become flaccid. There are five different 3-piece devices available to address most implant situations. The advantage of a 3-piece device is that it is completely flaccid in the deflated state. However, it does require some training to learn how to deflate the device.
One major difference between the hydraulic, inflatable prosthesis and the semi-rigid malleable implant is that the inflatable prosthesis has a more natural feel since it allows for control of rigidity and size. The semi-rigid devices have the advantage of being the simplest of the penile implants and are the cheaper option. One disadvantage to consider is that a constantly rigid penis that resembles neither normal erection nor flaccidity can makes it difficult to conceal under tighter fitting clothing as well as presenting an increased risk for device erosion.
The pros and cons of each treatment option should be carefully discussed with the treating physician to make the best-informed choice and to ensure that the patient has realistic expectations about treatment results.