A penile implant is an implanted device intended for the treatment of

erectile dysfunction Erectile dysfunction (ED), also referred to as impotence, is a form of sexual dysfunction in males characterized by the persistent or recurring inability to achieve or maintain a Human penis, penile erection with sufficient rigidity and durat ...

Peyronie's disease Peyronie's disease (PD) is a benign, acquired penile connective tissue disease characterized by the occurrence of fibrotic plaques within the Tunica albuginea (penis), tunica albuginea — the dense elastic covering of the Corpora cavernosa of pe ...

, ischemic priapism, deformity and any traumatic injury of the penis, and for

phalloplasty Phalloplasty (also called penoplasty) is the construction or reconstruction of a penis or the artificial modification of the penis by surgery. The term is also occasionally used to refer to penis enlargement. History Russian surgeon Nikolaj B ...

metoidioplasty Metoidioplasty, metaoidioplasty, or metaidoioplasty (informally called a meto or meta) is a female-to-male gender-affirming surgery. Testosterone replacement therapy gradually enlarges the clitoris to a mean maximum size of (as the clitoris ...

, including in gender-affirming surgery. Men also opt for penile implants for aesthetic purposes. Men's satisfaction and sexual function is influenced by discomfort over genital size, which leads some to seek surgical and non-surgical solutions for penis alteration. Although there are many distinct types of implants, most fall into one of two categories: malleable and inflatable transplants.

History

The first modern prosthetic reconstruction of a penis is attributed to NA Borgus, a German physician who performed the first surgical attempts in 1936 on soldiers with traumatic amputations of the penis. He used rib cartilages as prosthetic material and reconstructed the genitals for both

micturition Urination is the release of urine from the bladder through the urethra in placental mammals, or through the cloaca in other vertebrates. It is the urinary system's form of excretion. It is also known medically as micturition, voiding, ures ...

and intercourse purposes. Willard E. Goodwin and William Wallace Scott were the first to describe the placement of synthetic penile implants using acrylic prosthesis in 1952.

Silicone In Organosilicon chemistry, organosilicon and polymer chemistry, a silicone or polysiloxane is a polymer composed of repeating units of siloxane (, where R = Organyl group, organic group). They are typically colorless oils or elastomer, rubber ...

-based penile implants were developed by Harvey Lash and the first case series were published in 1964. The development of a high-grade silicone that is currently used in penile implants is credited to

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

. The prototypes of the contemporary inflatable and malleable penile implants were presented in 1973 during the annual meeting of the

American Urological Association The American Urological Association (AUA) is a professional association in the United States for urology professionals. It has its headquarters at the William P. Didusch Center for Urologic History in Maryland. AUA works with many international o ...

by two groups of physicians from

Baylor University Baylor University is a Private university, private Baptist research university in Waco, Texas, United States. It was chartered in 1845 by the last Congress of the Republic of Texas. Baylor is the oldest continuously operating university in Te ...

(Gerald Timm, William E. Bradley and F. Brantley Scott) and

University of Miami The University of Miami (UM, UMiami, Miami, U of M, and The U) is a private university, private research university in Coral Gables, Florida, United States. , the university enrolled 19,852 students in two colleges and ten schools across over ...

(Michael P. Small and Hernan M. Carrion). Small and Carrion pioneered the popularization of semi-rigid penile implants with the introduction of Small-Carrion prosthesis (

Mentor Mentorship is the patronage, influence, guidance, or direction given by a mentor. A mentor is someone who teaches or gives help and advice to a less experienced and often younger person. In an organizational setting, a mentor influences the perso ...

, USA) in 1975. Brantley Scott described the initial device as composed of two inflatable cylindrical bodies made up of silicone, a reservoir containing radiopaque fluid and two pumping units. The first generation products were marketed through American Medical Systems (AMS; currently

Boston Scientific Boston Scientific Corporation (BSC), headquartered in Marlborough, Massachusetts and incorporated in Delaware, is an American biotechnology and biomedical engineering firm and multinational manufacturer of medical devices used in interventional ...

), with which Brantley Scott was associated. Many device updates have been released by AMS since the first generation implants. In 1983, Mentor (currently Coloplast) joined the market. In 2017, there were more than ten manufacturers of penile implants in the world, however only a few now remain in the market. The latest additions to the market are Zephyr Surgical Implants and Rigicon Innovative Urological Solutions. Zephyr Surgical Implants, along with penile implants for biological men, introduced the first line of inflatable and malleable penile implants designed for sex reassignment for

trans men A trans man or transgender man is a man who was assigned female at birth. Trans men have a male gender identity, and many trans men undergo Gender transition, medical and social transition to alter their appearance in a way that aligns with th ...

. In recent years, Rigicon Innovative Urological Solutions, a US-based company, has made significant advancements in the field of penile implants. In 2017, they released the 'Rigi10,' a malleable implant that expanded the market's options. Following this, in 2019, they introduced both the 'Infla10' series, which includes the Infla10 AX, Infla10 X, and Infla10 models, and the 'Rigi10 Hydrophilic.' These inflatable and hydrophilic-coated malleable models respectively were important additions to the range of penile implant technologies available. These advancements have contributed to the diversity and progress in the development of penile implants, offering patients more varied and tailored treatment solutions. According to analysis of the 5% Medicare Public Use Files from 2001 to 2010 approximately 3% of patients diagnosed with erectile dysfunction opt for penile implantation. Each year nearly 25,000 inflatable penile prostheses are implanted in the USA. The list shows penile implants available in the market in 2020.

Types

Malleable penile implant

The malleable (also known as non-inflatable or semi-rigid) penile

prosthesis In medicine, a prosthesis (: prostheses; from ), or a prosthetic implant, is an artificial device that replaces a missing body part, which may be lost through physical trauma, disease, or a condition present at birth (Congenital, congenital disord ...

is a pair of rods implanted into the corpora of the penis. The rods are hard, but 'malleable' in the sense that they can be adjusted manually into the erect position. There are two types of malleable implants: one that is made of silicone and does not have a rod inside, also called soft implants, and another with a silver or steel spiral wire core inside coated with silicone. Some of the models have trimmable tails intended for length adjustment. Currently, a variety of malleable penile implants are available worldwide.

Inflatable penile implant

The inflatable penile implant (IPP), more recently developed, is a set of inflatable cylinders and a pump system. Based on the differences in structure, there are two types of inflatable penile implants: two-piece and three-piece IPPs. Both types of inflatable devices are filled with sterile saline solution which is pumped into cylinders when in process. The cylinders are implanted into the cavernous body of the penis. The pump system is attached to the cylinders and placed in the

scrotum In most terrestrial mammals, the scrotum (: scrotums or scrota; possibly from Latin ''scortum'', meaning "hide" or "skin") or scrotal sac is a part of the external male genitalia located at the base of the penis. It consists of a sac of skin ...

. Three-piece implants have a separate large reservoir connected to the pump. The reservoir is commonly placed in the

retropubic space Retropubic space is a potential avascular space located between the pubic symphysis and the urinary bladder. The retropubic space is a preperitoneal space, located behind the transversalis fascia and in front of peritoneum. Other names for the ...

(Retzius' space), however other locations have also been described, such as between the transverse muscle and rectus muscle. Three-piece implants provide more desirable rigidity and girth of the penis resembling natural erection. Additionally, due to the presence of a large reservoir, three-piece implants provide full flaccidity of the penis when deflated, thus bringing more comfort than two-piece inflatable and malleable implants. The saline solution is pumped manually from the reservoir into bilateral chambers of cylinders implanted in the shaft of the penis, which replaces the non- or minimally-functioning erectile tissue. This produces an erection. The glans of the penis, however, remains unaffected. Ninety to ninety-five percent of inflatable prostheses produce erections suitable for

sexual intercourse Sexual intercourse (also coitus or copulation) is a sexual activity typically involving the insertion of the Erection, erect male Human penis, penis inside the female vagina and followed by Pelvic thrust, thrusting motions for sexual pleasure ...

. In the United States, the inflatable prosthesis has largely replaced the malleable one, due to its lower rate of infections, high device survival rate and 80–90% satisfaction rate. The first IPP prototype presented in 1975 by Scott and colleagues was a three-piece prosthesis (two cylinders, two pumps and a fluid reservoir). Since then, the IPP has undergone multiple modifications and improvements for device reliability and durability, including change in the chemical material used in implant manufacturing, using hydrophilic and antibiotic eluting coatings to reduce the rates of infections, introducing one-touch release etc. Surgical techniques used for the implantation of penile prostheses have also improved along with evolution of the device. Inflatable penile implants were one of the first interventions in urology where the "no-touch" surgical technique was introduced. This has significantly reduced the rates of post-operative infections.

Medical use

Erectile dysfunction

In spite of recent rapid and extensive development of non-surgical management options for

, especially novel targeted medications and

gene therapy Gene therapy is Health technology, medical technology that aims to produce a therapeutic effect through the manipulation of gene expression or through altering the biological properties of living cells. The first attempt at modifying human DNA ...

, the penile implants remain the mainstay and the gold standard choice for the treatment of erectile dysfunction refractory to oral medications and injectable therapy. Additionally, penile implants can be a relevant option for those with erectile dysfunction who want to proceed with a permanent solution without medical therapy. Penile implants have been used for the treatment of erectile dysfunction with various etiologies, including vascular, cavernosal, neurogenic, psychological and post-surgical (e.g.

prostatectomy Prostatectomy (from the Ancient Greek language, Greek , "prostate" and , "excision") is the surgical removal of all or part of the prostate gland. This operation is done for benignity, benign conditions that cause urinary retention, as well as ...

). The

recommends informing all men with erectile dysfunction about penile implants as a choice of treatment and discussing the potential outcomes with them.

Penile deformity

Penile implants can help recover the natural shape of the penis in various conditions that have led to penile deformity. These can be traumatic injuries, penile surgeries, disfiguring and fibrosing diseases of the penis, such as

. In Peyronie's disease, the change in penile curvature affects normal sexual intercourse as well as causing

due to disruption of blood flow in the cavernous bodies of the penis. Therefore, implantation of penile prosthesis in Peyronie's disease addresses several mechanisms involved in the pathophysiology of the disease.

Female-to-male sex reassignment

Although different models of penile prostheses have been reported to be implanted after

procedures, with the first case described in 1978 by Pucket and Montie, the first penile implants designed and produced specifically for female-to-male gender reassignment surgery for

were introduced in 2015 by Zephyr Surgical Implants. Both malleable and inflatable models are available. These implants have more realistic shape with an ergonomic glans at the tip of the prosthesis. The inflatable model has an attached pump resembling a testicle. The prosthesis is implanted with a sturdy fixation on

pubic bone In vertebrates, the pubis or pubic bone () forms the lower and anterior part of each side of the hip bone. The pubis is the most forward-facing (ventral and anterior) of the three bones that make up the hip bone. The left and right pubic bones ar ...

. Another, thinner malleable implant is intended for

Outcomes

Satisfaction

The overall satisfaction rate with penile implants reaches over 90%. Both self- and partner-reported satisfaction rates are evaluated to assess the outcomes. It has been shown that implantation of inflatable penile prosthesis brings more patient and partner satisfaction than medication therapy with

PDE5 inhibitor A phosphodiesterase type 5 inhibitor (PDE5 inhibitor) is a vasodilating medication, drug that works by blocking the degradative action of cGMP-specific phosphodiesterase type 5 (PDE5) on cyclic GMP in the smooth muscle cells lining the blood vess ...

s or intracavernosal injections. Satisfaction rates are reported to be higher with inflatable rather than malleable implants, but there are no differences between two-piece and three-piece devices. The most frequent reasons for dissatisfaction are reduced penis length and girth, failed expectations and difficulties with device use. Thus, it is vital to provide patients and their partners with detailed preoperative counselling and instructions.

Curvature correction

33% to 90% of cases of patients with Peyronie's disease that have had an inflatable PI procedure have successfully corrected their penile deformity. The residual curvature after penile implant placement usually requires intraoperative surgical intervention.

Progress in procedure

Dilation of the corpora cavernosa, typically with Hegar sounds, before inserting the device has been a common part of implantation procedures. This dilation destroys erectile tissue. It has been shown that a tissue-sparing technique, i.e. ''without'' dilation, correlates with superior outcomessome remaining natural erectile response can be preserved, and post-operative pain is reduced as well.

Complications

The most common complication associated with penile implant placement appears to be infections with reported rates of 1–3%. Both surgical site and device infections are reported. When the infection involves the penile implant itself, implant removal is required and irrigation of the cavities with

antiseptic An antiseptic ( and ) is an antimicrobial substance or compound that is applied to living tissue to reduce the possibility of sepsis, infection, or putrefaction. Antiseptics are generally distinguished from ''antibiotics'' by the latter's abil ...

solutions. In this scenario, placement of a new implant is needed to avoid further tissue fibrosis and shortening of the penis. The rate of repeat surgeries or device replacements ranges from 6% to 13%. Other reported complications include perforation of the corpus cavernosum and

urethra The urethra (: urethras or urethrae) is the tube that connects the urinary bladder to the urinary meatus, through which Placentalia, placental mammals Urination, urinate and Ejaculation, ejaculate. The external urethral sphincter is a striated ...

(0.1–3%), commonly occurring in patients with previous

fibrosis Fibrosis, also known as fibrotic scarring, is the development of fibrous connective tissue in response to an injury. Fibrosis can be a normal connective tissue deposition or excessive tissue deposition caused by a disease. Repeated injuries, ch ...

, prosthesis erosion or extrusion, change in

glans The glans (, : glandes ; from the Latin word for "acorn") is a vascular structure located at the tip of the penis in male mammals or a homologous genital structure of the clitoris in female mammals. Structure The exterior structure of the g ...

shape,

hematoma A hematoma, also spelled haematoma, or blood suffusion is a localized bleeding outside of blood vessels, due to either disease or trauma including injury or surgery and may involve blood continuing to seep from broken capillaries. A hematoma is ...

, shortening of penis length, and device malfunction. Due to continuous improvement of surgical techniques and modifications of implants, complication rates have dramatically decreased over time. To overcome post-operative penile shortening and to increase the perceived length of the penis and patient satisfaction, ventral and dorsal

procedures in combination with penile implants have been described. Modified glanulopexy has been proposed to prevent supersonic transporter deformity and glandular hypermobility which are possible complications of penile implants. Sliding techniques in which the penis is cut and elongated with penile implants have been performed in cases of severe penile shortening. However, these techniques had higher rates of complications and are currently avoided.

References

External links

* {{Male genital procedures Male genital surgery Men's health Andrology Sexual health Human penis Penile erection Masculinizing surgery Medical devices Medical equipment Implants (medicine) Prosthetics