The evolution of the inflatable penile prosthetic device and surgical innovations with anatomical considerations

Technological advances in penile implants: past, present, future

Attempts to "cure" erectile dysfunction (ED) are as old as recorded history. The history of penile prosthetic devices dates back over 500 years, when a French military surgeon designed the first known wooden prosthesis to support micturition. There have since been a great many technological advancements in penile prosthetics. Penile implants for the improvement of sexual function date to the twentieth century. Like all human endeavors, penile prosthesis innovations have progressed via trial and error. This review aims to provide an overview of penile prostheses for the treatment of ED since their introduction in 1936. More specifically, we aim to highlight important advances in penile prosthesis development and discuss dead ends that were abandoned. Highlights include two-piece inflatables, three-piece inflatables, and malleable/semirigid, along with modifications and updates to each basic design that improved both insertion and usability. Dead ends include innovative ideas that were lost to history due to a variety of factors. We also look to the future and discuss expected advances, including remotely activated devices and prostheses designed for special populations, including transgender men.

Safety and Efficacy of Inflatable Penile Prostheses for the Treatment of Erectile Dysfunction: Evidence to Date

Erectile dysfunction (ED) is a common problem, and prevalence rates are expected to rise as life expectancy increases worldwide. In more severe cases of ED, penile prosthesis implantation has been an excellent option for patients. Over the past few decades, significant design improvements have been made to the penile prosthesis and modifications to surgical technique to improve clinical outcomes. The purpose of this review is to summarize the safety and efficacy of FDA-approved penile implants in the US market. Design modifications have greatly improved the safety and reliability of the implant. Development of improved surgical techniques has decreased intraoperative injuries and reservoir-related complications. With its high overall satisfaction rates and low risk of complications, the inflatable penile prosthesis remains an excellent option for patients with erectile dysfunction.

Technological Advancements for Treating Erectile Dysfunction and Peyronie's Disease

Over the past decade, there have been several advancements in the technologies available to treatment erectile dysfunction and Peyronie's disease. Vacuum erection devices, penile traction devices, low-intensity extracorporeal shockwave therapy, and penile prosthesis surgery have evolved and are changing the way we treat men's health. Although significant improvements have been made, further work is needed to standardize treatment, create universal algorithms for technological applications, and simply their use.

Technological Advances in Penile Implant Surgery

BACKGROUND

During the last century, surgical management of erectile dysfunction has evolved from an experimental concept to a core treatment modality with widespread use among the men's health community. Over time, innovations in materials, mechanical design elements, device coatings, and surgical technique have provided patients with low-risk, reliable, and reproducible erectile function with high satisfaction rates.

AIM

To provide a foundation for future innovation by improving understanding of historical penile prosthetics and the rationale behind incremental technological improvements for the contemporary Men's Health physician.

METHODS

Literature review was conducted to generate a comprehensive review of historical technological innovations in penile implant surgery. Companies with FDA approved penile prosthetics in use in the United States were contacted for information regarding technological innovations in the past and future devices in development. A separate literature review was performed to identify any significant future device design elements being tested, even in the ex vivo setting, which may have future clinical applications.

OUTCOMES

Technological innovations in penile implant surgery were described.

RESULTS

Current options for the prosthetic surgeon include malleable penile prostheses (MPP), self-contained (2-piece) inflatable penile prostheses, and multicomponent (3-piece) inflatable penile prostheses. Current MPPs consist of a synthetic coated solid core which allow for manipulation of the penis for concealability while maintaining sufficient axial rigidity to achieve penetration when desired. Multi-component (3-Piece) IPPs currently include the Coloplast Titan and Boston Scientific/AMS 700 which consist of a fluid reservoir, intrascrotal pump, and intracavernosal cylinders. The devices have undergone numerous design updates to the cylinders, pump, reservoir, tubing, and external coatings to increase reliability and decrease short- and long-term complications.

CLINICAL IMPLICATIONS

Future innovations in penile prosthetic surgery seek to broaden the indications and applicability to the transgender community and improve both safety and functionality for patient and partner.

STRENGTHS & LIMITATIONS

The review is limited primarily to penile prosthetics approved for current or historical clinical use in the United States and may not be representative of the global prosthetic environment. Additionally, the research and development of future innovations, particularly those provided by device manufacturers, is likely limited by non-disclosure to maintain a competitive advantage.

CONCLUSIONS

Penile prosthetic surgery will undoubtedly remain integral to the treatment of erectile dysfunction, and education regarding the current state of technological innovation will empower the prosthetic surgeon and biomedical engineering community to improve contemporary patient care and drive the development of the next generation of implantable penile prosthetics. Barnard JT, Cakir OO, Ralph D, et al. Technological Advances in Penile Implant Surgery. J Sex Med 2021;18:1158-1166.

Narrative review of penile prosthetic implant technology and surgical results, including transgender patients

Over the past 40 years, the technological and surgical advancements in penile prostheses have led to increased patient satisfaction rates and decreased complication and infection rates. In cis males with erectile dysfunction (ED), these technological improvements tremendously improve quality of life. In female to male transgender patients, prostheses provide the ability to engage in penetrative intercourse and to urinate standing. This review evaluates technological and surgical advancements in penile prosthetics in the context of documented patient satisfaction and complication rates from prosthesis surgeries. Retrospective studies of penile implant usage in female to male gender-affirming surgeries report that infection and complication rates are higher than those seen in cis males. There are newer prostheses developed specifically for female to male reassignment surgeries, but outcome data is limited. Continued research and development are needed to develop more efficacious penile implantation options for gender affirmation surgery.

The history of surgery in disorders of sexual development

Disorders of sexual development (DSD) have been documented throughout human history with fascination. Healers of all cultures have struggled to explain, and later correct with surgery, the physical manifestations of DSD. DSD was portrayed in the mythology, legends, and art of the ancient Greeks, Romans, Sumerians, Babylonians, and Egyptians. Techniques of feminizing genitoplasties date to the time of Celsus in the time of Christ. Acceptable operative therapy for feminine phenotypes of DSD came in the 19th and 20th centuries. Masculinizing procedures, inherently more complex than feminizing genitoplasties, initially were variations of procedures for severe forms of hypospadias. Today most total penile reconstruction procedures use reconstructive and microvascular techniques invented in 20th century.

Infected penile prosthesis: literature review highlighting the status quo of prevention and management

INTRODUCTION

Erectile dysfunction affects over 50% of men 70 years and above, and penile prosthesis (PP) is its third-line treatment. Complications of PPs include infection, however, no formal guidelines exist for its management.

METHODS

We performed a literature search and reviewed 53 recent published literatures of experiences with management of PP infections, prevention, and treatment.

RESULTS

Acute infection can present early with pain and discharge and detection of early signs is of utmost importance. MRI studies are more sensitive than CT studies to diagnose and plan surgical intervention. Introduction of antibiotic impregnated devices attributed to the reduction of infection rates with superiority proven for certain types; the no-touch technique had further reduced this rate. The Mulcahy salvage remains the most widely used surgical approach for treatment despite modifications and novel techniques described; conservative management of PP infections is recently reported with promising results.

CONCLUSIONS

Despite absence of strict guidelines for the management of infected PPs, we reviewed and discussed numerous panel opinions and suggestions throughout literature. More research into the pathology, prevention, conservative management and advances in surgical treatment of this condition are called for to produce guidelines that unite the efforts to tackle these infections.

Initial experience of a single center with the use of ZSI 475 penile prosthesis

Objective

To evaluate surgical outcomes after implantation of the Zephyr ZSI 475 inflatable penile prosthesis (IPP) and patients' quality of life.

Methods

From December 2014 to September 2018, 15 patients underwent prosthesis implantation with ZSI 475. A retrospective review of clinical data was performed. Patients' quality of life after implantation was investigated with Quality of Life and Sexuality with Penile Prosthesis (QoLSPP) questionnaire.

Results

The median age of patients was 57 years and the average follow-up time was 22 months. Twelve patients received a standard implantation due to severe erectile dysfunction (ED); three patients also presented penile curvature and additional corporoplasty with grafting was necessary. Three procedures had to be interrupted due to defects of the insertion tools. In one case a manufacturing defect resulted in a pump leak. In one case, a severe postoperative complication occurred, which requested explanation of the device. During the follow-up, four patients experienced mechanical failure of the prosthesis. Results of QoLSPP questionnaire at 12 months were skewed toward the positive end of the scale in all domains.

Conclusion

In our initial experience, ZSI 475 suffered a high rate of mechanical failures; on the other hand, the company showed great commitment in order to improve the quality and reliability of the device. The lower cost of ZSI 475 may add to the chances of the product to become a cost-effective alternative to treat those patient who need a IPP.

Two-piece inflatable and semi-rigid penile implants: an effective alternative?

Penile prostheses (PPs) are an excellent treatment to be considered for patients suffering from erectile dysfunction (ED), refractory to oral medications, or unwilling to consider intracavernosal injections or other therapeutic strategies. Nowadays the market is dominated by three-piece inflatable penile prosthesis (IPP), which are considered the best option available. However, in some specific cases three-piece IPP may be superseded by semi-rigid penile prosthesis (SRPP) and two-piece IPP. Despite the advantages of these implants, the literature is quite scarce, not robust and rarely takes into consideration the partner's satisfaction. This clearly affects the strength of our conviction. Most of the studies confirm that SRPPs and two-piece IPPs can be considered a valid alternative in patients with hand dexterity issues, refractory ischaemic priapism, neophallus and in cases of complex anatomies. In addition, the ease of placement and the high confidence level of surgeons make them a powerful tool in the armamentarium of urologists.

Penile Prosthesis Complications: Planning, Prevention, and Decision Making

INTRODUCTION

Inflatable penile prosthesis (IPP) is an established treatment option for men with erectile dysfunction (ED) refractory to medical therapy. Standardization of surgical technique and improvements in device construction have reduced all-cause complication rates to less than 5% in recent reports. Nonetheless, complications do exist, and can strongly impact morbidity and the quality of life of patients. Prosthetic urologists must be aware of the constellation of complications that can arise during or after IPP placement.

AIM

To provide a comprehensive review of penile prosthesis complications and discuss preventative strategies, as well as proper preoperative, intraoperative, and postoperative decision making.

METHODS

A review of the available literature from 1973 to 2018 was performed using PubMed with regard to IPP complications.

MAIN OUTCOME MEASURES

We reviewed publications that outlined preoperative planning strategies and the following IPP complications: hematoma, floppy glans, corporal fibrosis, corporal perforation and crossover, urethral injury, infection, impending erosion, and glandular ischemia.

RESULTS

Careful patient and device selection, setting realistic expectations of postsurgical outcomes, and adherence to a perioperative checklist is essential in the preoperative period. Intraoperatively, anticipate corporal fibrosis situations and always dilate laterally during corporal passage to reduce the risk of crossover and urethral injury. Limit perioperative antiplatelet therapy, apply compressive dressing, use a closed suction drain if indicated, and leave the device partially inflated postoperatively to reduce risk of hematoma. After surgery, monitor patients for potential complications that may warrant device explantation or salvage: IPP infection, glans ischemia, and impending erosion.

CONCLUSIONS

By using evidence and expert opinion-based decision-making strategies in the preoperative, intraoperative, and postoperative period of IPP placement, surgeons can reduce the risk of complications and dissatisfaction, even in ED patients with multiple comorbid conditions. Scherzer ND, Dick B, Gabrielson AT, et al. Penile Prosthesis Complications: Planning, Prevention, and Decision Making. Sex Med Rev 2019;7:349-359.

Penile Wobble Effect: Proximal Corporal Deformities as a Cause of Penile Prosthesis Failure

Introduction

Penile structural defects can contribute toward penile prosthesis (PP) surgical complications and suboptimal outcomes. Despite modern improvements in techniques of inflatable PP (IPP) surgeries, suboptimal outcomes arise secondary to unrecognized proximal corporal abnormalities.

Aim

To describe a new observation of IPP failure (wobbly penis) secondary to proximal corporal deformities.

Methods

We performed a retrospective analysis of the Johns Hopkins institutional database of patients who had IPP surgery from May 2006 to March 2017. All cases requiring surgical revisions secondary to proximal corporal deformities were identified. Exclusion criteria included patients who had incidentally discovered proximal corporal deformities intraoperatively or were documented preoperatively to have had a corporal defect.

Main Outcome Measures

Successful reimplantation of a functionally intact PP device.

Results

On clinical grounds, we identified 5 patients with properly cycling but unstable prosthetic devices that were associated with proximal corporal dilatation (proximally from the penoscrotal junction). All patients underwent reduction corporoplasty with prosthesis replacements consisting of controlled expansion IPPs. 3 patients had undergone previous device replacements because of intact cycling but unstable and unusable IPP devices, whereas 2 had a single previous device insertion. Mean age at revision was 67 years. Median IPP duration was 17 years. Median number of previous IPP surgeries was 3. All patients reported IPP stability and satisfaction after revision (median follow-up = 6 months).

Conclusions

Proximal corporal deformities could account for IPP failure. This condition can be under-recognized as observed in the present cases of multiple revisions with a normally cycling device that was not usable. Proper recognition of this problem allows the opportunity for surgical correction with reduction corporoplasty.

Rajih E, Burnett AL. Penile Wobble Effect: Proximal Corporal Deformities as a Cause of Penile Prosthesis Failure. Sex Med 2018;6:267–271.

Penile implants: a look into the future

Inflatable penile prosthesis (IPP) has been around since the 1970’s as a durable and one-time cure for erectile dysfunction (ED). For the past 40 years, many changes have been made to make the device better and currently IPP boasts a high percentage of long-term patient satisfaction. The next paradigm shift in IPP treatment for ED is upon us. Funding for ED related medications and devices has been a hot topic in health policy over the last 10 years. This suggests that the device must improve and patient advocacy and education must increase for IPP to remain as a viable solution for ED. In this paper, we conduct a literature search for innovations in IPP and argue that IPP must constantly improve to compete with oral, injectable, shockwave, and potentially gene therapies.

A history of penile implants

Erectile dysfunction (ED) has long been described by physicians and patients, with treatments for ED proposed starting in the 8^th century BC. In the last 50 years, however, there have been many advances in medical and surgical management of ED, notably the introduction of the inflatable penile prosthesis (IPP) in 1973 and phosphodiesterase type 5 inhibitors (PDE5Is) in 1998. Here we review the evolution of the IPP from 1973 through the current day. The 3-piece device was first described in 1973 by Dr. F. Brantley Scott, who helped found American Medical Systems (AMS) to market and sell the device. In 1983, Mentor (now Coloplast) started marketing a competing device. AMS and Mentor have made multiple modifications to the device over the years, which have increased rigidity, durability and patient satisfaction, and have decreased surgical variability, post-operative infection and spontaneous inflation. Today, the IPP is a safe and effective option for many men who have failed medical therapies, with high satisfaction from both patients and partners.

Longitudinal and Horizontal Load Testing of Inflatable Penile Implant Cylinders of Two Manufacturers: An Ex Vivo Demonstration of Inflated Rigidity

INTRODUCTION

Since the inception of the inflatable penile prosthesis, a new era has been ushered in for the management of erectile dysfunction. Despite multiple innovations to improve function and reliability, there are no current data comparing the biomechanical properties of these devices.

AIM

To compare the resistance of the Coloplast Titan (Minneapolis, MN, USA) with that of the AMS 700 LGX (Minnetonka, MN, USA) penile prosthesis cylinders to longitudinal (penetration) and horizontal (gravity) forces.

METHODS

We compared two cylinder sizes from each company: the Coloplast Titan (18 and 22 cm) and the AMS 700 LGX (18 and 21 cm). To evaluate axial rigidity, which simulates forces during penetration, we performed a longitudinal load compression test to determine the load required to cause the cylinder to kink. To test horizontal rigidity, which simulates the horizontal forces exerted by gravity, we performed a modified cantilever test and measured the degrees of bend for each device. All devices were tested at 10, 15, and 20 PSI to simulate in vivo pressures.

MAIN OUTCOME MEASURES

The main outcome measurement for the longitudinal load test (penetration) was the force required for the inflated cylinder to bend, thereby affecting its rigidity. The main outcome for the horizontal rigidity test (gravity) was the angle of displacement, in which a smaller angle represents a more horizontally rigid device.

RESULTS

Longitudinal column testing (penetration) demonstrated that less force was required for the AMS device to kink compared with the Coloplast implant across all three fill pressures tested. The Coloplast Titan also had a smaller angle of displacement at the modified cantilever test (gravity) compared with the AMS implant across all fill pressures.

CONCLUSION

The Coloplast Titan demonstrated greater resistance to longitudinal (penetration) and horizontal (gravity) forces in this study. The AMS device was very sensitive to fill pressures. In contrast, the Coloplast Titan's ability to resist these forces was less dependent on the device fill pressure.

A Novel Thermal-activated Shape Memory Penile Prosthesis: Comparative Mechanical Testing

OBJECTIVE

To compare a novel nickel-titanium (Ni-Ti) shape memory alloy (SMA) penile prosthesis of our own design with commercially available prostheses using a format similar to mechanical testing done at major penile prosthesis manufacturers. We evaluated the mechanical parameters of commercially available penile prostheses and used this information to guide the development of the Ni-Ti-based physiological penile prosthesis that expands and becomes erect with a small amount of heat applied.

METHODS

A penile prosthesis consisting of an exoskeleton of temperature-tuned Nitinol was designed and prototyped. Mechanical testing was performed in a model of penile buckling, penile lateral deviation, and original penile shape recovery commonly used by penile prosthesis manufacturers for testing.

RESULTS

Our SMA penile prosthesis demonstrated useful mechanical characteristics, including rigidity to buckling when activated similar to an inflatable penile prosthesis (2.62 kgf SMA vs 1.42 kgf inflatable penile prosthesis vs 6.45 kgf for a malleable prosthesis). The Ni-Ti also became more pliable when deactivated within acceptable mechanical ranges of existing devices. It could be repeatedly cycled and generate a restorative force to become erect.

CONCLUSION

An SMA-based penile prosthesis represents a promising new technology in the treatment of erectile dysfunction. We demonstrated that an Ni-Ti-based prosthesis can produce the mechanical forces necessary for producing a simulated erection without the need for a pump or reservoir, comparable with existing prostheses.

Technological Improvements in Three-Piece Inflatable Penile Prosthesis Design over the Past 40 Years

INTRODUCTION

The advent of the penile prosthesis revolutionized the treatment of erectile dysfunction (ED), resulting in near-complete treatment efficacy and high patient satisfaction rates. While several types of penile prosthesis are available, the inflatable penile prosthesis (IPP) is the most commonly used device in the United States.

AIMS

To describe the key modifications to IPPs from the two major manufacturers-American Medical Systems (AMS) and Coloplast-since the invention of the IPP, and to relate these changes to improvements in prosthesis function and patient outcomes based on available literature.

METHODS

Review and evaluation of the literature between 1973 and present describing modifications in IPP design and the influence of these modifications on IPP durability and patient-related factors.

MAIN OUTCOME MEASURES

Data describing the impact of iterative improvements in three-piece IPP design on device function, durability, and patient outcomes.

RESULTS

There were progressive improvements in IPP technology from both major manufacturers not only on the durability of the prosthesis but also on patient outcomes, with fewer device failures and lower infection rates. Notable improvements include incorporation of kink-resistant tubing, changes in the weave or addition of shear- and infection-resistant coatings to cylinder layers, pump and tubing connection modifications, the addition of rear tip extenders, and the incorporation of lockout valves to prevent autoinflation.

CONCLUSIONS

Numerous incremental modifications to the IPP from both major manufacturers since its invention have increased its durability and improved patient outcomes.

Erectile Dysfunction: A Review of Historical Treatments With a Focus on the Development of the Inflatable Penile Prosthesis

Erectile dysfunction has been a concern for men since the beginning of written history. For many men it can lead to severe psychological distress and humiliation. The treatment of erectile dysfunction has advanced significantly over the past 200 years. Men today are presented with many more viable therapy options leading to improved efficacy and more satisfactory sex lives. The objective of this article is to explore historical options for the treatment of erectile dysfunction, with particular emphasis on the development and progression of the inflatable penile prosthesis.

Evolution of penile prosthetic devices

Penile implant usage dates to the 16th century yet penile implants to treat erectile dysfunction did not occur until nearly four centuries later. The modern era of penile implants has progressed rapidly over the past 50 years as physicians' knowledge of effective materials for penile prostheses and surgical techniques has improved. Herein, we describe the history of penile prosthetics and the constant quest to improve the technology. Elements of the design from the first inflatable penile prosthesis by Scott and colleagues and the Small-Carrion malleable penile prosthesis are still found in present iterations of these devices. While there have been significant improvements in penile prosthesis design, the promise of an ideal prosthetic device remains elusive. As other erectile dysfunction therapies emerge, penile prostheses will have to continue to demonstrate a competitive advantage. A particular strength of penile prostheses is their efficacy regardless of etiology, thus allowing treatment of even the most refractory cases.