Michael
Penile prosthesis implantation is performed for erectile dysfunction refractory to conservative treatment. Inflatable and expandable devices are options available to patients. Various implantation methods can be used successfully depending on the patient’s anatomy and preference. This activity reviews best practices for implanting penile prostheses in patients who have failed conservative measures. In addition, the event reviews penile prosthesis placement techniques and highlights the role of interprofessional teams in evaluating and treating patients requiring prostheses.
Penile prostheses (PP) have been an option for men with erectile dysfunction since they were first introduced in 1973. Since then, various devices have been implanted to improve sexual function in men affected by erectile dysfunction (ED). As the global prevalence of ED is expected to increase to over 322 million by 2025, the demand for implantable PP should continue to rise. Associated factors include an aging population and the continued rise in conditions such as obesity, diabetes, and cardiovascular disease that can lead to decreased erectile function.
Anatomy and Physiology
Penile prosthesis implantation requires a detailed knowledge of the anatomy and physiology of the penis. The erectile tissue of the penis is roughly divided into three compartments. These include the corpus cavernosum of the urethra and the paired cylindrical corpus cavernosum of the penis, which form the main erectile bodies. These lower bodies are connected by a midline septum, allowing free communication between the erectile tissues.
The aforementioned compartment is surrounded by several fascial layers associated with erection. The outermost layer, the penile skin, surrounds the superficial (Dartos) fascia. Beneath this layer is the deep fascia (Buck). Buck’s fascia splits, enclosing the cavernous bodies ventrally and dorsally. The spongy body is surrounded by a dense layer of connective tissue, the tunica albuginea. The albuginea fibers are stretched during erection and therefore have rigidity.
The blood supply to erectile tissue is manifold. Superficially, the external pudendal artery supplies the skin of the penis via the femoral artery. The internal pudendal artery maintains the deep blood supply, the three main branches leading to the penis. The bulbar urethral artery supplies the urethra and glans. The dorsal artery branches into circumflex arteries that supply the corpus cavernosum and urethra. Finally, the cavernous arteries branch again to form spiral arteries, which dilate under nerve stimulation to produce an erection. There are multiple anastomotic connections between these vessels.
Venous drainage of the erectile body is less predictable. In most cases, the corpus cavernosum and corpus cavernosum drain into the efferent vein, which drains into the dorsal vein of the penis. The peripheral nerve plexus of the prostate is the endpoint of drainage of erectile tissue. Penile nerve supply and innervation are variable; however, the pathways responsible for erection are well documented. The dorsal nerve originates from the pudendal nerve and supplies sensory and motor nerves to the penis. The pelvic plexus provides autonomic innervation. Sympathetic efferent nerves originate from spinal cord levels T11-L2 and parasympathetic branches from S2-S4. Through parasympathetic stimulation, several neurotransmitters are responsible for smooth muscle relaxation, arterial dilation, venous occlusion, and subsequent erection.
Indications
Currently, penile prosthesis implantation remains the third-line therapy for erectile dysfunction. Urological guidelines recommend PP for ED unresponsive to more conservative treatments such as phosphodiesterase inhibitors and intracavernous injections. Other placement indications include Peyronie’s disease with ED, penile fibrosis, post-erectile cavernous fibrosis, and psychogenic impotence. More recently, prosthetic placement has been useful as an adjunct to gender-affirming surgery.
Contraindications
Penile prosthesis implantation is contraindicated in patients with any of the following conditions:
- Active infection anywhere in the body, especially urinary tract or genital infections.
- Unresolved voiding problems include increased residual urine volume secondary to the neurogenic bladder or bladder outlet obstruction.
- Patients who do not intend to undergo revision surgery.
Equipment
Several options are currently FDA-approved for penile prosthesis implantation. These include extendable devices and inflatable devices. Proper selection of implant type depends on surgeon experience/preference, patient factors, and anatomical considerations. The malleable device consists of two strong intracavernous implants that can be bent to stimulate an erection or down when not used. Advantages include ease of implantation, patient use, and low failure rates. However, erosion rates and patient satisfaction may be slightly lower.
Three-piece inflatable prostheses are the current gold standard because they allow for a rigid erection and relaxation when needed. These devices consist of two cylinders placed in the lower body and filled with saline to create rigidity. Includes a reservoir that can be placed under the rectus muscle or in the space of Retzius and a scrotal pump that controls the device. Alternatively, a two-piece inflatable prosthesis remains a viable option, including a scrotal pump and a gas cylinder with a smaller reservoir. Two-piece devices may be useful in patients with pelvic surgery or radiation history because no dissection is required within the abdomen or pelvis.
Prepare
A thorough history and physical examination should be performed before surgical planning for penile prosthesis implantation.
Specific questionnaires, such as the International Index of Erectile Function (IIEF-5), can be used to determine a patient’s degree of erectile function.
A detailed evaluation of the patient’s previous surgical history should be performed with attention to any major pelvic surgery, including radical prostatectomy, radical cystectomy, colorectal surgery, and kidney transplantation, as incision site and reservoir placement may need to be adjusted. Carefully review past medical history and medications.
Finally, the genitals must be carefully examined. The stretched length and girth of the penis should be assessed. Any curved or palpable plaques should be carefully documented.
As with all implant procedures, infection control remains paramount. Therefore, certain modifiable factors should be addressed before surgery. First, diabetics should be informed of the importance of controlling blood sugar since the hemoglobin A1C is greater than 8. Smoking cessation should be fully discussed before surgery to promote optimal wound healing. Meta-analyses have demonstrated a link between postoperative surgical site infection and smoking.
Technology
Infection control is an important consideration when discussing penile prosthesis implantation. Although antibiotics are not usually given weeks or days before surgery, preoperative parenteral antibiotics must be given. Recent guidelines from the American Urological Association advocate using aminoglycosides plus cephalosporins or vancomycin as first-line prophylaxis. Surgical preparation should be done in conjunction with an alcohol-based skin preparation. Although iodine-based preparations have historically been used in urogenital surgery, recent data suggest that chlorhexidine-based products improve post-implantation skin culture in preparation for surgery. Double gloves should be considered, as “clean” gloves can be used when placing the implant in the correct position after the rest of the dissection. In addition, device manufacturers now offer implants impregnated with rifampicin/minocycline. Alternatively, hydrophilic implants that absorb various antibiotic/antifungal solutions can also be used. A large systematic review confirmed that coated devices had lower infection rates than non-coated devices.
Once the operating room and patient are ready, general anesthesia is administered. Next, a sterile drape prepares the patient from the navel to mid-thigh. A catheter is placed in the sterile field, emptying the bladder. This helps avoid injury to the bladder and helps identify the urethra more clearly. The Iodoform Drape can be placed over the skin and cut open to expose only the penis and scrotum to minimize skin contact. This so-called “no-touch” technology can reduce infection rates.
Depending on the surgeon’s preference and the patient’s anatomy, the three-piece inflatable device can be placed through the subpubic or penoscrotal incision. The subpubic placement allows placement of the reservoir under direct visualization; however, the penoscrotal or high scrotal approach has historically been preferred. Cut the skin and cut the subcutaneous tissue. Using a self-fixating retractor with blunt tissue hooks can aid in dissection. Dissection is performed through the Dartos and then through Buck’s fascia to the albuginea on either side of the urethra. It may be helpful to place fixation sutures in the lower body on either side of the urethra before making the body incision. Doing this helps to cut it open easily and closes it after the cylinder is placed.
A body incision is then performed using Bovie cauterization. Once the body incision has been made, the body may initially be expanded with blunt-tipped scissors. Continuous Hegar dilators can then dilate down the proximal calf and distally to the mid-glans. To avoid body crossing or urethral injury, special care should be taken to ensure that distal dilation occurs in a lateral cranial direction. After the sides have been properly dilated, the surgeon should evaluate the lower extremity crossover by placing dilators in the bilateral corpus and looking for asymmetry. If crossover occurs, the surgeon may abort the remainder of the procedure. Alternatively, the distal perforation can be repaired in 2 layers with absorbable sutures. Proximal perforations can be addressed by passing a nonabsorbable suture through the solid bottom of the cylinder in a “sling suture” fashion.
If a urethral injury occurs, such as irrigation around the catheter coming out of the urethral opening, the procedure should be discontinued and the catheter left in place for a few days. Next, the reservoir was placed in Retzius’ space. This is done by passing the spermatic cord up the outer ring of the groin. The pubic ramus is then palpated, and the space is expanded using blunt-tipped scissors. Additionally, the space can be expanded using a Foley catheter balloon inflated to 60-100cc. The bladder must be fully decompressed before placing the reservoir, as bladder injury is an avoidable complication associated with this step. The empty container can then be guided by a finger into the created channel using a nasal speculum or a clean Yankauer tip. The reservoir should then be test filled to confirm the correct position.
Alternatively, submuscular placement of the reservoir may be an option for patients who have had prior pelvic surgery or complex hernia repairs. After the reservoir is placed, a cylinder measurement should be taken. Measurements should be confirmed verbally by the surgeon, surgical technologist, and, if available, the medical equipment provider. Only after confirmation is the device turned on and ready for implantation. The proper cylinder size is an important part of implant functionality and durability. A suture with a Keith needle is attached to the distal end of the cylinder and loaded through the sac before being placed through the glans. Then repeat the process on the opposite side. Once both cylinders are in place, inflate with 60 ml saline to assess size and positioning. Posterior tip extenders can be used to size the lower extremities more accurately.
The corporal incision is then closed by sewing the corporal sutures together. Additional interrupted sutures can be placed if needed, taking care not to puncture the cylinder. Next, place the scrotal pump by developing a sub-dartos plane. This is performed using a combination of blunt and sharp dissections. A nasal speculum can be used to create a pocket inside the scrotum. The dartos tissue can then be reapplied on the pump. Then connect the plumbing for the pump, reservoir, and cylinder. It must be confirmed that no air enters the system during connection. Then connect the plumbing for the pump, reservoir, and cylinder. It must be confirmed that no air enters the system during connection. Then connect the plumbing for the pump, reservoir, and cylinder. It must be confirmed that no air enters the system during connection.
Once all the components are in place, the skin closes in two layers. Drains may be placed if the patient plans to stay overnight. The drain can be removed at the same time as the Foley catheter removal on the first postoperative day. The penis is then wrapped with sterile gauze and a gentle pressure dressing. The penis should then be placed upon the lower abdomen to limit the downward curvature of the penis postoperatively. Most patients will stay overnight in the hospital after the prosthesis is implanted. This allows for proper guidance on post-operative instructions and the ability to remove the Foley catheter without additional visits to the outpatient clinic. Remove the urinary catheter and confirm that the bladder is adequately emptied. Historically, prophylactic antibiotics have been prescribed at discharge; however, more recent data suggest no significant difference in infectious complications compared with the no-antibiotic group.
Short-term narcotic pain medication may be necessary. Instruct patients to avoid heavy lifting until follow-up 7-14 days later. After removing the sterile dressing, a scrotal support or tight mesh underwear can be used. You can usually shower for 24 hours after the procedure. Finally, instruct the patient to pull the pump caudally several times a day after discharge to prevent displacement.
Complication
Complications are a significant challenge in penile prosthesis implantation, although technological advancements and surgical methods have reduced their occurrence. Among complications, infection is the most concerning and requires prompt attention.
Patients may exhibit acute illness symptoms such as fever, constitutional symptoms, and drainage from the incision site, indicating an immediate need for treatment. Alternatively, indolent infections may remain undetected for months or even years after the implant placement. In such cases, broad-spectrum antibiotics are typically initiated, and removal of all prosthetic components becomes necessary.
It is important to note that literature suggests new implants can be placed immediately after removal, as long as proper irrigation has been performed. Another complication often observed in penile implant surgery is improper cylinder sizing.
If the cylinder is too short, it can lead to supersonic transporter (SST) deformities and “floppy glans syndrome,” causing an unsightly appearance and difficulty with vaginal penetration. Conversely, an excessively large cylinder can increase the risk of chronic pain and erosions.
Significant erosion necessitates the removal of the device. Cranial displacement of the scrotal pump is another challenging complication. It can make pump usage difficult, resulting in unusual penile and scrotal appearance. This complication can be minimized by positioning the pump and tubing beneath the closure of the Dartos fascia layer during the procedure.
Lastly, while device failure is a rare complication following prosthetic implantation, ongoing advancements in implant technology may introduce situations where individual component replacement is considered.
Conclusion
Penile prosthesis implantation is a surgical solution for erectile dysfunction that has not responded to conservative treatments. When selecting an appropriate implant type, it is essential to consider patient factors, anatomical considerations, and surgeon experience/preference. Thorough history taking, physical examination, and patient counseling are crucial before the surgery, ensuring the patient’s expectations are realistic and the risks and benefits are fully understood. Infection control measures and proper surgical techniques should be followed to minimize complications and achieve successful outcomes for patients undergoing penile prosthesis implantation.
