Rigi10™ Malleable Penile Prosthesis
Also Known As
RTE, Rear Tip Extender
Definition
Rear Tip Extenders (RTEs) are components used in conjunction with inflatable penile prostheses (IPPs), which are medical devices implanted to treat severe erectile dysfunction refractory to non-surgical therapies.¹ RTEs are typically small, often cylindrical, pieces made of silicone or other biocompatible materials that are attached to the proximal (rear) end of the IPP cylinders within the corpora cavernosa of the penis.¹ Their primary purpose is to ensure appropriate sizing and fit of the IPP, particularly when the measured corporal length is between standard cylinder sizes or when a longer non-inflatable segment is desired at the base of the penis.¹
Historically, RTEs were introduced in 1981 to improve the mechanical survival of IPPs by reducing input-tube wear on the cylinders.¹ While the introduction of kink-resistant tubing likely played a more significant role in preventing device leakage, RTEs continued to be used for optimizing cylinder length and fit.¹ They help to properly position the IPP components, such as ensuring the pump is correctly located in the scrotum, especially in devices with fixed-length tubing, thereby preventing upward migration that could cause discomfort or poor cosmesis.¹
The mechanism of action is straightforward: by adding length to the rear of the IPP cylinders, RTEs allow surgeons to customize the overall length of the implant to match the patient’s specific anatomy. This ensures that the cylinders are neither too short, which could lead to an unstable or inadequately rigid erection, nor too long, which could cause pain or erosion. Some surgeons also use RTEs to create a “hammock” for cylinder placement after a proximal perforation or to anchor prostheses in female-to-male transgender patients.¹ RTEs aim to provide a tailored fit that maximizes functional outcomes and patient satisfaction with the penile prosthesis.¹
Clinical Context
Rear Tip Extenders (RTEs) are utilized during inflatable penile prosthesis (IPP) implantation surgery in specific clinical scenarios to optimize device fit and function.¹ Their use is often indicated when a patient presents with long proximal corporal measurements, where standard cylinder sizes alone may not achieve the ideal length.¹ In such cases, RTEs help ensure the IPP cylinders are appropriately sized to the patient’s anatomy, which is crucial for the proper placement of other device components, particularly the pump in the scrotum.¹ This is especially relevant for IPP models with fixed-length tubing, as incorrect cylinder length without RTEs could lead to upward migration of the pump, potentially causing patient discomfort, difficulty with device operation, and suboptimal cosmetic results.¹
RTEs are also employed in more specialized situations. For instance, they can be used to create a “hammock” to support a cylinder after an intraoperative proximal corporal perforation, a complication where the surgical instrument creates an opening at the base of the corpus cavernosum.¹ Additionally, RTEs have been described for anchoring penile prostheses to bone in female-to-male transgender individuals undergoing phalloplasty with IPP placement.¹
The surgical approach for IPP placement can influence the use of RTEs. Studies have indicated that a penoscrotal approach, compared to an infrapubic approach, may be associated with increased proximal corporal dilation and the use of longer RTEs.¹ This difference is thought to arise because surgeons might use additional RTE length with the penoscrotal technique to ensure the pump is positioned lower and more appropriately in the scrotum, a consideration less critical with infrapubic approaches that inherently have longer tubing from the cylinders to the pump.¹
While RTEs serve important functions in achieving tailored IPP sizing, their use is not without potential downsides. Some evidence suggests an association between the use of any RTEs and an increased rate of revision surgery for the IPP.¹ Complications specifically related to RTEs can include dislodgement or retention of an RTE fragment if the primary device requires revision or removal.¹ Such retained components can potentially lead to chronic pain or become a nidus for infection in the long term.¹ Therefore, the decision to use RTEs is made intraoperatively by the surgeon, weighing the benefits of customized fit against potential risks, and considering factors like patient anatomy, the specific type of IPP device, and the surgical technique employed.¹ The impact of RTEs on the overall rigidity and quality of the erection is also a consideration, with concepts like the “Rigidity Factor” being proposed to quantify the ratio of the inflatable (active) portion of the cylinder to its total length, including any non-inflatable RTEs.¹