Rigi10™ Malleable Penile Prosthesis
Also Known As
Prosthetic penile cylinder measurement, penile prosthesis sizing, implant cylinder measurement, corporal length assessment, penile implant sizing
Definition
Cylinder sizing is the critical process of selecting appropriate prosthesis cylinder dimensions during penile implant surgery to ensure optimal fit within the patient’s corporal bodies.1 This procedure involves precise measurement of the corporal length, from the proximal crura to the distal extent near the glans, typically performed intraoperatively after corporal dilation.2 The primary purpose is to achieve satisfactory erectile rigidity for sexual function while minimizing complications such as pain, erosion, or device malfunction.3 Accurate sizing ensures that implanted cylinders are neither too short, which can lead to “floppy glans syndrome” or poor cosmetic appearance, nor too long, which can cause chronic pain, tissue erosion, or S-shaped cylinder deformity.4 The process may utilize specialized measuring tools and techniques, with some prosthetic systems incorporating rear tip extenders to fine-tune the device length for a more precise corporal fit.5
Clinical Context
Cylinder sizing is a crucial intraoperative step during penile prosthesis implantation surgery for patients with erectile dysfunction (ED) who have not responded to or are not candidates for other therapies.1 The procedure begins after creating incisions (typically penoscrotal or infrapubic) to access the corpora cavernosa, which are then dilated to create space for the prosthetic cylinders.2 At this stage, the surgeon meticulously measures the length of the dilated corporal bodies to determine the appropriate cylinder dimensions.3
Patient selection involves thorough evaluation of candidates, typically including men with organic ED from various causes such as diabetes, vascular disease, post-prostatectomy ED, or Peyronie’s disease.4 Research has shown that men with Peyronie’s disease or a history of radical pelvic surgery are at highest risk for shorter measured corporal lengths and may receive shorter implants.5 Preoperative counseling is essential, as patients must understand that the prosthesis aims to provide rigidity for intercourse but typically does not increase penile length beyond the pre-surgical stretched length.6
The sizing process may be influenced by several factors, including corporal fibrosis, previous surgeries, and anatomical variations. Studies have documented an increasing trend in both measured corporal length (MCL) and implanted device size (IDS) over time, with geographic variations noted (longer cylinders in the US compared to outside the US).7 Intra-patient cylinder size discrepancy is rare (2.7% of cases) and should prompt further investigation when encountered.8
Proper cylinder sizing significantly impacts surgical outcomes and patient satisfaction. Appropriately sized prostheses contribute to high patient satisfaction rates, which can exceed 80% with 3-piece inflatable devices.9 Conversely, improper sizing can lead to complications including chronic pain, erosion, device malfunction, or poor cosmetic and functional results.10