Dr. Brantly Scott, the inventor of the IPP, first used the MM technique to correct penile curvature after an IPP placement; however, the original PP cylinders did not provide enough rigidity while inflated to withstand the high-pressure forces required for modeling.9,10 It was Wilson and Deck who initially published the MM technique in 1994, wherein 138 PD patients underwent placement of a three-piece IPP with MM.9,11,12
After placement of the cylinders, closure of the corporotomies, placement of the reservoir and connection of all components, the prosthesis is inflated to the maximum distention. The tubing outlets connecting both of the PP cylinders to the pump are clamped with rubber shods to prevent back pressure from damaging the pump mechanisms. The shaft of the penis is forcefully bent contralateral to the penile curve for 90 seconds. The PP device is then inflated to reassess penile curvature after modeling. If penile curvature is still below 30° after one cycle of MM, then one additional MM session is performed for 90 seconds. After a total of two 90-second modeling sessions, the prosthesis is deflated completely. The assistant pulls on the distal guide sutures protruding from the glans as the surgeon reinflates the prosthesis to achieve a rigid erection.13 This deflation and reinflation reseats the cylinders within the corpora and allows the surgeon to evaluate the curvature of the penis.
Ninety percent (n = 124) of these patients claimed they were successful with using their prosthesis during sexual intercourse. MM alone was unsuccessful in 11% (n = 8) of these patients. Distal perforation, corporal cavernosal rupture, and erosion occurred in four patients. 9
In a different single-center study in 2010, Levine et al. noted a 79% success rate for IPP placement with MM. Nineteen percent had a residual curvature greater than 20°. Eighty-four percent reported postoperative satisfaction. The most common complaint was the loss of penile length.12 Mulhall et. al. determined that if the preoperative penile curvature was less than 30°, no additional straightening maneuvers were required. Twelve and a half percent required straightening if the preoperative penile curvature was 31°-45°, 75% required straightening if the preoperative penile curvature was 46°-60°, and 100% required intraoperative adjuvant straightening maneuvers if the preoperative penile curvature was greater than 60°.14
MM, however, is not successful in every case, as demonstrated in a single-center trial conducted by Kadioglu et al. Straightening of the penis was accomplished by IPP implantation alone in 35% (n = 21) of patients. An additional 30% (n = 30) had successful straightening by MM. Thirty-three and one-third percent (n = 20) were unsuccessful in MM alone and underwent successful incision of the plaque and grafting. Patient satisfaction scores were also tracked during this study. For the MM only group, 83% rated their satisfaction level as excellent, 5.5% rated their satisfaction as satisfactory, and 11.1% rated their satisfaction as poor.15
Wilson et al. followed PD patients who received MM during IPP placement for up to 12 years. Of the 104 PD patients who received an IPP implant with MM, there were 24 (23.1%) cases of IPP failure of any type. Of those failures, 5 became infected, 5 failed for iatrogenic causes, and 13 patients underwent mechanical revisions. Remarkably, patient dissatisfaction was extremely low, with only one patient expressing dissatisfaction in a long-term follow-up. Importantly, there was no statistical difference between the modeling and nonmodeling group in infections, failure due to iatrogenic causes, and mechanical revisions. PD patients who received IPP with modeling did not have a difference in long-term device failures requiring revision, as compared to patients who received IPPs without modeling. Additionally, none of the 104 patients needed reoperation for additional straightening. This paper establishes a long-term safety profile for MM, as modeling appears to provide permanent straightening without an increase in revisions.13
Novel techniques have been introduced as adjuvant treatment options for residual penile curvature after an IPP placement. Morey et. al. described a technique that involved plication sutures before an IPP placement.16 Chung et al., who utilized penile plication prior to IPP placement, documented significant improvement to an average of less than 5° of penile curvature. Of 18 patients who completed a 11-month postoperative questionnaire, 15 reported that their penile curvature was adequate for sexual intercourse and reported an improvement in their overall condition. 17 The scratch technique, which was also described, provided a postoperative straight penis with a reduced chance of urethral perforations.18 These newer techniques may be more efficacious for cases of severe penile curvature, as compared to MM.
Table 1
Success rates of manual modeling and satisfaction rates among patients receiving an
Author | Year | Number of Patients | MM Alone Success Rate | Satisfaction Rate |
Wilson9 | 1994 | 138 | 86% | 90% |
Wilson 13 | 2001 | 104 | 77% | 99% |
Kadioglu15 | 2008 | 145 | 83% | 88% |
Levine12 | 2010 | 90 | 79% | 84% |
Garaffa5 | 2011 | 62 | 84% | - |
Chung20 | 2013 | 138 | - | 90% (Coloplast), 86% (AMS)* |
Lucas4 | 2020 | 40 | 87.5% | - |
IPP. *No statistical difference.