Manual Modeling — the Wilson Technique
Manual modeling (MM) is the first-line adjunctive maneuver for correcting residual penile curvature after inflatable penile prosthesis (IPP) placement in men with Peyronie's disease, used in approximately 74.7% of cases where any straightening adjunct is required.[1] Originally described by Wilson and Delk in 1994,[2] the technique has been refined over three decades and remains the single most commonly performed maneuver in PD-IPP surgery.
The concept is elegant: after the inflated cylinders provide internal hydraulic support, the penis is forcibly bent in the direction opposite the curvature to fracture the fibrotic plaque and allow the corpora to straighten along the cylinders.
Historical Background — the Wilson & Delk 1994 Series
The original technique was presented in a 138-patient series that established proof of concept:[2]
| Outcome | Value |
|---|---|
| Straight, rigid erection with modeling alone | 86% (118 pts) |
| Required relaxing plaque incisions (escalation) | 8% (11 pts) |
| Urethral perforation | 3% (4 pts) |
| Prosthesis infection | 3% (4 pts) |
| Mean follow-up | 32 months (9–84) |
| Prosthesis in active use at follow-up | 90% |
| Reported penile shortening | None |
| Reported glanular sensation impairment | None |
The 3% urethral perforation rate in the original series drove a subsequent generation of technique modifications focused specifically on urethral protection — most importantly, sustained pressure on the glans during modeling.
Step-by-Step Technique (Modern Standard)
Step 1 — Complete IPP insertion
Corporotomy, dilation, and bilateral cylinder placement per standard IPP protocol. Reservoir and pump placement completed. Corporotomies closed before modeling to prevent cylinder prolapse during the maneuver.
Step 2 — Maximal device inflation
Inflate the prosthesis to maximum rigidity. This is the central safety and efficacy principle: the inflated cylinders distribute force across the corporal surface, protecting the corpora from collapse and allowing the modeling force to concentrate on the fibrotic plaque rather than the underlying cavernous tissue.
Step 3 — Assess residual curvature
Use a goniometer with the device fully inflated to document the degree and direction of residual curvature. Threshold for intervention: generally >20–30° residual.[3][4]
Step 4 — Apply manual force
- Grasp the penis firmly with both hands — one proximally, one distally
- Bend the erect penis forcibly in the direction opposite to the point of maximal curvature
- The goal is to fracture or disrupt the fibrotic plaque while the inflated cylinders prevent corporal collapse
- Force should be sustained, not sudden — smooth, maximal bend rather than a jerk
Step 5 — Glanular pressure (critical safety maneuver)
Maintain firm pressure on the glans throughout modeling. This is the single most important safety step:[4][2]
- Prevents the urethra from being compressed against the pubic symphysis during forceful bending
- Reduces the risk of urethral perforation — the defining complication of modeling
- The surgeon's non-dominant hand typically supports the glans; the dominant hand performs the modeling bend
Step 6 — Timed intervals
- Hold the bending force for 90-second intervals[4]
- Release, reassess with goniometer, and repeat as needed
- Typical case requires 3–4 cycles to achieve target straightening (<15° residual)
Step 7 — Final assessment
- Goniometer measurement in all planes
- Document final curvature
- If <15° residual → closure
- If 15–30° residual → consider postoperative home modeling (see below)
- If >30° residual → escalate to concurrent plication or grafting (PICS technique)
The Lucas "Optimal Modeling" Series
Lucas and colleagues' 2020 Urology update formalized the modern protocol and reported improved outcomes:[4]
- Mean pre-modeling curvature: 47.8° (range 30–90°)
- Mean post-modeling curvature: 10.6° (range 0–30°, P<0.001)
- Mean curvature correction: 37°
- Additional operative time: ~7 minutes
- No urethral perforation in the series
- No cases of glans hypoesthesia
The Lucas protocol emphasized:
- 90-second intervals (vs. older "until straight" approaches)
- Sustained glanular pressure throughout each cycle
- Goniometric documentation of pre- and post-modeling curvature
- Systematic escalation if 3–4 cycles fail to achieve <15° residual
Extended Corporal Dilation (ECD)
Katlowitz and colleagues (Mulhall group) published 2026 J Sex Med data showing that extended corporal dilation with Hegar dilators ≥14 mm before cylinder placement reduces the need for adjunctive modeling maneuvers in PD patients:[5]
| Parameter | Standard dilation | Extended dilation |
|---|---|---|
| Technique | Dilamezinsert only | Dilamezinsert + serial Hegar ≥14 mm |
| Post-implant residual curvature | Higher | Significantly lower (P=.02) |
| Need for intraoperative adjunct | Higher | Significantly lower (P<.05) |
Mechanism: ECD mechanically disrupts septal and tunical fibrosis during dilation, creating more room for the cylinders to straighten the corpus natively. Adopt ECD as part of the PD-IPP protocol to reduce modeling requirements.
Home Modeling — Postoperative Continuation
When intraoperative modeling leaves 15–30° residual curvature, postoperative home modeling can complete the correction. The Moncada group's protocol has become the reference.[6]
Moncada home-modeling protocol
| Parameter | Detail |
|---|---|
| Start | 4 weeks after IPP implantation |
| Device state | Prosthesis fully inflated |
| Maneuver | Manual bending opposite the residual curvature |
| Duration | Daily sessions |
| Total course | 6 months |
Outcomes (Moncada, 76 patients with ≤30° residual curvature):[6]
- Mean postoperative residual curvature after intraop MM: 29.7° ± 3.2° (range 5–50°)
- ≤10° residual at 3 months: 85.5%
- ≤10° residual at 6 months: 94.7%
- Satisfied or very satisfied with outcome: 92.1%
The implication: for patients with moderate residual curvature at closure, home modeling obviates the need for additional intraoperative surgical maneuvers in the vast majority of cases.
Why Inflatable Prostheses Are Required
The AUA guideline specifically notes: "modeling to maximize curvature correction is difficult to accomplish with semi-rigid devices."[7] Mechanism:
- Semi-rigid devices lack the hydraulic internal pressure that protects the corpora from collapse during bending
- Force applied to a modeled semi-rigid device concentrates on the device itself, risking damage
- Without full inflation, the plaque-fracture mechanism does not occur reliably
Malleable prostheses are therefore not candidates for manual modeling. Patients with severe PD anticipated to need modeling must receive an inflatable device.
Complications
| Complication | Rate | Prevention |
|---|---|---|
| Urethral perforation | 1–3% | Sustained glanular pressure during modeling |
| Cylinder damage / rupture | Rare | Use fully inflated device; avoid sharp instruments near cylinders |
| Prosthesis infection | 1–3% (not elevated) | Standard IPP infection prevention |
| Persistent curvature >30° | 10–15% | Escalate to plication or grafting |
| Additional shortening | Not typically observed | Modeling stretches rather than shortens |
| Sensory change | Rare | NVB preservation during primary dissection |
Urethral perforation
The classic complication and the one every surgeon must prepare for. Presentation is usually immediate — blood at the urethral meatus, loss of Foley balloon integrity if present, or direct visualization of urethral injury at the end of the case. Management:
- Small perforation, no exposed device: Foley drainage 10–14 days, observation
- Exposed cylinder through urethra: Explantation of affected cylinder, urethral repair, delayed reimplantation at 3–6 months
- Large urethral defect: Complete device explantation, urethral repair, suprapubic diversion, staged reimplantation
Cylinder damage
Modern inflatable cylinders are engineered to withstand modeling forces. The Wilson original report and all subsequent series document no increased risk of mechanical failure from modeling. The inflated state distributes force across the cylinder surface, preventing focal stress.
Indication Criteria and Escalation Triggers
Ideal for modeling alone
- Residual curvature 20–60° after IPP insertion
- Non-complex curvature (no hourglass, no hinge)
- No heavily calcified plaque
- Patient willing to comply with postoperative home modeling if indicated
Escalate to plication
- Residual curvature 30–60° after adequate modeling (3–4 cycles)
- Non-complex deformity
- Patient accepting some additional shortening
Escalate to grafting (PICS)
- Residual curvature >60° after modeling + plication
- Complex deformity (hourglass, hinge)
- Calcified plaque that does not yield to modeling
- Severe pre-op curvature (>75°) — sometimes indicates primary grafting
Summary of Adjunctive Ladder Comparison
| Technique | Median correction | Op time added | Complexity | Key complication |
|---|---|---|---|---|
| Manual modeling alone[1] | 26° | Minimal | Low | Urethral perforation 1–3% |
| Optimal modeling (Lucas)[4] | 37° (47.8°→10.6°) | +7 min | Low | None reported |
| Home modeling (postop)[6] | 20° (29.7°→10° at 6 mo) | N/A (postop) | Low | None reported |
| Concurrent plication | 40° | Moderate | Moderate | Palpable sutures, shortening |
| PICS / grafting | 55° | +50–120 min | High | Sensory loss, hematoma |
Technical Pearls
- Always use an inflatable prosthesis when modeling may be needed. This decision is made preoperatively.
- Inflate the device maximally before modeling — full hydraulic support is essential.
- Maintain glanular pressure throughout every modeling cycle — the single most important safety maneuver.
- Use 90-second intervals with goniometer reassessment between cycles. Avoid "sudden snap" modeling.
- Document pre- and post-modeling curvature objectively with a goniometer. Subjective assessment is unreliable.
- Know when to escalate — if 3–4 modeling cycles fail to achieve target correction, move to plication or grafting. Continuing to model past this point adds risk without additional benefit.
- Counsel patients preoperatively about the likelihood of home modeling. Compliance is critical.
- Consider extended corporal dilation (Hegar ≥14 mm) to reduce the magnitude of modeling required.[5]
See Also
- Peyronie's disease — overview
- Prosthesis with adjunctive straightening
- Scratch technique & endocavernosal disruption
- Penile implants — implant models
References
1. Hammad MAM, Barham DW, Simhan J, et al. A multicenter evaluation of penile curvature correction in men with Peyronie's disease undergoing inflatable penile prosthesis placement. J Sex Med. 2025;22(2):349–355. doi:10.1093/jsxmed/qdae192
2. Wilson SK, Delk JR. A new treatment for Peyronie's disease: modeling the penis over an inflatable penile prosthesis. J Urol. 1994;152(4):1121–1123. doi:10.1016/s0022-5347(17)32519-3
3. Conlon WJ, Herzog BJ, Hellstrom WJG. Residual penile curvature correction by modeling during penile prosthesis implantation in Peyronie's disease patients. Int J Impot Res. 2023;35(7):639–642. doi:10.1038/s41443-023-00694-5
4. Lucas JW, Gross MS, Barlotta RM, et al. Optimal modeling: an updated method for safely and effectively eliminating curvature during penile prosthesis implantation. Urology. 2020;146:133–139. doi:10.1016/j.urology.2020.08.055
5. Katlowitz Y, Taniguchi H, Torremade J, Salter CA, Mulhall JP. Extended corporal dilation decreases the need for intraoperative adjuvant maneuvers for residual curvature after inflatable penile implant placement in men with Peyronie's disease. J Sex Med. 2026;23(5):qdag083. doi:10.1093/jsxmed/qdag083
6. Moncada I, Krishnappa P, Ascencios J, Lopez I, Martinez-Salamanca JI. Home modeling after penile prosthesis implantation in the management of residual curvature in Peyronie's disease. Int J Impot Res. 2021;33(6):616–619. doi:10.1038/s41443-020-0325-6
7. Nehra A, Alterowitz R, Culkin DJ, et al. Peyronie's disease: AUA guideline. J Urol. 2015;194(3):745–753. doi:10.1016/j.juro.2015.05.098