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Malleable (Semirigid) Penile Prosthesis (MPP)

The malleable penile prosthesis is the oldest and simplest form of penile implant — paired silicone rods with an internal metallic wire core. The wire provides sufficient axial rigidity for penetration while allowing the penis to be bent downward for concealment.[1][2][3] Although the three-piece IPP is the gold standard in advanced economies, MPP retains important and expanding clinical roles in salvage surgery, refractory priapism, limited-dexterity patients, gender-affirming phalloplasty, and resource-limited settings.[1][3][4]

History & Evolution​

The concept of an intracorporeal penile support dates back > 500 years.[5]

  • 1936 — Nikolaj Bogaraz: first penile prosthesis (autologous rib cartilage graft) in a reconstructed neophallus after traumatic amputation.[6][7]
  • 1940s–1950s — extracavernosal acrylic stents (Goodwin 1952); intracavernosal polyethylene rods (Loeffler, Sayegh).[2][7]
  • 1966 — Beheri: first large series of intracavernosal polyethylene prostheses.[2]
  • 1973–1975 — Small & Carrion silicone prosthesis — paired silicone rods via perineal approach (31-patient series 1975 established the modern era).[2]
  • 1975–1980s — Finney hinged prosthesis (Flexirod) for concealability; Jonas / Jacobi silver-wire-core silicone for true malleability.[2][6]
  • 1983 — AMS 600 introduced braided stainless-steel wire core within silicone — prototype for all modern MPPs.[2][3]
  • 1990s–2000s — AMS Spectra (articulating segments) and Coloplast Genesis (PTFE-coated silver wire).[2][4][8]
  • 2019 — Rigicon Rigi10: six widths, hydrophilic coating.[9]
  • 2010s–present — transgender-specific devices (Zephyr ZSI 100 FTM) and the TUBE / Shah prosthesis.[4][10]

Currently Available Devices​

DeviceManufacturerCoreWidthsCoatingNotable
Tactra (formerly Spectra)Boston ScientificArticulating PTFE segments + stainless-steel cable3 (9.5, 11, 13 mm)ParyleneBest concealability from articulating segments; trimmable
GenesisColoplastTwisted silver wire + PTFE coating3 (9, 11, 13 mm)SiliconeSmooth bending; trimmable; widely used globally
Rigi10RigiconTwisted stainless-steel wire6 (7, 9, 10, 11, 12, 13 mm)HydrophilicWidest size range; surgeon-dipped antibiotic
ZSI 100Zephyr SurgicalSilver wireMultipleSiliconeStandard cisgender model
ZSI 100 FTMZephyr SurgicalSilver wire + pubic-bone anchor plateMultipleSiliconeDesigned for transgender phalloplasty
TUBE / ShahPromedonNitinol (shape-memory alloy)MultipleSiliconeDeveloping-market availability

References: [4][8][9][10][11]

All modern MPPs share paired, trimmable silicone rods with a metallic wire core. Rods are sized intraoperatively by trimming the proximal end to corporal length.[11][4]

Design Principles​

  • Permanent semirigid state — the penis is always partially rigid; bent upward for intercourse, downward against the body for concealment.[12][11]
  • Axial rigidity from the wire core — sufficient for penetration.
  • Lateral flexibility for concealment — articulating-segment designs (Tactra / Spectra) outperform pure wire-core designs.[4]
  • No moving parts — no hydraulics, pump, reservoir, or tubing → mechanical failure is essentially eliminated.[3]
  • Cannot produce a fully erect penis — no girth or length expansion; less natural-appearing than an IPP.[12]

Indications​

Primary scenarios where MPP simplicity offers advantages over IPP:[1][3][13]

  • Poor manual dexterity — arthritis, Parkinson's, stroke, SCI, advanced age unable to operate a scrotal pump.
  • Infection salvage (MIST — Malleable Implant Salvage Technique) — replacement of an infected IPP with a malleable as either definitive or "corporal space-maintaining" placeholder for later IPP conversion.[3][14]
  • Refractory ischemic priapism — early insertion (< 48–72 h) prevents corporal fibrosis and shortening; later exchangeable for IPP.[3][13]
  • Gender-affirming phalloplasty — simpler implantation in the neophallus; comparable complication rates to IPP.[15][16][10]
  • Resource-limited settings — substantially cheaper; outside the US, MPPs are more commonly implanted than IPPs.[1][9]
  • Hostile pelvis — prior pelvic surgery, radiation, mesh hernia repair where reservoir placement is unsafe.[1][13]
  • Penile length conservation — increasingly used for length preservation in severe corporal fibrosis or prior shortening.[1]

Relative contraindications (favor IPP): patients prioritizing natural appearance and concealability; patients with adequate dexterity and no specific MPP indication.

Surgical Technique​

Technically simpler and faster than IPP:[1][3][4]

Approach: penoscrotal (most common), infrapubic, or subcoronal.

Steps:

  1. Bilateral corporotomies (longitudinal tunica albuginea incisions).
  2. Sequential corporal dilation — proximally to the crura, distally to the glans.
  3. Measurement of corporal length (proximal + distal).
  4. Trim rods to measured length.
  5. Insert paired rods into the corpora.
  6. Close corporotomies and wound.

Advantages over IPP: no reservoir → no bladder / bowel / vascular risk; no pump → no scrotal complications; no tubing → no tubing failures; shorter OR time (~72 vs ~87 min for IPP with PD grafting); possible under local / regional anesthesia in select patients.[17]

Infection prevention: same no-touch and antibiotic-irrigation principles as IPP. Rigi10 / ZSI hydrophilic coatings allow surgeon-applied antibiotic dipping; Tactra has parylene coating; Genesis has silicone coating.[4][9]

Outcomes & Satisfaction​

  • Patient satisfaction 75–96% across series / questionnaires.[18][8]
  • Partner satisfaction 65–85%.[18]
  • AMS Spectra (Akdemir): 96.2% patient, 84.6% partner satisfaction at 3.2 yr mean; IIEF-5 5.86 → 22.5; EDITS 71.1.[18]
  • Genesis vs Spectra: no significant difference (EDITS 77.1% vs 75.6%, p = 0.50).[8]
  • Middle East cross-sectional (100 patients, 36% MPP / 64% hydraulic): no significant difference in EDITS.[19]

vs IPP couples' satisfaction: significantly higher with three-piece IPP than MPP (p < 0.001); 7.7% MPP → IPP conversion due to dissatisfaction vs only 0.2% IPP → MPP.[20]

Penile Length​

Habous prospective (n = 133): implant surgery does not decrease penile length. Both groups gained slightly — MPP +0.22 cm length / +0.7 cm girth; IPP +0.62 cm / +1.7 cm.[21] MPP is increasingly used specifically for length conservation in corporal fibrosis — the solid rod maintains corporal space and prevents further contracture.[1][22]

Device Survival & Mechanical Reliability​

Superior to IPP due to absence of hydraulic components:[3][23]

  • Rigi10: 3-yr implant survival from revision 99.2% (605 patients, 46 surgeons, 15 countries); only 0.99% required revision / explantation.[9]
  • Real-world EHR (n = 29,385): 5-yr revision / removal rates similar between IPP (13.9%) and MPP (13.7%, p = 0.77). But mechanical breakdown significantly lower with MPP (6.7% vs 9.1%, p ≤ 0.0001), and explantation higher with MPP (8.4% vs 6.5%, p < 0.05).[23]
  • Highest revision-by-corporal-perforation rate is with MPP (2.6%); highest revision-by-mechanical-malfunction rate is with IPP (5.5%).[20]

Complications​

Cocci 2025 SR (n = 92,777) data across all prosthesis types:[24]

ComplicationMPPIPPNote
Infection0.33–5%0.46–5%Similar rates
ErosionHigherLowerConstant pressure on tissues; more common distally
Corporal perforation2.6%LowerMost common MPP revision indication
Mechanical failureVery rare5.5–15%+Major MPP advantage
Concealability issuesCommonRareConstant semirigid state hard to hide
Displacement / dislocation (5 yr)1.6%2.3%Lower with MPP

Special Populations​

Infection Salvage (MIST)​

Replacing an infected IPP with a malleable during Mulcahy salvage offers:[3][14][25]

  • Gross multicenter original series (n = 58): 93% infection-free; 31% later converted to IPP at 6.7 mo mean, often achieving longer / wider cylinders than the original infected IPP because the malleable preserved corporal space.[14]
  • 2026 VA national analysis (76 patients, 30 centers): 29.5% reinfection rate, significantly higher in diabetics (45.5% vs 20.5%, p = 0.04). Among those without reinfection: 70% retained the MPP definitively; 28% converted to IPP.[25]
  • Functions as a corporal space maintainer — prevents fibrosis and contracture while infection resolves, easing future IPP placement.

Ischemic Priapism​

MPP insertion within 48–72 h of refractory priapism prevents corporal fibrosis and penile shortening. Can later be exchanged for an IPP with potentially longer / wider cylinders.[3][13]

Gender-Affirming Phalloplasty​

MPPs are widely used in the neophallus due to simpler implantation:[15][16][10][26][27]

  • Fraiman meta-analysis: overall complication 37% MPP vs 38% IPP (NS). Top MPP complications: dislocation 14.9%, infection 11.2%, dysfunction 9.1%, extrusion 7.6%. Explantation 13% MPP vs 19% IPP (NS).[15]
  • Sun 2023 infrapubic technique (n = 40): 40% required revision; no erosions or flap loss.[16]
  • ZSI 100 FTM (Pigot 2020): 32% explantation early on, but better 24-mo complication-free survival (74%) vs conventional MPPs (12%, p < 0.05).[10]
  • Levy 2025 ZSI FTM cohort (hydraulic + malleable): 3-yr explantation-free survival poor at 31–39%, no significant malleable vs hydraulic difference. Secondary implantations: 3.5× complication risk.[26]
  • Levy 2026 Delphi consensus established the first standardized phalloplasty implant protocol.[28]

See Penile Implant After Phalloplasty.

Peyronie's Disease​

MPPs can be combined with plaque incision + grafting for complex PD + ED. Fernández-Pascual series (n = 43, MPP or IPP with multiple corporeal incisions + collagen fleece): mean penile lengthening 2.5 cm; 89.7% would recommend; MPP operative time shorter (71.6 vs 86.7 min).[17]

Malleable vs Inflatable — Comprehensive Comparison​

FeatureMalleable (MPP)Three-Piece Inflatable (IPP)
Erection qualitySemirigid; no girth expansionNear-physiologic; girth + length expansion
ConcealabilityDifficult (always semirigid)Excellent (fully deflatable)
Couples' satisfaction75–77% EDITS77–93% EDITS; significantly higher
Mechanical reliabilityExcellent (no hydraulics)5.5–15% failure at 5–11 yr
Operative timeShorter (~72 min)Longer (~87 min)
Surgical complexitySimple (no reservoir / pump)Complex (reservoir + pump + tubing)
CostSignificantly lowerHigher
InfectionSimilar (~0.3–5%)Similar (~0.5–5%)
Corporal perforationHigher (2.6%)Lower
Revision / removal (5 yr)13.7%13.9%
Penile length change+0.22 cm+0.62 cm
Dexterity requirementNoneRequires pump operation
Reservoir complicationsNoneHerniation, erosion, vascular

Summary​

TopicData
First modern MPPSmall-Carrion 1975
Available devicesTactra, Genesis, Rigi10, ZSI 100, ZSI 100 FTM, TUBE/Shah
Patient satisfaction75–96%
Partner satisfaction65–85%
Rigi10 3-yr device survival99.2%
Real-world 5-yr revision / removal13.7%
Mechanical failure rateVery low (6.7% at 5 yr)
MIST success93% infection-free; 31% later converted to IPP
Phalloplasty complication rate37% (comparable to IPP 38%)
Penile length preservation+0.22 cm
Key advantagesSimplicity, cost, durability, no dexterity needed, corporal space preservation
Key disadvantagesDifficult concealment, lower satisfaction vs IPP, no girth expansion

See also: Inflatable Penile Prosthesis, Penile Implants Atlas, Implant Models, Infection, Penile Implant After Phalloplasty.

References​

1. Goodstein T, Jenkins LC. A Narrative Review on Malleable and Inflatable Penile Implants: Choosing the Right Implant for the Right Patient. International Journal of Impotence Research. 2023;35(7):623-628. doi:10.1038/s41443-023-00765-7

2. Martinez DR, Terlecki R, Brant WO. The Evolution and Utility of the Small-Carrion Prosthesis, Its Impact, and Progression to the Modern-Day Malleable Penile Prosthesis. The Journal of Sexual Medicine. 2015;12 Suppl 7:423-430. doi:10.1111/jsm.13014

3. Khera M, Mulcahy J, Wen L, Wilson SK. Is There Still a Place for Malleable Penile Implants in the United States? Wilson's Workshop #18. International Journal of Impotence Research. 2023;35(2):82-89. doi:10.1038/s41443-020-00376-6

4. Chung E, Wang J. State-of-Art Review of Current Malleable Penile Prosthesis Devices in the Commercial Market. Therapeutic Advances in Urology. 2023;15:17562872231179008. doi:10.1177/17562872231179008

5. May E, Hanley M, Mulcahy JJ, Gross MS. Technological Advances in Penile Implants: Past, Present, Future. International Journal of Impotence Research. 2023;35(7):629-633. doi:10.1038/s41443-023-00689-2

6. Giordano A, Smarrazzo F, Cilio S, et al. History of Penile Implants: From Implants Made of Bone to Modern Inflatable Penile Implants. International Journal of Impotence Research. 2023;35(7):601-608. doi:10.1038/s41443-023-00695-4

7. Bretan PN. History of the Prosthetic Treatment of Impotence. Urologic Clinics of North America. 1989;16(1):1-5.

8. Casabé AR, Sarotto N, Gutierrez C, Bechara AJ. Satisfaction Assessment With Malleable Prosthetic Implant of Spectra (AMS) and Genesis (Coloplast) Models. International Journal of Impotence Research. 2016;28(6):228-233. doi:10.1038/ijir.2016.33

9. Wilson SK, Wen L, Carrion R, et al. Safety Outcomes of the First Rigi10™ Malleable Penile Prostheses Implanted Worldwide. International Journal of Impotence Research. 2024;36(8):833-837. doi:10.1038/s41443-023-00761-x

10. Pigot GLS, Sigurjónsson H, Ronkes B, Al-Tamimi M, van der Sluis WB. Surgical Experience and Outcomes of Implantation of the ZSI 100 FtM Malleable Penile Implant in Transgender Men After Phalloplasty. The Journal of Sexual Medicine. 2020;17(1):152-158. doi:10.1016/j.jsxm.2019.09.019

11. Barnard JT, Cakir OO, Ralph D, Yafi FA. Technological Advances in Penile Implant Surgery. The Journal of Sexual Medicine. 2021;18(7):1158-1166. doi:10.1016/j.jsxm.2021.04.011

12. Shamloul R, Ghanem H. Erectile Dysfunction. Lancet. 2013;381(9861):153-165. doi:10.1016/S0140-6736(12)60520-0

13. Verze P, Capece M, Califano G, La Rocca R. Two-Piece Inflatable and Semi-Rigid Penile Implants: An Effective Alternative? International Journal of Impotence Research. 2020;32(1):24-29. doi:10.1038/s41443-019-0213-0

14. Gross MS, Phillips EA, Balen A, et al. The Malleable Implant Salvage Technique: Infection Outcomes After Mulcahy Salvage Procedure and Replacement of Infected Inflatable Penile Prosthesis With Malleable Prosthesis. The Journal of Urology. 2016;195(3):694-697. doi:10.1016/j.juro.2015.08.091

15. Fraiman E, Nandwana D, Loria M, et al. Complication and Explantation Rates of Penile Prostheses in Transmasculine Patients: A Meta-Analysis. Urology. 2024;194:260-268. doi:10.1016/j.urology.2024.08.022

16. Sun HH, Isali I, Mishra K, et al. Surgical Outcomes at a Single Institution of Infrapubic Insertion of Malleable Penile Prosthesis in Transmen. Urology. 2023;173:209-214. doi:10.1016/j.urology.2023.01.001

17. Fernández-Pascual E, Gonzalez-García FJ, Rodríguez-Monsalve M, et al. Surgical Technique for Complex Cases of Peyronie's Disease With Implantation of Penile Prosthesis, Multiple Corporeal Incisions, and Grafting With Collagen Fleece. The Journal of Sexual Medicine. 2019;16(2):323-332. doi:10.1016/j.jsxm.2018.11.014

18. Akdemir F, Okulu E, Kayıgil Ö. Long-Term Outcomes of AMS Spectra® Penile Prosthesis Implantation and Satisfaction Rates. International Journal of Impotence Research. 2017;29(5):184-188. doi:10.1038/ijir.2017.16

19. Altal Y, Al-Huneidy L, Karam A, et al. Patients' Satisfaction Rate After Penile Implant Surgery: A Cross-Sectional Investigation From the Middle East. Scientific Reports. 2025;15(1):34410. doi:10.1038/s41598-025-17391-6

20. Çayan S, Aşcı R, Efesoy O, et al. Comparison of Long-Term Results and Couples' Satisfaction With Penile Implant Types and Brands. The Journal of Sexual Medicine. 2019;16(7):1092-1099. doi:10.1016/j.jsxm.2019.04.013

21. Habous M, Giona S, Tealab A, et al. Penile Length Is Preserved After Implant Surgery. BJU International. 2019;123(5):885-890. doi:10.1111/bju.14604

22. Krishnappa P, Matippa P, Fraile-Poblador A, Lledo-Garcia E, Moncada I. Penile Length Preservation in Penile Prosthesis Placement: Tips & Tricks. International Journal of Impotence Research. 2025. doi:10.1038/s41443-025-01123-5

23. Kohl S, Goebel C, Kuzina A, et al. Inflatable Penile Prostheses Long-Term Revision and Removal Rates Compared to Semi-Rigid Penile Prostheses: A Real-World Analysis From a Global EHR Database. The Journal of Sexual Medicine. 2026;23(3):qdag034. doi:10.1093/jsxmed/qdag034

24. Cocci A, Capogrosso P, Minhas S, et al. Penile Prosthesis Implantation: A Systematic Review of Intraoperative and Postoperative Complications. International Journal of Impotence Research. 2025. doi:10.1038/s41443-025-01108-4

25. Angulo-Llanos L, Sandler MD, Howell NB, Williams A, Masterson TA. Outcomes of Salvage Procedures With Malleable Implants for Penile Prosthesis Infections in the Veterans Affairs National Medical System. The Journal of Sexual Medicine. 2026;23(3):qdag042. doi:10.1093/jsxmed/qdag042

26. Levy M, van der Sluis WB, van Abbema EL, et al. Hydraulic and Malleable Female-to-Male Penile Implants After Phalloplasty in Transgender Individuals: A Retrospective Cohort Analysis. BJU International. 2025. doi:10.1111/bju.16911

27. Levy M, van Abbema EL, Ronkes BL, et al. Out With the Old, in With the New? A Retrospective Comparison of Malleable Erectile Implants in Phalloplasty. BJU International. 2026. doi:10.1111/bju.70166

28. Levy M, Falcone M, Bohr J, et al. Penile Implants After Phalloplasty in Transgender Individuals: A Consensus-Based Surgical Clinical Protocol. The Journal of Sexual Medicine. 2026;23(2):qdaf365. doi:10.1093/jsxmed/qdaf365