Mentor Mark II
The Mentor Mark II was the second-generation version of the Mentor GFS two-piece inflatable penile prosthesis. Its defining change was the removal of the tubing connectors used in the original design, producing a connectorless system intended to be more reliable. Like the GFS, it used paired inflatable cylinders linked to a 25 mL scrotal component that acted as both pump and reservoir, eliminating the separate abdominal reservoir of a three-piece implant. Short-term studies were encouraging, but longer-term data showed the lowest device survival of any multicomponent inflatable prosthesis it was compared against. The Mark II is no longer manufactured. This page is written for men who already have one implanted.
- The connectorless GFS — The Mark II is the second-generation Mentor GFS, defined by the elimination of tubing connectors.
- 25 mL scrotal resipump — Paired cylinders connected to a single 25 mL scrotal component serving as both pump and reservoir.
- Excellent short-term results — A four-year study of 138 patients reported one mechanical problem and 93% patient satisfaction.
- Poor long-term results — In a comparison of five multicomponent inflatables followed for a mean of 66 months, the Mark II had the lowest cumulative proportional survival at 0.750.
- Loss of rigidity was the characteristic failure — Repeated use stretched the tunica albuginea, and the small fluid volume in the resipump could not compensate.
- Discontinued — Withdrawn along with the original GFS, with higher complication rates and poor reliability the presumed reason.
- Superseded — The Ambicor is the only two-piece implant still available; three-piece devices such as the Titan and AMS 700 dominate the market.
About the Mentor Mark II
What Was the Mentor Mark II?
The Mentor Mark II was a two-piece inflatable penile prosthesis for the surgical treatment of severe erectile dysfunction.
It was not a separate product line. It was the revised version of the Mentor GFS, which had been introduced in 1988.
The GFS acronym stands for girth, flaccidity and simplicity.
When the tubing connectors were removed from the design, the resulting device was designated the Mark II.
Both names appear in operative records and in the literature, sometimes as GFS Mark II and sometimes simply as Mentor Mark II or Mentor two-piece.
They refer to the same family of implant.
Why the Connectors Were Removed
Connectors are the joints where tubing meets a component in a hydraulic prosthesis.
Every joint in a fluid-filled system is a potential leak point.
The original GFS faced mechanical reliability issues and infections, and the Mark II was introduced as the subsequent iteration specifically to reduce those problems by removing the need for tubing connectors.
Making a hydraulic implant connectorless was, at the time, a genuine engineering advance.
The same principle drove design changes across the industry, and modern implants are supplied preconnected wherever possible.
The 25 mL Resipump
The Mark II retained the resipump concept from the original GFS.
The paired cylinders of the device were connected to a 25 mL scrotal component that served as both pump and reservoir.
That figure matters more than it first appears.
A three-piece implant typically uses a reservoir holding 65 mL or more, placed in the abdomen or pelvis.
The Mark II had roughly a third of that volume, all of it in the scrotum.
Everything the device could and could not do follows from that number.
What the Small Fluid Volume Meant in Practice
With 25 mL of fluid, the cylinders could expand only to a predetermined girth.
The device came in two width sizes rather than a full range.
When deflated, some fluid necessarily remained in the cylinders, so the penis did not become genuinely soft.
And critically, there was no fluid reserve to draw on if the anatomy changed over time.
Loss of Rigidity Over Time
This is the failure mode most specific to the Mark II, and the one most relevant to a man who has had one for decades.
In a long-term series, loss of rigidity occurred in seven of 50 implants, or 14%, and appeared to be caused by stretching of the tunica albuginea from repeated use.
The limited amount of fluid in the resipump could not compensate for that stretching, which led to progressive loss of rigidity.
In other words, the device did not necessarily break. The penis gradually accommodated to it, and there was no spare fluid to take up the slack.
A man whose Mark II inflates but no longer produces a usable erection is very likely experiencing exactly this.
Short-Term Clinical Results
The early published results were genuinely good.
The Mark II was implanted in 80 men followed for up to 27 months, and in that study there were no mechanical problems at all.
Six of those patients required repositioning of the reservoir pump, and four required post-operative addition of fluid.
A larger four-year study followed 138 patients implanted between October 1988 and December 1991, with follow-up of twelve to fifty months and a mean of 31.7 months.
That study reported a single prosthetic mechanical problem, involving the tubing.
Seven patients required explantation, two of them for post-operative infection.
Thirteen patients required an addition of normal saline through the resipump as an office procedure.
Ninety-three percent of patients and ninety-eight percent of partners reported satisfaction with the prosthesis.
Men who had a previous prosthesis replaced with the Mark II preferred it over malleable and self-contained implants, though no clear preference emerged between different inflatable types.
The conclusion drawn at the time was that the connectorless Mark II had shown few mechanical problems over four years with good patient and partner satisfaction.
Long-Term Clinical Results
The longer-term picture is substantially worse, and this is the honest heart of the device's story.
One series implanted 50 Mentor two-piece prostheses between October 1987 and June 1993 with a mean follow-up of 52.18 months, ranging from six to 72 months.
Seven implants, 14%, were removed for various reasons.
One patient, 2%, had a total fluid leak caused by breakage of the tube at its junction with the cylinder.
One implant, 2%, was replaced because of loss of rigidity.
Two, 4%, were removed for infection and later replaced with semirigid prostheses.
Three patients, 6%, had pump erosion.
The overall complication rate in that long-term series was 28%, described by its authors as much higher than the short-term follow-ups had suggested.
That single sentence explains why the device disappeared. The Mark II looked excellent at two years and poor at five.
Device Survival Compared With Other Implants
The most useful comparative figure comes from a study of 83 patients with two-piece and 283 with three-piece inflatable prostheses, followed for a mean of 66 months.
Thirty-one device-related complications occurred, all of them secondary to fluid leakage.
Cumulative proportional survival was 0.957 for the Mentor Alpha-1, 0.842 for the AMS 700 Ultrex, 0.839 for the AMS 700 CX, 0.783 for the Mentor GFS and 0.750 for the Mentor Mark-II.
The Mentor Alpha-1 was significantly more mechanically reliable than the Mark II.
A trend also favoured the AMS 700 Ultrex over the Mark II, and a broader trend favoured three-piece devices over two-piece devices as a group.
Note the uncomfortable detail in that ranking: the connectorless Mark II scored slightly below the original GFS it was designed to improve on.
How Patients Operated the Device
The patient squeezed the scrotal resipump to move fluid into the cylinders.
The penis became rigid.
A release mechanism returned the fluid to the resipump.
The penis softened, but not completely, because residual fluid remained in the cylinders.
There was no separate abdominal reservoir to locate or squeeze.
Pump Erosion and Scrotal Position
A 25 mL scrotal component is considerably bulkier than the pump of a three-piece implant.
Pump erosion occurred in 6% of patients in the long-term series, and six patients in an earlier series required repositioning of the reservoir pump.
Scrotal component migration and erosion are therefore recognised issues with this specific device.
Any man with a Mark II who notices skin thinning, redness, tethering or discomfort over the scrotal component should be assessed promptly rather than waiting.
Infection
Infection is a risk with every penile prosthesis.
Two of 138 patients in the four-year study developed post-operative infection requiring explantation, and two of 50 in the long-term series were removed for infection and replaced with semirigid devices.
The Mark II predates both antibiotic-impregnated surfaces and hydrophilic coatings, which are standard on current implants and are associated with substantially lower infection rates.
A device infection decades after implantation is uncommon but not impossible and always requires urgent urological assessment.
Mentor Mark II vs the Original GFS
Both are two-piece inflatables using a scrotal resipump.
The original GFS used tubing connectors; the Mark II did not.
The Mark II was intended to be the more reliable of the two.
In short-term studies it performed very well, but in the 66-month comparative analysis its cumulative survival was 0.750 against 0.783 for the GFS.
For a patient, the practical difference is minimal. Both are discontinued, unsupported and decades old.
Mentor Mark II vs Ambicor
The Ambicor is the modern equivalent and the only two-piece implant still on the market.
AMS developed it in 1994 as a self-contained pair of cylinders with a preconnected pump, using a separate scrotal pump to inflate the cylinders without needing a reservoir inside the penile anatomy.
Contemporary two-piece series report considerably better outcomes. In one study with a mean follow-up of about 29 months, two of 22 cases required revision, one for mechanical failure and one for infection, with patient satisfaction of 73% and partner satisfaction of 59%.
A man who liked the simplicity of his Mark II and wants the same concept today is looking at an Ambicor.
Mentor Mark II vs Three-Piece Implants
A three-piece implant places a much larger reservoir in the abdomen or pelvis.
That extra fluid delivers greater girth expansion, genuine flaccidity when deflated, and a reserve that can accommodate gradual tunical stretching.
The comparative survival data are unambiguous: the Mentor Alpha-1 achieved 0.957 cumulative proportional survival against 0.750 for the Mark II.
The Alpha-1 line evolved into the Coloplast Titan, which was introduced in 2002.
Most men having a Mark II replaced today receive a Titan or an AMS 700.
Mentor Mark II vs Malleable Implants
A malleable implant contains no fluid and cannot leak, lose rigidity or erode a pump.
Two patients in the long-term series had their infected Mark II removed and later replaced with semirigid prostheses.
That pathway is still used today. Where corporal scarring after decades with an inflatable device is significant, a malleable implant such as the Coloplast Genesis, Boston Scientific Tactra or Rigicon Rigi10 may be the only device that can be placed safely.
If You Already Have a Mentor Mark II
This is the situation most readers of this page are in.
A Mark II implanted in 1991 is now more than three decades old.
The device is out of production. No cylinders, tubing or resipumps exist anywhere.
No manufacturer warranty is in force and no repair is possible.
If it still inflates, deflates and produces a usable erection without pain, there is no automatic need to remove it.
If it has lost rigidity, will not hold pressure, has become painful, or shows any sign of erosion or infection, it needs urological assessment.
What Assessment Involves
A urologist will take a history of how the device is behaving and when the change began.
Examination assesses cylinder position, corporal condition and the scrotal component, including any skin thinning over it.
Imaging is sometimes used to look for fluid loss or component displacement.
Bring any operative records you have. Knowing whether the device is a GFS or a Mark II is helpful, though it rarely changes the plan.
Revision and Replacement Surgery
Replacing a decades-old prosthesis is not the same operation as a first implant.
Scar tissue forms around implanted cylinders over time and can restrict corporal space.
Removal of the old device and placement of a new one is usually performed in a single operation where tissue conditions allow.
Corporal dilation, scar excision or downsizing to narrower cylinders may be required.
Where fibrosis is severe, a malleable implant may be the only safe option.
Explantation Without Replacement
Some men choose removal without a new implant.
Erectile function does not return after explantation.
Removing cylinders from scarred corpora typically results in shortening and permanent loss of erection.
Where a device is removed for infection, delayed reimplantation is generally harder than immediate exchange.
This decision deserves an unhurried conversation with an implant surgeon.
Does the Mark II Restore a Natural Erection?
No.
Like all penile prostheses, it produced mechanical rigidity.
It did not restore arterial inflow, veno-occlusion or cavernous nerve function.
It did not affect libido, sensation, orgasm or ejaculation, which depend on nerves and hormones rather than on the erectile mechanism.
Does the Mark II Increase Penile Size?
No.
The cylinders expanded to a fixed girth and were supplied in two width sizes.
Girth expansion was limited by the 25 mL resipump volume and was less than a three-piece device achieves.
No penile prosthesis is a lengthening device.
MRI and the Mentor Mark II
Flag for verification before publishing. No current manufacturer MRI conditions statement could be located for the Mentor Mark II, which is expected for a device discontinued decades ago whose manufacturer no longer exists as a separate company.
Recommended page wording: patients with a Mentor Mark II should inform radiology staff of their implant before any MRI scan, and the radiologist should assess the device individually rather than relying on a manufacturer condition sheet.
Do not state or imply that the device is MR Conditional or MR Safe without a verified source.
Regulatory Status
Flag for verification before publishing. The Mark II was marketed in the United States from the early 1990s, but no active FDA clearance or approval number could be verified and the device is no longer supplied.
Recommended page wording: the Mentor Mark II is not currently approved or supplied in any market, and men seeking a penile implant today will be offered a currently regulated device.
Warranty
There is no warranty.
Mentor Corporation's urology business no longer exists as a separate entity, the device is discontinued, and no manufacturer replacement programme applies.
Any surgery involving an existing Mark II is treated as revision surgery and priced accordingly.
Why This Page Exists
The Mentor Mark II cannot be chosen by anyone today.
It matters for two reasons.
First, men still carry these devices, and the characteristic failure mode of gradual rigidity loss is one that patients often misinterpret as their own problem rather than the implant's.
Second, the gap between the Mark II's excellent two-year data and its poor five-year data is one of the clearest lessons in penile prosthesis history, and it explains why short-term device studies should always be read with caution.
Is this device for you?
- •Men who already have a Mentor Mark II or GFS Mark II implanted and want to understand what they are carrying.
- •Men whose implant has gradually lost rigidity and want to know whether that is the device or themselves.
- •Men told they have "an old Mentor two-piece" and want to identify which generation it is.
- •Men considering revision, replacement or conversion to a current device.
- •Patients comparing two-piece and three-piece implants who want the historical evidence behind that choice.
- •Clinicians and students studying the evolution of inflatable penile prosthesis design.
- •Not available — The device cannot be selected by any patient today.
- •No parts, no warranty, no manufacturer support — Failure means revision surgery, not repair.
- •Lowest survival in comparative analysis — 0.750 at a mean 66-month follow-up.
- •Progressive loss of rigidity — 14% in long-term follow-up, caused by tunical stretching the small fluid volume could not compensate for.
- •Pump erosion — 6% in long-term follow-up.
- •Limited girth expansion — Constrained by the 25 mL resipump.
- •Incomplete flaccidity — Residual cylinder fluid prevents a genuinely soft state.
- •No antimicrobial surface — Predates antibiotic-impregnated and hydrophilic coatings.
- •Revision complexity increases with time — Decades of corporal scarring make exchange harder than a primary implant.
How it compares
Every 2-piece inflatable implant a surgeon in our network may propose, side by side. The Mentor Mark II column is highlighted.
| Attribute | Mentor Mark IIMentor CorporationEconomy | AMS Ambicor™Boston ScientificPremium | Mentor GFS™Mentor CorporationEconomy | Uniflate 1000®Surgitek, Inc.Economy |
|---|---|---|---|---|
| Expansion | Fixed predetermined girth; two cylinder widths suppliedFixed predetermined girth; two cylinder widths supplied | Primarily girth / rigidity; not a dedicated length-expanding cylinder | Fixed predetermined girth; two cylinder widths supplied | Dual-chamber cylinders — inner chamber for rigidity, outer chamber adding girth |
| Rigidity | Hydraulic, on demand; constrained by 25 mL fluid volume and prone to decline over years | Hydraulic inflatable rigidity | Hydraulic, on demand; lower than a three-piece system due to limited fluid volume | Hydraulic, on demand; constrained by scrotal resipump volume |
| Antibiotic coating | None — predates both InhibiZone and hydrophilic coating technology | Do not publish a fixed antimicrobial-coating claim without verifying the current model-specific product documentation | None — predates both InhibiZone and hydrophilic coating technology | None — predates both InhibiZone and hydrophilic coating technology |
| Reservoir | None separate; 25 mL scrotal resipump serves as both pump and reservoir | Integrated within proximal cylinder system; no separate abdominal reservoir | None separate; reservoir combined with pump into a scrotal resipump | None separate; scrotal resipump serves as both pump and reservoir, with a self-sealing penetrable fill port |
| Control | Manual — squeeze the scrotal resipump to inflate, release mechanism to deflate | Scrotal pump; bend-to-deflate mechanism | Manual — squeeze the scrotal resipump to inflate, release mechanism to deflate | Manual — squeeze the scrotal resipump to inflate, release mechanism to deflate |
| Concealed when soft | Partially — residual cylinder fluid prevents true flaccidity | Yes, although generally less completely flaccid than many 3-piece implants | Partially — residual cylinder fluid prevents true flaccidity | Partially — residual cylinder fluid prevents true flaccidity |
| Cylinder material | Silicone inflatable cylinders, connectorless tubing | Silicone elastomer construction | Silicone inflatable cylinders with connecting tubing (Mark II connectorless) | Two-layer construction: outer silicone layer, inner Dacron layer |
| Cylinder options | Two width sizes; length options historical and not documented by any active manufacturer | 12.5 mm, 14 mm and 15.5 mm diameters; 14–22 cm lengths depending on diameter | Two widths; length options historical and not currently documented by any active manufacturer | Supplied preassembled and prefilled with a trimmable tail; size range not documented by any active manufacturer |
| Length expansion | None — girth-expanding design only | No dedicated longitudinal-expansion design | None — girth-expanding design only | None — proximal length adjusted by trimming, not by expansion |
| MRI status | Not verified — no current manufacturer statement available; individual radiological assessment required | MR Conditional at specified 1.5T and 3.0T conditions | Not verified — no current manufacturer statement available; individual radiological assessment required | Not verified — no manufacturer statement exists; individual radiological assessment required, and the Dacron cylinder layer should be declared |
| Reliability | 90–95% at 5 yrs* | 90–95% at 5 yrs* | 90–95% at 5 yrs* | 90–95% at 5 yrs* |
*Type-level five-year mechanical survival from published series; not a model-specific figure. See each model page for detail.
At a glance
- Manufacturer
- Mentor Corporation
- Type
- 2-piece inflatable implant
- Price tier
- Economy
- Warranty
- The Mentor Mark II is a discontinued device with no active manufacturer warranty, replacement programme or spare parts. Mentor Corporation's urology business was acquired by Coloplast in 2006 and the two-piece line was not continued. Men with an existing Mark II who require device removal or exchange are treated under standard revision penile prosthesis surgery pathways, and all costs are quoted as revision surgery.
- Connectorless two-piece design — The defining change from the original GFS.
- 25 mL scrotal resipump — Combined pump and reservoir in a single scrotal component.
- No abdominal or pelvic reservoir — Simplified surgical anatomy compared with three-piece devices.
- Fixed-girth cylinders in two widths — Expansion limited to a predetermined girth.
- Office-adjustable fluid volume — Saline could be added through the resipump as an office procedure.
- No antibiotic or hydrophilic coating — Predates both technologies.
Surgeons who implant it
Surgeons in our network who work with the Mentor Mark II. Availability of a specific model is always confirmed in your proposal.
Common questions
Is the Mentor Mark II the same as the Mentor GFS?
Can I still get a Mentor Mark II?
How much fluid did it hold?
Why did the Mentor Mark II lose rigidity over time?
Was the Mark II reliable?
What were the short-term study results?
What were the long-term study results?
Why was the Mentor Mark II discontinued?
Who makes the Mentor Mark II now?
My implant still inflates but I cannot have sex. What is happening?
Can a Mentor Mark II be repaired?
What would replace a Mentor Mark II today?
How does the Mark II compare with the Ambicor?
Is revision surgery harder than the first implant?
What happens if I have it removed without replacement?
Can I have an MRI with a Mentor Mark II?
Is there any warranty on my Mentor Mark II?
Patient reviews
Been treated? Your honest review of Mentor Mark II helps the next patient.
Be the first to share your experience of this device. We read and verify every review before it is published.
Write the first reviewSources
- Fein — The GFS Mark II Inflatable Penile Prosthesis (J Urol 1992;147:66–9)
- GFS Mark II Inflatable Penile Prosthesis: Four-Year Clinical Study
- George, Erkhan & Dhabuwala — Follow-up with Mentor two-piece inflatable penile prosthesis (PubMed)
- Dubocq et al. — Long-term mechanical reliability of multicomponent inflatable penile prosthesis: comparison of device survival (PubMed)
- Fein — Mentor GFS inflatable prosthesis (PubMed)
- Ambicor Two-Piece Inflatable Penile Prosthesis: Background and Contemporary Outcomes
- Evaluation of Satisfaction and Outcomes of Patients Who Underwent Two-Piece Inflatable Penile Prosthesis Implantation
- Patel et al. — Recent technological development of penile prosthesis: a literature review
- Polchert et al. — Narrative review of penile prosthetic implant technology and surgical results
- Update on penile prosthesis — PMC
- The last survivor of unitary and two-piece inflatables — the Ambicor
- A history of penile implants — PMC
- Coloplast completes acquisition of Mentor Corporation's urology business
- Mentor Corporation — product information