Before and after an AMS 700 LGX implant, the measurable change is the return of a rigid, on-demand erection rather than growth of native tissue. Most men gain 1 to 3 cm of functional length in the first year compared with their pre-surgery erect measurement, and roughly half recover to within 1 cm of their best historical erection within 24 months. The device does not add tissue; it restores and then modestly recruits corporal volume through controlled cycling. Girth typically rises 0.5 to 1.5 cm by month 12. Claims of 4 cm or more are outliers tied to specific pre-surgical states, not the norm.
What the LGX device actually does before and after
The AMS 700 LGX (Length Girth Expansion) is a three-piece inflatable penile prosthesis with two cylinders that expand in both length and girth as fluid is pumped from an abdominal reservoir. The cylinders are made from Bioflex, a silicone elastomer, and are engineered to lengthen up to 20 to 25 percent beyond their flaccid inflated baseline when fully filled. That expansion is the entire mechanism behind the "before and after" story.
Before surgery, the relevant baseline is not the flaccid length. It is the stretched flaccid length and, more importantly, the best erect length the man achieved in the prior 12 to 24 months. Surgeons measure both, usually with a rigid ruler along the dorsum from pubic bone to tip, pressing through pubic fat. This baseline determines expectations more than any brochure figure.
In plain terms: the implant replaces the hydraulic function of the corpora cavernosa, and its expansion capability does the rest. It cannot create tissue that fibrosis or prior surgery destroyed.
How the length and girth numbers are generated
The LGX works by controlled overfill. During each cycling session, the pump moves saline into the cylinders until the patient feels a firm, slightly taut erection — not a painful one. Repeated full inflation applies radial and axial stretch to the tunica albuginea and surrounding cavernosal tissue. Over months, this mechanical loading is thought to produce gradual tissue remodeling.
The published range for expansion-related gain is 1 to 3 cm in length and 0.5 to 1.5 cm in girth across 12 to 24 months. A 2021 review of inflatable prosthesis outcomes in the Journal of Sexual Medicine reported mean length gains of 1.6 cm at 12 months for LGX-type devices in men with adequate pre-surgical tissue. Men with Peyronie's disease or prior radical prostatectomy often show smaller gains, sometimes 0.5 to 1 cm, because scarred tissue resists stretch.
Girth expansion is more reliable than length expansion. Because the cylinders are paired and inflate laterally, circumferential recruitment happens even when longitudinal gain stalls. That asymmetry — girth easier than length — is the single most useful thing to understand before surgery.
Comparing the before and after states
| Parameter | Before implant (best erect) | 6 months after | 12 months after | 24 months after |
|---|---|---|---|---|
| Erect length (cm) | Baseline, often 11–15 | +0.5 to 1.5 | +1 to 2.5 | +1 to 3 |
| Erect girth (cm) | Baseline, often 10–12 | +0.3 to 0.8 | +0.5 to 1.2 | +0.5 to 1.5 |
| Rigidity | Variable, often insufficient | High, on demand | High, on demand | High, on demand |
| Reliability | Unpredictable | 95%+ mechanical survival at 5 years | Same | Same |
| Spontaneity | Depends on PDE5 drugs | Requires pumping | Requires pumping | Requires pumping |
The rigidity row deserves emphasis. The LGX does not restore spontaneous erections, and it does not restore sensation in the glans — that remains intact because the dorsal nerve is spared. What changes is reliability: the 5-year mechanical survival rate for modern three-piece inflatables is roughly 85 to 95 percent in registry data, per the 2018AUA guideline on erectile dysfunction.
The real before-and-after timeline
| Phase | Timeframe | What happens | Typical measurement |
|---|---|---|---|
| Pre-op baseline | 2–4 weeks before | Stretched flaccid and best erect length recorded | Baseline locked |
| Surgery and early healing | Days 0–14 | Device left partially inflated; swelling resolves | Not measured |
| First activation | Day 14–21 | Patient taught to cycle the pump | Unreliable, painful |
| Early cycling | Weeks 3–12 | Daily full inflation, 10–15 minutes | Gradual gain begins |
| Consolidation | Months 3–12 | Tissue remodeling continues | +1 to 2.5 cm length |
| Plateau | Months 12–24 | Gains slow, girth stabilizes | Final range reached |
The 14 to 21 day activation window is not arbitrary. Earlier inflation risks wound dehiscence and cylinder migration. Later activation allows capsule formation that resists expansion. Surgeons who activate at day 7 in selected patients report slightly better early length, but the evidence for that is weak and device-specific.
Why some men see more gain than others
Three variables dominate the outcome, and none of them is the device itself. First is pre-surgical corporal tissue health: men with viable smooth muscle and minimal fibrosis expand more. Second is cycling discipline — studies consistently show that men who inflate fully once daily for 10 to 15 minutes gain more than men who cycle sporadically. Third is baseline geometry: a shorter, wider penis tends to gain girth; a longer, thinner one tends to gain length.
A non-obvious detail: the "before" measurement that matters most is the stretched flaccid length taken under anesthesia, not the erect length at home. Anesthesia eliminates sympathetic tone, and the difference between office stretch and anesthetized stretch can be 1 to 2 cm. Surgeons use the anesthetized value to select cylinder length, so a man whose home measurement looks disappointing may still get a good outcome.
Correcting common misconceptions
The most persistent myth is that the LGX grows the penis. It does not grow new tissue. It restores lost erectile volume and recruits a modest amount of existing tissue through expansion.
The second myth is that a bigger implant means a bigger result. Oversized cylinders cause pain, erosion, and revision, and they do not improve final length. Proper sizing is conservative.
The third myth is that gains are permanent if the device is removed. They are not. Expansion-related gains depend on continued cycling and the device being in place. If the implant is explanted, tissue returns toward its pre-implant state within 6 to 12 months.
Practical steps that actually improve the before-and-after result
- Get an anesthetized stretched measurement before committing; it defines the ceiling.
- Cycle fully once daily starting at the activation visit, 10 to 15 minutes per session.
- Follow the surgeon's inflation pressure guidance rather than pumping until pain.
- Keep body weight stable; a 10 lb gain increases suprapubic fat and hides 0.5 to 1 cm of visible length.
- Attend the 3-month and 12-month sizing reviews; early revision for undersizing is easier than late.
- Report persistent pain at full inflation — it can signal cylinder oversizing or erosion.
Red flags that warrant immediate contact with the surgeon:
- Fever above 101°F or wound drainage in the first 30 days.
- New curvature or a "hinge" sensation during inflation.
- Loss of the pump to the scrotum or inability to deflate.
- Pain that persists more than 10 minutes after deflation.
Limits of the evidence and what to expect honestly
The before-and-after literature for the LGX is smaller and less rigorous than marketing implies. Most series are single-surgeon, retrospective, and lack a control group. The 1 to 3 cm length range is consistent across series but the upper end reflects men with favorable baseline tissue. A 2023 systematic review found that patient-reported satisfaction was high — above 85 percent — even when measured gains were at the low end, because reliability mattered more than size.
Per the 2018 AUA guideline, penile prosthesis is a treatment for erectile dysfunction refractory to conservative therapy, not a cosmetic procedure, and patient counseling on realistic expectations is a required step. That counseling is where the honest before-and-after conversation belongs.