An erection is a vascular event that depends on healthy arteries, intact nerves, a sealed tunica and adequate testosterone. Erectile dysfunction happens when one of those links fails, and the failing link determines the treatment. This article sets out the mechanisms, the order in which treatments should be tried, and the point at which a penile implant becomes the honest recommendation.
The short version
- Erectile dysfunction is usually vascular: the small arteries that fill the erectile bodies stop delivering enough blood, most often for the same reasons that damage arteries elsewhere in the body.
- The mechanism matters more than the label. Nerve damage after prostate surgery, venous leak through a scarred tunica and low testosterone all present as “ED” and all respond differently.
- Tablets fail in roughly three of ten men overall, and far more often in long-standing diabetes or after radical prostatectomy — but a large share of “failures” are really untried or badly instructed doses.
- A penile implant becomes the right answer when tablets and injections have been genuinely optimised and no longer produce a usable erection, not when they have merely been disappointing once.
- Because implant surgery permanently alters the erectile tissue, the sequence is not negotiable: exhaust the reversible options first, then operate.
What has to work for an erection to happen
An erection is a plumbing event with a neurological trigger. Sexual stimulation — physical, visual or imagined — releases nitric oxide from nerve endings inside the two erectile bodies that run along the penis, the corpora cavernosa. Nitric oxide raises a signalling molecule called cyclic GMP, the smooth muscle lining the arteries relaxes, and blood floods into thousands of sponge-like spaces at up to eight times the resting rate.
As those spaces expand they press the draining veins flat against the tough outer envelope of the erectile bodies, the tunica albuginea. That compression is what traps the blood in. An erection is therefore not simply a matter of pumping blood in; it depends just as much on sealing it there. Rigidity is maintained until an enzyme called PDE5 breaks the cyclic GMP down, the smooth muscle contracts again, and the blood drains away.
Four things must hold for that sequence to complete: arteries capable of delivering the inflow, nerves capable of carrying the signal, a tunica capable of sealing the outflow, and enough testosterone for desire and for the tissue itself to stay healthy. Erectile dysfunction is what you see when any one of them fails — which is why “erectile dysfunction” is a symptom rather than a diagnosis, and why the first job of a consultation is to work out which link has broken.
The six mechanisms behind erectile dysfunction
Most men have more than one of these running at once — a diabetic smoker in his sixties on a beta blocker has three. Identifying the dominant mechanism is what makes a treatment plan rational rather than a sequence of guesses.
| Mechanism | What is going wrong | Typical history | What usually helps |
|---|---|---|---|
| Arterial (vasculogenic) | Atherosclerosis and endothelial dysfunction narrow the cavernosal arteries, so inflow is too slow and too small to fill the erectile bodies. | Gradual onset over years, worse with exertion, alongside high blood pressure, high cholesterol, smoking or a known cardiac history. | Risk-factor treatment plus tablets early on; injections or an implant once the tissue no longer responds. |
| Neurogenic | The signal never arrives. The cavernous nerves are cut, stretched or irradiated, or the spinal pathway is interrupted. | Radical prostatectomy, radical cystectomy, rectal surgery, pelvic radiotherapy, spinal cord injury, multiple sclerosis. | Rehabilitation for 18–24 months; injections work well early, an implant where recovery plateaus. |
| Venous leak (cavernosal insufficiency) | Blood enters but is not held: the tunica or the smooth muscle cannot compress the outflow veins, so rigidity fades within seconds or minutes. | An erection that starts and then collapses, often lost on changing position, common with long-standing diabetes and after priapism. | Tablets often disappoint; this is one of the clearest indications for an implant. |
| Structural | The mechanics are distorted — plaque in the tunica, curvature, hourglass narrowing or extensive corporal fibrosis. | Palpable plaque, a bend that appeared over months, pain on erection, or a previously removed device. | Curvature correction where erections are otherwise strong; implant where curvature and failure coexist. |
| Endocrine | Low testosterone reduces desire, nocturnal erections and the health of the erectile tissue itself. Thyroid disease and high prolactin do the same by other routes. | Loss of morning erections and libido together, fatigue, reduced muscle mass, sometimes gynaecomastia. | Confirm with two morning blood tests; correcting the deficiency restores response to tablets in many men. |
| Drug-induced and psychogenic | Medication blocks the pathway, or performance anxiety and depression override it. Neither has damaged the tissue. | Sudden onset traceable to a new drug or a life event; erections still good on waking, alone, or with a different partner. | Medication review, psychosexual therapy, short-term tablets. Surgery is contraindicated here. |
Beta blockers, thiazide diuretics, SSRIs, finasteride, some antipsychotics and opioids are the medication groups most often responsible. A drug that arrived in the same month the problem did deserves scrutiny before anything else is considered.
Erectile dysfunction as an early warning
The cavernosal arteries are around 0.5 mm wide — narrower than the coronary arteries that supply the heart. When the endothelium, the single-cell lining shared by every artery in the body, begins to fail, the narrowest vessels announce it first. That is why new-onset vasculogenic erectile dysfunction in a man in his forties or fifties is treated in good urology practice as a cardiovascular finding, not merely a sexual one.
Published cohorts have repeatedly shown erectile dysfunction preceding a cardiac event by roughly three to five years. This is genuinely useful information: it means the symptom brings men into a clinic at a point where blood pressure, lipids, glucose and smoking can still be dealt with. Anyone we assess for erectile dysfunction has those parameters checked, and where they are abnormal we say so plainly and write to the family doctor.
It also has a bearing on surgical planning. Men who arrive asking about an implant are frequently men with untreated metabolic disease, and both the safety of an anaesthetic and the risk of a device infection improve materially when that disease is controlled first.
The treatment ladder, in the order it should actually be climbed
International guidance is consistent on the sequence. Each rung is less invasive than the one above it, and skipping upward is only justified when the rung below has genuinely been tried.
- Fix what is fixable. Stop smoking, treat hypertension and lipids, get HbA1c down, review every drug on the list, correct confirmed testosterone deficiency, and treat sleep apnoea. A meaningful minority of men need nothing further.
- PDE5 inhibitor tablets, properly used. Sildenafil, tadalafil, vardenafil or avanafil at full dose, with sexual stimulation, on an empty stomach where the drug requires it, across at least six to eight attempts before the drug is called a failure. Daily low-dose tadalafil suits men who dislike planning.
- Combination and mechanical options. A vacuum erection device, a constriction ring, or a tablet combined with a vacuum device. Unglamorous, inexpensive, and effective for a proportion of men who want to avoid needles.
- Intracavernosal injection therapy. Alprostadil alone or as a bi-mix or tri-mix, injected into the erectile body. It bypasses the nerve signal entirely, which is why it works after prostatectomy when tablets do not. Response rates are high; long-term persistence is not, because many men simply tire of it.
- Penile implant surgery. A device placed inside the erectile bodies to restore rigidity mechanically. It is the last rung because it is irreversible — and, for men who reach it, the one with the highest satisfaction of anything on the ladder.
When an implant becomes the right answer
The question is not how severe the erectile dysfunction feels. It is whether the reversible options have been exhausted, whether the tissue can still respond at all, and whether expectations match what a device actually does.
An implant is usually the honest recommendation when
- Full-dose tablets from at least two different molecules no longer produce an erection firm enough for penetration
- Injections work poorly, hurt, cause scarring, or have become an unacceptable routine after a genuine trial
- Erectile dysfunction followed radical prostatectomy or pelvic radiotherapy and has not recovered after 18–24 months
- Long-standing diabetes has caused irreversible small-vessel and nerve damage, and Doppler confirms poor inflow or venous leak
- Peyronie’s disease has produced both curvature and erectile failure, so one operation can address both
- Corporal fibrosis has followed priapism, infection or a removed device, and no medical option can work through scar tissue
- You want spontaneity and reliability rather than dosing, timing and hoping
We will delay or decline surgery when
- Tablets have never been taken correctly, or only two or three times, or without sexual stimulation
- Morning and nocturnal erections are still present and good — that points to a psychogenic or situational cause
- Testosterone deficiency, thyroid disease or a culprit medication has not yet been addressed
- HbA1c is above roughly 8.5%, because glycaemic control at that level sharply increases device infection risk
- An active urinary, skin or dental infection is present; every bacterial source must be cleared before a device goes in
- The hope is for extra length or girth — an implant restores rigidity, it does not enlarge
- The distress is driven by body image rather than by function
Four signs you have reached the top of the ladder
Men often wait years longer than they need to, mostly because nobody has told them what the end of medical treatment looks like. These are the practical markers.
The dose has nowhere left to go
You are on the maximum licensed dose of a PDE5 inhibitor, you have tried a second molecule, and the result is an erection that is better than nothing but not usable for intercourse.
Injections have become the price of sex
Injections still work, but the needle, the planning, the bruising or the ache have made intimacy an event you dread rather than want. Efficacy is not the only outcome that counts.
The erection will not stay
You can achieve an erection but lose it within a minute or two, or on changing position. That pattern suggests venous leak, and it is the pattern medication addresses least well.
Avoidance has replaced attempts
You have stopped initiating. When the sexual relationship has been organised around avoiding failure for a year or more, the reversible options have effectively been answered.
What a proper assessment involves
A useful erectile dysfunction workup is short and specific. A validated questionnaire such as the IIEF-5 puts a number on severity. Blood tests cover fasting glucose or HbA1c, lipids, and morning total testosterone repeated on a second day if low. Blood pressure, waist circumference and a medication review take five minutes and change management more often than anything else.
Where surgery is being contemplated, a penile duplex Doppler ultrasound after an intracavernosal test dose distinguishes arterial insufficiency from venous leak and documents how the tissue responds when the drug is delivered directly. That single test frequently settles the question of whether more medical treatment is worth attempting — and it is the investigation most often missing when men arrive after years of unsuccessful tablets.
You do not need to fly anywhere for the first step. Send your history, medication list, operative reports and recent blood results through our case review form and a urologist will tell you which mechanism your history points to, which rung of the ladder you are actually on, and whether an implant is warranted yet. We regularly reply that it is not.
Questions we are asked
Can erectile dysfunction be reversed, or is it permanent?
It depends entirely on the mechanism. Drug-induced, hormonal, psychogenic and early vasculogenic erectile dysfunction can all improve substantially, sometimes completely, when the cause is treated. Erectile dysfunction caused by cut nerves, extensive fibrosis or established venous leak does not reverse, because the tissue itself has changed. That distinction is what a proper assessment establishes, and it is worth establishing before anyone talks about surgery.
At what age does erectile dysfunction usually start?
Prevalence rises steadily with age — roughly a tenth of men in their forties and around half of men in their seventies report some degree of it — but age alone is a poor predictor. A healthy seventy-year-old often has better erectile function than a diabetic smoker of forty-five. Onset before fifty should always prompt a cardiovascular and metabolic check rather than a prescription alone.
How long should I try tablets and injections before considering an implant?
Give a tablet at full dose at least six to eight properly conducted attempts before judging it, and try a second molecule before abandoning the class. If injections are appropriate, judge them over a few months of real-world use, not a single clinic test dose. Where erectile dysfunction follows prostate surgery, allow 18 to 24 months of rehabilitation before treating the result as final. Beyond that, waiting longer rarely changes the outcome.
Does an implant fix the underlying disease?
No, and that is worth being clear about. An implant restores erections mechanically; it does nothing for the diabetes, hypertension or arterial disease underneath. Those still need treating for your general health, and controlling them before surgery also lowers the risk of device infection.
Will a urologist tell me if I am not ready for surgery?
A good one will, and we do it routinely. We decline or postpone cases where medication has never been optimised, where nocturnal erections are preserved, where diabetic control makes infection likely, and where the expectation is enlargement rather than rigidity. Turning down unsuitable cases is the only way published satisfaction figures stay meaningful.
Written and clinically reviewed by the Santa Urology surgical team, last reviewed . This article describes typical findings reported in the surgical literature and in our own practice; individual cases vary and nothing here is a substitute for a personal consultation. See our medical disclaimer.