How effective is VED therapy for penile length preservation after radical prostatectomy in randomized human trials?

1. What the randomized trials actually found about length — shrinkage prevented but function not restored

Two of the better‑known randomized trials reported no significant improvement in spontaneous erections with early VED use but did report clear benefits for penile size preservation: Raina et al. (109 men) found no advantage for spontaneous erectile recovery yet demonstrated statistically significant preservation of penile length, and Kohler’s trial also failed to show improved erectile recovery while showing less length loss with early VED use versus delayed or no use ^{[1] [4]}.

2. How systematic reviews and meta‑analyses synthesize those trials

Multiple systematic reviews and at least one meta‑analysis conclude that early VED therapy is associated with preserved stretched penile length compared with observation or delayed treatment, and that combining VED with PDE‑5 inhibitors sometimes improves subjective measures and compliance; nonetheless authors uniformly flag that RCTs are few, small and heterogeneous, limiting strength of inference ^{[2] [5] [6]}.

3. Why preservation of length is biologically plausible (preclinical support)

Basic science and animal models support a plausible mechanism: VED increases arterial inflow, reduces cavernosal hypoxia and markers of fibrosis, and preserves smooth muscle and endothelial integrity after cavernous nerve injury—mechanistic data that align with the clinical signal for size preservation even when erectile recovery is not demonstrably improved in RCTs ^{[7] [3] [6]}.

4. What weakens confidence in the RCT evidence

Confidence is blunted by small sample sizes (many trials include tens, not hundreds, of patients), divergent VED schedules (daily minutes, timing after catheter removal, use or not of constriction rings), variable concomitant therapies (PDE‑5 inhibitors in some arms), and short follow‑up durations; systematic reviews and narrative reviews repeatedly call for well‑designed, multicenter randomized studies with long‑term follow‑up to settle effect size and durability ^{[8] [9] [2]}.

5. Patient adherence, tolerability and real‑world impact

Adherence rates in studies vary but can be high in motivated cohorts (one earlier series reported 80% initial compliance), and combined regimens (VED + PDE‑5i) sometimes improved compliance and subjective hardness scores; nonetheless real‑world effectiveness depends on adherence, patient selection (nerve‑sparing status and baseline function), and expectations about function versus length outcomes ^{[10] [8] [11]}.

6. Bottom line for clinicians and patients — a qualified endorsement for length preservation

Randomized human trials and pooled reviews consistently show that early VED use after radical prostatectomy preserves stretched penile length better than observation or delayed therapy, even though restoration of spontaneous erectile function is not reliably improved in those RCTs; given the mechanistic support and low invasiveness, VED can be recommended as a reasonable intervention to reduce post‑operative penile shortening while acknowledging the evidence is limited and that definitive large RCTs are lacking ^{[1] [7] [2] [3]}.

7. Alternative perspectives and research gaps

Some nonrandomized studies and individual trials report mixed or null findings on length at certain time points and emphasize natural postoperative fluctuations in stretched length, underscoring heterogeneity in outcomes; major gaps remain in optimal timing, frequency, use with adjunctive drugs, and long‑term functional versus cosmetic outcomes—questions that existing systematic reviews explicitly call out ^{[12] [5] [9]}.