What clinical trials have tested penile traction devices and what were their protocols and outcomes?
Executive summary
Randomized and nonrandomized clinical trials of penile traction therapy (PTT) have tested several devices and protocols—most prominently the RestoreX device—in men with Peyronie’s disease and in the post‑prostatectomy setting, reporting consistent gains in stretched penile length, reductions in curvature and generally minimal adverse events, but with important limitations in trial size, duration, and potential conflicts of interest [1] [2] [3] [4].
1. The pivotal randomized trial in Peyronie’s disease: RestoreX, 30–90 minutes daily
A randomized, single‑blind, controlled trial (ClinicalTrials.gov NCT03389854) assigned 110 men with Peyronie’s disease 3:1 to RestoreX traction for 30–90 minutes per day versus no therapy for three months and measured safety as the primary outcome with penile length, curvature and questionnaires as secondary outcomes; investigators reported that daily use was safe and produced statistically and clinically meaningful improvements in curvature, length and some erectile function measures with no significant adverse events in the randomized phase [5] [1].
2. Open‑label and follow‑up data from the RestoreX trial
Follow‑up and open‑label phases of the same RestoreX study extended outcomes reporting beyond three months and reinforced earlier findings: the study cohort showed sustained improvements in penile curvature and length and continued low rates of device‑related complications, with device provision supported in part by PathRight Medical and Mayo Clinic funds and inventor involvement disclosed in the publication [2] [6].
3. Post‑prostatectomy randomized controlled data: short daily sessions preserve length and function
A single‑center randomized trial in men after radical prostatectomy tested two RestoreX protocols (approximately 30 minutes five times weekly versus 60 minutes seven times weekly for about five to six months) against control and found greater preservation/improvement of stretched penile length (+1.6 versus +0.3 cm) and better International Index of Erectile Function (IIEF) scores in traction groups at six months, with lower use of intracavernosal injections among PTT users; these outcomes suggest a potential role for brief daily traction in penile rehabilitation [7] [3] [8].
4. Earlier and adjunctive studies: longer traction protocols, pilot cohorts, and combination therapy
Before RestoreX, pilot and prospective cohorts used other extenders with longer recommended daily wear (commonly 2–8 hours per day, sometimes up to 9 hours), reporting length gains and curvature improvements in small samples—Levine’s 11‑patient pilot used 2 to 8 hours daily for six months with good tolerability—and nonrandomized studies have evaluated traction as an adjunct to intralesional injections with greater curvature correction when combined [9] [10] [11].
5. Quantifying outcomes across studies and systematic reviews
Narrative reviews and systematic syntheses report fairly consistent effect sizes: mean curvature reductions around 20–25 degrees and mean stretched penile length gains approaching ~1.5–2.0 cm in many series, with parallel improvements in patient satisfaction and erectile measures when reported; however effect sizes vary by device, daily duration, and whether traction is combined with injections [4] [10] [12].
6. Safety, adherence challenges, and sources of bias
Across trials adverse events were generally mild—transient pain and erythema were reported in a minority, and few subjects discontinued for intolerance—yet practical adherence to multi‑hour daily protocols has been a recurrent problem and may bias results toward motivated users; additionally, several leading trials disclose industry support or inventor involvement (eg, device provided by PathRight, inventor Landon Trost listed) and single‑center designs limit generalizability, underscoring the need to interpret reported benefits with caution [11] [2] [9].
7. Bottom line and research gaps
Randomized controlled data—most robustly for the RestoreX device—support that relatively short daily traction (30–90 minutes) can be safe and produce clinically meaningful improvements in penile length and curvature in Peyronie’s disease and preserve length and some erectile metrics after prostatectomy, but heterogeneity of devices, protocols, study sizes, follow‑up duration and potential conflicts mean multicenter, independently funded trials with standardized adherence measures and longer durability data are still required to cement clinical recommendations [1] [3] [4].