Penile traction has been studied for elective lengthening, Peyronie’s disease and recovery after penile or prostate surgery. Below, we break down how each study was conducted, what the researchers measured and what the results actually tell us. Every study links to its original publication.
What the evidence indicates
The research points to a clear distinction. Traction has produced measurable increases in penile length across multiple clinical studies. The best controlled evidence comes from treatment of Peyronie’s disease and postoperative rehabilitation. Elective-lengthening studies also report gains, but most lack untreated control groups. Penile girth is a separate question, and these studies do not show consistent shaft-girth increases.
Vacuum therapy should not be lumped together with traction. Pumps can create temporary expansion, but the six-month vacuum study reviewed here did not find a statistically significant increase in stretched penile length.
Traction for Elective Lengthening
These studies followed men who wanted more penile length without surgery. All three reported increases with sustained traction. The main limitation is straightforward: without randomized control groups, we can report the measured gains but cannot treat them as guaranteed results for everyone.
Pilot study of an extender for perceived short penile length
Gontero et al. (2009) | Prospective, single-arm study
Methodology: Twenty-one men enrolled in a six-month prospective pilot study; 16 completed follow-up. They wore a penile extender for at least four hours per day. Researchers measured flaccid and stretched length before and after treatment.
Results: Average flaccid length increased by 2.3 cm and stretched length by 1.7 cm after six months. Shaft girth did not change significantly.
Takeaway: Consistent traction was followed by meaningful length gains in the men who completed the study. The study was small and had no control group, so its averages are not a promise of what every user will achieve.
Read original study (PubMed) · DOI
Changes in penile length after three months of extender use
Nikoobakht et al. (2011) | Prospective, single-arm study; 23 participants
Methodology: Researchers followed 23 men using an extender for three months. Daily wear began at four to six hours and increased toward nine hours. They tracked flaccid length, stretched length and circumference.
Results: Flaccid length increased from 8.8 to 10.5 cm, and stretched length from 11.5 to 13.2 cm. Both represent average gains of 1.7 cm.
Takeaway: The measurements show increased length after three months of intensive traction. There was no significant increase in proximal shaft circumference, although a small glans-circumference increase was reported. This study also had no untreated control group.
Read original study (PubMed) · DOI
Traction outcomes after psychosexual counseling
Nowroozi et al. (2015) | Prospective observational study; 54 traction users
Methodology: Of 163 men seeking enlargement who received counseling, 54 chose traction. They used an extender four to six hours per day for six months. Length measurements were repeated three months after treatment stopped.
Results: Average gains were 1.7 cm flaccid, 1.3 cm stretched and 1.2 cm erect length. Those gains were maintained at the nine-month assessment; shaft-girth increases were not established.
Takeaway: This study matters because it measured erect length and checked whether gains lasted after the device was discontinued. They did in the men followed. Participants selected their own treatment, however, and satisfaction was mixed.
Read original study (PubMed) · DOI
Traction in Peyronie’s Disease
Peyronie’s disease can bend the penis and reduce its length as scar tissue develops. Traction studies in this population measure two distinct goals: recovering length and reducing curvature. The stronger trials show benefits for both, although the size of the effect depends on the device and protocol.
Traction in stable Peyronie’s disease
Gontero et al. (2009) | Prospective phase II study; 15 completed
Methodology: Men with stable Peyronie’s disease used a traction device for at least five hours daily over six months. Fifteen completed the prospective study. Researchers tracked penile length and curvature.
Results: Stretched length increased by 1.3 cm and flaccid length by 0.83 cm on average. Curvature decreased from 31° to 27°, but that change was not statistically significant (p = 0.056).
Takeaway: There were measurable length gains despite the presence of Peyronie’s disease. Curvature is another matter: this trial did not demonstrate a statistically significant correction. Lengthening and straightening should not be treated as the same result.
Read original study (PubMed) · DOI
Early traction during the active phase of Peyronie’s disease
Martínez-Salamanca et al. (2014) | Prospective, nonrandomized controlled study; 55 treated, 41 untreated
Methodology: Researchers compared 55 men treated with traction for six months against 41 men who received no treatment during the early phase of Peyronie’s disease. The study was prospective and controlled, but treatment groups were not randomized.
Results: Average curvature in the traction group fell from about 33° to 15° after six months. The untreated group generally experienced worsening curvature and a loss of stretched length.
Takeaway: The contrast between the treated and untreated groups is substantial. Traction was associated with less deformity and better length preservation during active disease. Because the groups were not randomized, the study cannot eliminate all differences between the men who received treatment and those who did not.
Read original study (PubMed) · DOI
Short-duration traction with RestoreX
Ziegelmann et al. (2019) | Randomized controlled trial; 110 participants
Methodology: In a randomized controlled trial, 110 men with Peyronie’s disease were assigned three to one to RestoreX traction or no therapy. The treatment group used the device for 30 to 90 minutes daily for three months.
Results: Average length increased by 1.5 cm with traction versus 0 cm in controls. Curvature improved by 11.7° with traction while worsening by 1.3° in controls.
Takeaway: This is one of the strongest comparisons on the page. Traction outperformed no treatment for both length and curvature, using a shorter daily schedule than traditional extenders. These are results in men with Peyronie’s disease, not a direct trial of elective enlargement.
Read original study (PubMed) · DOI
Six-month outcomes and follow-up of the RestoreX trial
Joseph et al. (2020) | Open-label extension and follow-up of the 2019 randomized trial
Methodology: This publication followed participants from the earlier RestoreX trial into an open-label extension. Sixty-four had measurements at six months. The analysis included men who used traction for at least 15 minutes per day.
Results: Among regular users, reported length increases averaged roughly 2.0–2.3 cm by six months, alongside additional improvements in curvature.
Takeaway: Longer treatment was followed by additional gains. The distinction is that this is an extension of the same trial, not a second randomized trial. Adherence and loss to follow-up matter when comparing these results with the original three-month findings.
Read original study (PubMed) · DOI
Traction Following Penile or Prostate Surgery
After prostate or penile surgery, the problem is often preventing or recovering lost length rather than enlarging an unaffected penis. These studies test whether mechanical rehabilitation can help. Their results matter for postoperative care and should be interpreted in that setting.
Combined traction and vacuum therapy before prosthesis revision
Chung et al. (2011) | Single-patient case report
Methodology: A single patient used vacuum therapy alongside approximately eight hours of daily traction for eight months before undergoing penile-prosthesis revision. Researchers documented length before treatment and after revision.
Results: Stretched length increased by 2.3 cm before revision. After surgery, measured erect length was 4.4 cm greater than before treatment.
Takeaway: The case shows the extent of change achieved in one postoperative situation. It does not show that traction alone produced all of the improvement; vacuum treatment and later surgery were also involved. A single case should not be used as an estimate of typical results.
Read original study (PubMed) · DOI
Randomized trial of traction after radical prostatectomy
Toussi et al. (2021) | Single-center randomized controlled trial; 82 randomized
Methodology: In a single-center randomized study after radical prostatectomy, 82 men were assigned to traction-based rehabilitation or a control group. Fifty-five completed six-month outcome measurements.
Results: Stretched length changed by approximately +1.6 cm with traction versus +0.3 cm in controls at six months. The traction group also reported better erectile-function and satisfaction outcomes.
Takeaway: The randomized comparison favors traction as part of rehabilitation after prostate surgery. It addresses postoperative length and function, not cosmetic enlargement. Follow-up was incomplete, so the results should be read with that in mind.
Read original study (PubMed) · DOI
Nine-month follow-up after prostatectomy
Zganjar et al. (2023) | Open-label and follow-up phase of the Toussi et al. trial
Methodology: Researchers reported nine-month follow-up from the postoperative trial, including an open-label phase in which treatment timing differed. Forty-five of the original 82 men had measurements at nine months.
Results: Early, sustained traction was associated with about +1.7 cm in length, compared with a 0.1 cm decrease without treatment. Men who started traction later showed smaller gains.
Takeaway: Early use performed better than delayed use in the observed follow-up. That is a relevant postoperative finding, but the crossover design and missing follow-up measurements make it less conclusive than the original randomized comparison.
Read original study (PubMed) · DOI
Vacuum Devices and Penile Length
Vacuum devices and traction devices work differently, and their lengthening evidence is not interchangeable. The study below tested whether a defined pumping schedule caused a lasting change in stretched length. Its results answer that question directly.
Vacuum treatment for penile elongation
Aghamir et al. (2006) | Prospective treatment study; 37 participants
Methodology: Thirty-seven men with stretched penile length below 10 cm underwent vacuum therapy for 20 minutes per session, three times per week, over six months. Researchers compared stretched length before and after the program.
Results: Average stretched length changed from 7.6 to 7.9 cm. The difference was not statistically significant.
Takeaway: This pumping regimen did not deliver a demonstrated permanent length increase. That does not erase the other clinical uses of vacuum devices, but temporary expansion should not be presented as proven lasting growth.
Read original study (PubMed) · DOI
How to interpret these findings
Read these findings for what they measured. Flaccid, stretched and erect length are different outcomes; an improvement in one does not automatically establish the same change in another. A controlled study carries more weight than an uncontrolled study or a case report. Results in Peyronie’s disease and postoperative recovery also cannot be transferred directly to healthy men seeking elective enlargement.
This page explains the published evidence; it is not a personal treatment plan. For Peyronie’s disease, recovery after surgery or erectile dysfunction, decisions about devices should be made with a qualified clinician.
Related PMP resources: Penile extenders · Penis pumps · Educational articles
