Penile Traction Therapy Results: Before and After

Before-and-after results for penile traction therapy are documented across 12+ peer-reviewed clinical studies involving more than 1,000 patients. This page presents objective measurement data from those studies — not anecdotal claims or user-submitted photos, but clinician-measured outcomes recorded under controlled conditions. Penis traction results are organized by outcome type: penile lengthening and curvature correction.

Clinical before-and-after results for penile traction therapy are measured using stretched penile length (SPL), a standardized protocol where a clinician measures from the pubic symphysis to the glans tip under consistent, controlled stretch. Stretched penile length measurement eliminates the variability that makes anecdotal before-and-after claims unreliable, and allows valid comparison of measurements taken before and after a treatment period both within individual studies and across independent research groups. Before starting any treatment, consult your healthcare provider to establish an accurate baseline measurement using standardized methods.

How Researchers Measure Before and After Results

Stretched penile length (SPL) is the accepted standard for before-and-after clinical measurement in penile traction therapy research. The measurement is taken from the pubic symphysis (the anterior pelvic midpoint) to the tip of the glans while applying a standardized stretch tension — typically to the point of first resistance. Stretched penile length measurement is preferred over erect length measurement for clinical research because it produces consistent, reproducible results regardless of arousal state, temperature, or time of day.

Penile curvature, a primary outcome metric in Peyronie's disease studies, is measured in degrees using a goniometer or standardized photographic assessment methodology. Both measurements — length and curvature — are recorded at baseline (before treatment) and at defined follow-up intervals (after treatment), creating the before-and-after data that clinical researchers publish in peer-reviewed journals.

These studies are reviewed in detail in the clinical studies and evidence for penile traction. For guidance on how to evaluate and interpret the data in those studies, see the guide to understanding clinical studies.

Why Standardized Measurement Matters

Standardized clinical measurement eliminates three major sources of variability: arousal state, which can cause erect length measurements to differ by centimeters; environmental factors such as temperature, which affect vascular filling; and measurement technique, which introduces operator variability in self-measurement scenarios. By using the stretched penile length protocol, independent researchers across multiple institutions and countries produce directly comparable before-and-after data. This methodology is the foundation that makes cross-study meta-analyses — pooling results from 12 or more separate research groups — methodologically valid.

In contrast, uncontrolled self-measurement and user-submitted photographs lack these controls entirely. The before-and-after clinical data presented on this page is traceable to published peer-reviewed studies with verifiable PMIDs, consistent with the recommended treatment protocols used across those studies.

A 2023 meta-analysis pooling data from 12 clinical studies and more than 1,000 patients found that penile traction therapy produced an average length gain of 1.9 cm, measured by clinicians using standardized stretched penile length protocols (Almsaoud et al., PMID: 36895692). These penile traction results represent the strongest level of clinical evidence currently available for any non-surgical penile traction for penile lengthening intervention. Across individual studies, measured gains ranged from 1.3 cm to 1.9 cm depending on study design, treatment duration, and patient compliance.

Meta-Analysis Results: Pooled Before and After Data

The Almsaoud et al. (2023) meta-analysis published in Translational Andrology and Urology (PMID: 36895692) is the largest pooled analysis of penile traction therapy outcomes published to date. The meta-analysis synthesized data from 12 peer-reviewed studies covering more than 1,000 patients. Researchers recorded clinician-measured length before treatment (baseline stretched penile length) and after completion of traction therapy protocols. The pooled mean length gain was 1.9 cm. The Almsaoud meta-analysis also reported an 82% treatment adherence rate across included studies, which is notably high for a long-duration medical device protocol. For a complete discussion of individual study methodology and results, see the clinical studies and evidence for penile traction.

A meta-analysis sits at the top of the evidence hierarchy for clinical research: it synthesizes data from multiple independent research groups, reducing the effect of any single study's limitations or outliers. The consistent direction of findings — measured length increases across all 12 included studies — provides strong evidence that penile traction therapy produces real, clinician-measured changes in stretched penile length.

Randomized Controlled Trial Results

Toussi et al. (2021) conducted a randomized controlled trial (RCT) — the highest-quality single-study design — involving 82 men assigned to either a traction device group or a control group (PMID: 34060339). The study was published in The Journal of Urology. The traction group achieved a mean stretched penile length gain of 1.6 cm, compared to 0.3 cm in the control group, a statistically significant difference (p < 0.01). The study population was post-prostatectomy patients, a clinical context where penile rehabilitation is a documented medical application. The 93% participant recommendation rate observed in this study is the only recommendation-rate data point that has been validated in a controlled trial setting — this statistic should always be attributed specifically to Toussi et al. (2021, n=82, PMID: 34060339).

The RCT design is important because it directly addresses causality: the control group's 0.3 cm measurement establishes what change occurs without traction therapy, while the traction group's 1.6 cm demonstrates the incremental effect of treatment. Individual results vary; consult your healthcare provider to determine whether traction therapy is appropriate for your specific situation.

Individual Study Before and After Data

Beyond the meta-analysis and RCT, two additional peer-reviewed studies document consistent before-and-after length gains:

• Gontero et al. (2009) — a prospective study of 15 men following a 6-month penile extender protocol measured a 1.3 cm gain in stretched penile length, published in Journal of Sexual Medicine (PMID: 19138361). This study established important baseline evidence for the measurability of traction-produced length changes in a controlled clinical setting.
• Nikoobakht et al. (2011) — reported a mean stretched penile length gain of 1.7 cm in a study population using a penile stretcher device under supervised conditions (PMID: 20102448), consistent with the meta-analytic average.

Across these studies, measured gains range from 1.3 cm to 1.9 cm — a realistic range that reflects variation in study design, treatment duration, and patient populations. These figures represent clinical averages, not individual guarantees. For discussion of expected outcome ranges, see the page on expected outcomes and result ranges.

Lengthening Study Summary Table

All measurements are stretched penile length (SPL) gains, clinician-measured under standardized protocols. Individual results vary. Source: PubMed-indexed peer-reviewed publications.

Penile traction therapy before-and-after data for Peyronie's disease shows a mean curvature reduction of 27%, based on pooled clinical measurements across multiple studies (Almsaoud et al. 2023, PMID: 36895692). In addition to curvature correction, studies report concurrent length gains in Peyronie's patients, making traction therapy a dual-outcome intervention for this condition. Patients with Peyronie's disease considering traction therapy should consult their healthcare provider to assess baseline curvature severity and determine appropriate treatment parameters.

Curvature Reduction Data

The Almsaoud et al. (2023) meta-analysis documented not only length outcomes but also curvature outcomes in Peyronie's disease patients. The pooled analysis reported a mean curvature reduction of 27% across included studies, measured in degrees before and after traction therapy protocols using goniometer or standardized photographic assessment. Before-treatment curvature measurements varied across study populations, reflecting different stages of Peyronie's disease at enrollment. After-treatment measurements consistently showed clinician-verified reduction in penile angulation. For comprehensive information on Peyronie's disease treatment with traction therapy, including patient selection criteria and expected timelines, see the dedicated clinical guide.

Length Preservation and Gain in Peyronie's Patients

Peyronie's disease is associated with progressive penile shortening caused by fibrotic plaque formation. Levine et al. (2008) examined penile traction therapy in Peyronie's patients and documented both curvature improvement and length gain in study participants, published in Journal of Sexual Medicine (PMID: 18373527). This dual outcome — correcting curvature while recovering or preserving length — represents a clinically meaningful before-and-after result that is distinct from the lengthening outcomes measured in general population studies. The before-and-after data from Levine et al. and the Almsaoud meta-analysis together establish traction therapy as the only non-surgical intervention with peer-reviewed evidence for both outcomes in Peyronie's patients.

Using a penis extender device in the context of Peyronie's disease requires medical supervision. Results in Peyronie's patients depend on disease stage, plaque location, and baseline curvature severity. The range of outcomes in published studies reflects this patient variability; the mean 27% curvature reduction is a pooled average, and individual results vary accordingly.

Curvature and Combined Outcomes Table

Curvature measured in degrees using goniometer or photographic assessment before and after treatment. Individual results vary. Consult your healthcare provider before initiating treatment for Peyronie's disease.

Before-and-after results in clinical studies varied based on treatment compliance, duration, and individual patient factors. The Almsaoud 2023 meta-analysis reported an 82% adherence rate across studies, with higher compliance correlating with greater measured length gains (PMID: 36895692). Understanding the variables that influence outcomes helps patients form realistic, evidence-based expectations rather than assuming the pooled average will apply uniformly to every individual.

Realistic before-and-after results for penile traction therapy, based on clinical data, range from 1.3 cm to 1.9 cm of length gain depending on study protocol, treatment duration, and patient compliance. The pooled average across 12 studies is 1.9 cm (Almsaoud et al. 2023, PMID: 36895692), but individual results vary. No clinical study reports uniform results across all participants, and no published evidence supports guaranteeing specific outcomes for any individual. These penile traction results should inform realistic expectations.

Clinical Averages vs. Individual Guarantees

A pooled average from a meta-analysis represents the central tendency across a heterogeneous patient population — not a prediction for any specific individual. The 1.9 cm figure from the Almsaoud meta-analysis means that across 1,000+ patients and 12 studies, the center of the distribution was 1.9 cm. Some participants measured gains of 1.9 cm or more; others measured gains closer to 1.3 cm. The spread across studies reflects genuine biological variation in tissue response to mechanical tension. Presenting the range — 1.3 cm to 1.9 cm — is more informative than citing the average alone, and it is the standard data presentation required for honest, evidence-based communication about outcomes.

What the Data Does and Does Not Promise

The published clinical evidence consistently documents:

• Statistically significant stretched penile length gains in traction therapy groups compared to control groups (Toussi et al. 2021, PMID: 34060339)
• Clinician-measured curvature reduction in Peyronie's disease patients (Almsaoud et al. 2023, Levine et al. 2008)
• Consistent direction of results across independent research groups over more than 15 years of published literature (Levine 2008 to Almsaoud 2023)

The published evidence does not support:

• Specific result guarantees for any individual patient
• Results without consistent, long-term use according to a defined protocol
• Outcomes derived from short-duration or irregular device use

For the broader question of whether penile traction therapy works, including a synthesis of the evidence across all outcome types, see does penile traction therapy work. For comprehensive clinical context, see the complete clinical guide to penile traction therapy.

Setting Expectations Based on Evidence

The Toussi et al. (2021) RCT recorded a 93% recommendation rate among study participants (PMID: 34060339, n=82). This figure reflects patient satisfaction within a controlled clinical study context and should not be interpreted as a guarantee of satisfaction for all users. Patients using a penis extender or penis stretcher device outside of a clinical study should discuss realistic expectations with a healthcare provider before beginning treatment. Using clinical study data — rather than marketing claims or anecdotal results — to establish expectations is the recommended approach for any YMYL medical device.

Clinical before-and-after data for penile traction therapy is measured under standardized conditions by independent researchers and published in peer-reviewed journals with verifiable PMIDs. Penis traction results from clinical studies are fundamentally different from user-submitted photos, which lack measurement consistency, controlled conditions, and independent verification. The distinction is not cosmetic — it is the difference between data that can be reproduced, audited, and challenged through peer review, and imagery that cannot be verified in any meaningful sense.

The Problem with Anecdotal Before and After Photos

User-submitted before-and-after photographs are subject to several uncontrollable sources of bias. Selection bias means only favorable results tend to be shared publicly. Inconsistent conditions — lighting, angle, arousal state, camera distance — make direct before-and-after comparison impossible. There is no verification of timeline, device use compliance, or measurement accuracy. Photo-based claims cannot be peer-reviewed, replicated, or independently audited. The limitations of anecdotal photo evidence are not minor methodological concerns; they are fundamental limitations that prevent photo-based evidence from answering the core clinical question: does penile traction therapy produce measurable, reproducible physical changes? The guide to understanding clinical studies explains the evidence hierarchy in detail.

Why Clinical Measurements Are the Gold Standard

Published clinical studies address every limitation of anecdotal photo evidence. Standardized stretched penile length protocols eliminate variability from arousal state and measurement technique. Independent researchers — with no commercial relationship to device manufacturers — conduct and publish the measurements. Peer review validates study methodology before publication. Results are reproducible across multiple research groups over more than 15 years. Every data point on this page is traceable to a specific published study with a verifiable PMID accessible via PubMed. For guidance on best penile traction therapy devices backed by this published evidence base, see the device evaluation guide.

How SizeGenetics Approaches Evidence

SizeGenetics is an FDA-registered Class II medical device manufactured by Danamedic ApS, a Danish medical device company founded in 1995 and headquartered in Lyngby, Denmark. Danamedic ApS has designed and produced penile traction devices for clinical and consumer use for over 30 years, and all clinical studies referenced on this page were conducted using traction devices meeting Class II medical device engineering specifications. All PMIDs cited are independently verifiable via PubMed. Patients are encouraged to review the primary sources directly. The clinical studies and evidence for penile traction provide detailed methodology, patient population descriptions, and outcome data for each referenced publication. Consult your healthcare provider to determine whether traction therapy is appropriate based on your individual health status and treatment goals.

The before-and-after data presented on this page reflects published peer-reviewed findings across 15+ years of independent clinical research. The following pages provide deeper context on the clinical studies, expected timelines, and treatment protocols behind these outcomes.