Penile curvature can have different causes. Often the curvature is caused by a CC bigger than the other; in this case is hard to guess which method could correct curvature : it makes sense that stretching could correct a bit the degree of curvature; somebody suggests jelqing against the curve. Anyway, regular jelqing could make curve more pronounced, and this is even more probable with pumping (just my personal opinion).
Another cause of penis curves are fibrous plaques; in this case, gentle prolonged stretch is the best approach to correct curvature, IMHO, although it requires months or years and the degree of correction will be anyway not miracolous.
Adversely, stretching with high forces can make the curve worse.
About studies on extenders-curves, I found this:
"Penile Traction Therapy for Treatment of Peyronie’s Disease: A Single-Center Pilot Study
Laurence A. Levine, MD,* Mark Newell, PhD, † and Frederick L. Taylor, MD*
*Department of Urology, Rush University Medical Center, Chicago, IL, USA; † Medway Research Institute, North Augusta, SC, USA
Copyright © 2008 International Society for Sexual Medicine
ABSTRACT
Introduction. Peyronie’s disease (PD) is a fibrotic disorder of the penis whose etiopathophysiology remains unclear. At this time, there is no known reliable nonsurgical treatment. This study reviews our experience with external penile traction therapy to correct the deformity associated with this disorder. Aim. To evaluate prolonged external penile traction as a nonsurgical treatment for PD.
Methods.Ten men with PD completed this noncontrolled pilot study of traction therapy using the FastSize Penile Extender. Nearly all (90%) had failed prior medical therapy. Traction was applied as the only treatment for 2–8 hours/day for 6 months. All subjects underwent pre- and post-treatment physical examination including measurement of stretched flaccid penile length (SPL) and biothesiometry.
Main Outcome Measures. Curvature and girth were measured during erection before and after treatment with dynamic duplex ultrasound. Assessment of erectile and sexual function was further assessed with the International Index of Erectile Function and Quality of Life Specific to Male Erection Difficulties (QOL-MED) questionnaires. At 3 and 6 months post-treatment, SPL was measured and subjective assessment of deformity by the patient was recorded.
Results. Subjectively all men noted reduced curvature estimated at 10–40 degrees, increased penile length (1–2.5 cm) and enhanced girth in areas of indentation or narrowing. Objective measures demonstrated reduced curvature in all men from 10–45 degrees; average reduction for the group was 33% (51–34 degrees). SPL increased 0.5–2.0 cm and erect girth increased 0.5–1.0 cm with correction of hinge effect in four out of four men. International Index of Erectile Function-erectile function domain increased from 18.3–23.6 for the group. Changes in quality of life by QOL-MED were not found to be statistically significant in this small series. There were no adverse events including skin changes, ulcerations, hypoesthesia or diminished rigidity.
Conclusion. Prolonged daily external penile traction therapy is a new approach for the nonsurgical treatment of PD. Further study appears warranted given the response noted in this pilot study."
Link
A curved penis shouldn’t worry anyone, as long it doesn’t affect sexual intercourses. Many women find a curved penis more pleasurable and visually interesting - kinda "Wow, a penis with a character!".
:)
Edit: just seen is the same study linked by P-G.