Manually stretching the penis may do more harm than good, but there's evidence penile traction therapy (PTT) may have positive outcomes for some people with Peyronie's disease. PTT involves a device that gently straightens a curved penis. In a 2019 study of one such device used twice a day for 20 minutes at a stretch, 94% of men regained an average of 1.6 centimeters in penis length, 77% had an improvement in curvature of around 17 degrees, and 80% of those who weren't able to have penetrative sex prior to treatment were able to after 12 weeks.