Update 10/20/2019: A new metastudy done by scietists from Italy and the UK reviewed several non-surgical and surgical approaches to increase penis size and evaluated their risks. The results are fully in line with out own and support the statement that penis surgery and almost all of the devices and pums sold for enlargement present a high risk and very limited results.
Some men seek injections of natural and synthetic fillers to increase the girth of the penis. Others seek surgery if a smaller penis size or penile abnormality (like hypospadias) is interfering with the ability to urinate or quality of life. Small penis size usually is not an indication for surgery to treat infertility. In such cases, assisted fertility procedures may be the better option.
Lengthening the penis. The most common procedure is to cut the ligament that connects the penis to the pelvic bone. This allows a little more of the shaft -- on average less than an inch -- to become visible outside the body. It's not really lengthening the penis so much as revealing more of what's usually hidden. To prevent the ligament from reattaching, a guy would need weights or stretching devices daily for about six months.