"The small bruise developed scarring in the penis and was then very difficult to treat," Paduch said.
In the more extreme cases, the urethra -- the tube that carries urine -- can be injured if a penile fracture is not treated.
Surgery is the only way to fix a broken penis and will almost always result in the man's regained sexual function. A recovery time of about six weeks is typical, said Paduch, before the patient can have sex again.
Sharlip, who also practices urology at the University of California San Francisco, said men who suffer from penile fractures are often in their 20s or 30s and are completely unaware of the injury.
"They come into the emergency room and they can't believe this has happened to them because they're young and healthy and very embarrassed," Sharlip said.
"It's important to remember this is a minor injury because it's repairable and that men can go completely back to normal after surgery."