Men who wear a device meant to extend their penises saw growth of up to 33 percent over six months, according to a new study.

The Italian study followed 21 men for up to a year as they used a device with dynamic rods. They wore it for an average of five hours in the first month, five hours in the third month and four hours in the sixth month.

Urologist Dr. Paolo Gontero said the average flaccid length at the start was 2.82 inches. After a year, it was 3.72 inches, though there was no increase in girth.

He said erectile function scores also improved during the test.

Gontero also said that surgeries to increase the size of the penis have high risks of complication and dissatisfaction. And only one of the men in the study would have been eligible for surgery under American guidelines.

"If these results are confirmed by further research, we propose that the device should be used as a first-line treatment option for men seeking a penile lengthening procedure," he said.

The results were published in the March issue of BJU International.