After declining to reveal the nature of the surgery, which he described as "routine," Sparano added that it was uncertain whether Marshall would be ready for the start of training camp.
Marshall had hamstring and neck injuries last season in Denver, but he didn't miss a game because of injuries. He played in 15 games, and the one game he missed was the season finale, which he sat out after being suspended by Coach Josh McDaniels.
Sparano said the Dolphins were not aware Marshall would need a medical procedure at the time they made the trade with the Broncos.
Marshall spoke to the media after practice, but didn't mention specifics regarding his injury, deferring all medical questions to Sparano.
On another Marshall matter, on Tuesday he wore 19, which was Ted Ginn Jr.'s old number. Marshall wore 15 during his four seasons in Denver, and it was thought he'd try to get that number from Davone Bess.
But Marshall says the matter is not closed just yet.
"I wouldn't say it's a controversy, but it was an open number when I was a rookie," Marshall said. "I haven't decided on this yet, so it's not in stone. This will be my number for now and we'll have one set in stone before camp."