Dale Steyn aggravated the injury during day two of the first Test against Australia in Perth on Friday.
The 33-year-old paceman said it was a similar injury to the one he suffered against England late last year, but likely worse.
“I did something very similar against England in December in a similar area, but it wasn’t as bad,” he told Channel Nine.
“That was a stress reaction which is like a very hairline, small little crack, but this time it’s more of a fracture so it’s kind of broken the whole bone.
“I’ll probably look to have surgery and have to put a plate in there and get the bone kind of back together or something like that.
“We’re probably looking at a minimum of six months before I’m going up again.”
The injury is a huge blow to Steyn and South Africa, who recovered to take control of the first Test.