Pietersen had to leave England's Test tour of New Zealand before the final match in Auckland, which finished in a dramatic draw and therefore a 0-0 series stalemate.
"Kevin has had a further scan, which confirms a bone injury and bone bruising, and he is being put in a brace for two weeks," England Test coach Andy Flower said.
The mercurial batsman hurt himself in training before the start of the series, in Queenstown last month, and had been complaining of pain in his right leg ever since.
Following scans in New Zealand he flew home last week and, after another check on the injury on Monday, Flower has since given an upbeat update on Pietersen's likely treatment and recovery time.
He added: "He will be off exercise, or any impact exercise, after that for another couple of weeks. Then he'll start his rehab."
When Pietersen left New Zealand, England appeared optimistic he would not need surgery - and so it has proved.
"We anticipate him playing a full part in the summer," added Flower. "He's been in some pain, but we hope he'll be ready to go by the start of the summer."