"It's too early to tell with any certainty as he had a highly unusual operation and it is difficult to predict how long it will take for the stress fracture to heal," Shuaib Manjra, head of Cricket South Africa's medical committee, told the daily 'The New Age' today.
"The best case scenario is that he returns to playing in around four months, but that could stretch to six months or even longer," he added, raising concerns that Smith may miss not just the tour by India in November but also the Test and ODI series in Abu Dhabi against Pakistan preceding that.
Smith has already been ruled out of the ICC Champions Trophy next month as well as South Africa's ODI tour to Sri Lanka in July. The surgery on Smith's left ankle included two pins being inserted as well as additional bone marrow being injected into six holes to assist the healing process.
"He had a similar operation in 2012 and we thought we had solved the problem only for it to return six months later, so we will have to wait and see how it goes this time," Manjra said.
"This operation will fix the acute problem but we must find out what is causing the stress and balance the load as best we can. Graeme is a big chap and his bones take a lot of stress." Manjra said a special custom-made boot for the foot will be made at the Adidas laboratory in Germany to take the pressure off the ankle.