The WRU are hopeful the Kiwi can be fit in time to take charge of the tour Down Under, with backs coach Rob Howley primed and ready to take over if he doesn't make it.
And Gatland's wife Trudy revealed the injury came about as the Wales boss was preparing his holiday home for the visit of a journalist.
"Warren will see closer to the time whether he can get to Australia or not," she said.
"A woman had wanted to feature our bach [New Zealand word for beachside holiday home] in a magazine and was coming that morning so we were getting things ready and Warren was doing the windows for me, which was very kind.
"I think we'll get the professional back in future. We should have done that in the first place, but it could have been much worse.
"Luckily he landed on his feet because he could have landed on his head.
"He landed falling backwards, so his heels took the impact and the calcaneus bone, that heel bone, is a really painful injury.
"He's being very brave but it is very painful.
"He's hopeful it won't be too long that he's off his feet but he is going to be in two casts initially.
"His left foot hopefully will mend quite quickly because it's just got one fracture on the heel, but the other one that needs the surgery has a lot more shattered pieces.
"The [Wales] coaches are just going to step up and do the job of getting the boys prepared for Australia, and then Warren will see closer to the time whether he can get to Australia or not."