Speaking in Christchurch today, Dr Robinson said: "It was always on the cards. But we wanted to wait and see what was happening.
"Richie had a scan earlier in the week and saw a specialist yesterday to discuss the best options for him. While the initial stress fracture in his foot has partially healed, the scan revealed that there is an area of bone stress around the screw.
"The best option for him is to have surgery to have the screw removed, he will also have some bone grafting done and then his foot will be left alone to heal.''
She said McCaw was fully fit entering the Rugby World Cup but injured his foot during the pool match against France and he wasn't able to train between games. It was often quite swollen and painful and many had remarked it was incredible he was still able to play on it.
"It was really good until the France pool match and that's when he was very sore,'' Robinson said. ``We knew he was sore. But we knew he was safe to carry on and wasn't doing any damage that he couldn't recover from later on.
"The big screw in there helped him get through to the final.
"He said he didn't want people to think he was being incredibly brave running around out there - he had pain, but he was ready to go each week.
"It would swell up in a game but would be better through the week. He recovered, but admittedly, he couldn't train.
"On game day we would give him some pain relief and anti-inflammatory.''
The metatarsal bone has laid low several top international sportsmen including English footballers David Beckham and Wayne Rooney.
Dr Robinson described McCaw as "a notoriously bad healer'' but, given time to recover, should return to full fitness early next year.
Talking about his future in the game after surgery, she said: "If we get it healed properly, he'll be good. We have to take the time, and we've got that now. This was a big year, but now we're good.
"We'll probably give him a reasonable period of training before coming back to games, because we've learnt that games are a lot different from just training.
Dr Robinson would not put a time-frame on his return to competitive rugby, saying: "It's a long time away and to put a date on it is silly _ you can only get it wrong.
"But most fractures take six weeks to heal. Following the surgery, Richie will be in plaster for two weeks and then a moonboot for a month. After around 10 to 12 weeks he will be able to start running and then will gradually return to rugby training.
"The most frustrating thing for him is being in a moon boot, which limits him so much.''
