Wellington teenager Max Hurd had his neck and back brace off for just 24 hours before receiving an urgent phone call from his surgeon telling him to put it back on immediately.
On Thursday, the 17-year-old -- who tumbled 100m down a cliff on December 5 while out walking with relatives in the Wairarapa -- was given the all-clear from doctors to remove the brace he had been wearing for the previous six weeks.
He considered this a "milestone" in his recovery.
But a call to Max's mother from his surgeon yesterday afternoon put a sudden end to his feeling of freedom.
"The surgeon phoned me and said that they had had another look at his x-ray and he wasn't happy about it," Svea Cunliffe-Steel said. "It looks like the front of the vertebra in his neck has collapsed.
"He said it could just be the angle of the x-ray ... but he said the worst-case scenario is that they will have to operate on Max's neck because it has not healed the way it should.
"In the meantime, Max has got to wear his brace 24 hours a day, for obvious reasons."
Last month, Max fell during a run up a hill while out walking with his cousins and uncle on the Deliverance Cove track.
It was the day after his birthday and the day before he was due to start equestrian school.
As he reached the top, he fell, possibly as the result of a seizure or from passing out through over-exertion. Whatever the reason, he plunged down the side of the hill.
Max was rushed to Wellington Hospital in a critical condition. He had a broken neck, five fractures in his back, extensive bruising and brain damage. Remarkably, his spinal cord was not torn.
Now, six weeks on from the accident and after being initially allowed to remove his brace while at home, Max will have to head back to hospital for a CT scan and may face more surgery.
Ms Cunliffe-Steel said her son would have to wait until Thursday afternoon for the results of the scan.
"If he does have to have his neck operated on, well that is a whole other ball game. That is back into hospital, back into rehabilitation, neck brace... I just hope it doesn't have to go that far," she said.
"I'm worried. There are always risks with [surgery]. The artery that caused his speech problems is right there and there are a lot of important blood vessels and nerves there.
"The doctors know what they are doing but there are always risks associated with that and it just delays his recovery time."
Ms Cunliffe-Steel said her son had taken the latest news "in his stride" but was frustrated that he would have to continue wearing the brace.
"He is disappointed because he was really hoping to get the brace off, and now he will have to keep wearing it."