The German international felt increasing pain in a dead leg he suffered against Charlton on Boxing Day and after telephoning the club doctor that night, was rushed to hospital for emergency surgery.
Christian's right thigh had swelled to double its normal size - known as decompartmentalisation of the muscle - and led to complications with his blood supply.
Thankfully, the operation was a success and he will undergo further surgery to have a 10-inch wound closed.
A naturally concerned Glenn took up the story after Sunday's 2-1 defeat against Newcastle at St James Park.
He said: "Christian had an emergency operation on Boxing Day evening after what was a dead leg. We didn't worry about it after the game.
"There is a medical term for it - decompartmentalisation of the muscle is the problem - and it grew to double the size and he had to have this emergency operation.
"First and foremost was to get Christian in and dealt with because there were complications with the blood supply, and that can be very dangerous.
"That was always our first concern and fortunately through Christian phoning our doctor and getting hold of it very quickly, it saved any sort of, well, I wouldn't like to go to the next part.
"But he's okay, he's had an operation and he'll be dealt with tomorrow when he's having the second part of the leg seen to.
"Basically, the muscle has grown to double the size and the pressure on it stops the supply of blood and it had to be released.
"He's got a 10-inch scar now. He's had to have it slit and released, but it's had to be kept open until the muscle goes down. It's one of those that can only be closed up when the time is right.
"It's a big blow football-wise, but I'm not concerned about that.
First and foremost, it's his health that's more important. That will always come first in front of football.
"I would think it would be very difficult for him to return before the end of the season but the major thing is that he's okay."
Glenn Hoddle has revealed the full extent of the horror injury he expects to end Christian Ziege's season.