The injury leaves question marks over Griffiths's playing future, but the 35-year-old hopes the news doesn't signal the end.
"It has been one of the worst years of my life, football-wise," Griffiths said.
"I hope I don't have to go out like this and if I have anything to do with it I won't.
"A lot of people have written me off in the past and I have proved them wrong.
"In the back of my mind this time they may be right but I will be doing everything possible to get back.
"I am a very determined person and when I want something I usually get it – just ask my wife!"
The striker will undergo an operation in the next four to six weeks once the swelling is reduced.
"I have absolutely loved it at the Phoenix where the culture is fantastic," Griffiths, who joined the club from Newcastle Jets, said.
"I was so down after the problems at Newcastle and what I found in Wellington was a breath of fresh air.
"I take my hat off to Ernie (Merrick) and Dura (Andrew Durante) for making the opportunity available.
"Those two put so much faith in me I am more upset at not being able to contribute for the rest of the season."
Griffiths also revealed that he had been offered a contract by the Phoenix for next season.
"The club put an offer in front of me and after discussing it with my wife I was going to sign another contract," he said.
"It (the club) is very special and I believe it has a great future."
Phoenix coach Merrick said he believed Griffiths had handled himself well after the devastating injury news.
"He was a great acquisition for our squad and it is a major blow for him," Merrick said.
"I have to say he is coping very well with what has happened and that is because he is an extremely positive person who fitted easily into our culture.
"Joel has always been fit and professional in the way he has looked after himself and I strongly believe he will come back from this and play in the A-League again."
Griffiths picked up the injury in last Sunday's 3-0 loss to Melbourne Victory in Wellington.
