He is just one example of the 76 per cent of players that AFL Players' Association research revealed as leaving the game with a serious injury.
Of those, 64 per cent require ongoing treatment.
In recognition of these figures, the AFLPA will on Tuesday re-launch their injury and hardship fund after allocating $24.7 million to the fund in the latest collective bargaining agreement.
The fund contains five elements relevant to former AFL players, such as lifetime health care that enables players to access up to $8000 to cover treatment costs for joint injuries and dental procedures related to football.
There are also funds available if a player suffers a football career-ending injury or battles to work immediately after being removed from an AFL list due to injury, as well as past player hardship grants and hospital excess reimbursement.
The criteria around football-ending injuries has been broadened to better capture the growing number of players giving up the game due to the effect of concussion.
Knights said he hoped the availability of such money would provide many people with peace of mind as they attempt to transition to a life away from the game despite wearing many battle scars.
"It's a tough game but you have got the comfort and support when you finish that we're actually going to look after you [and] we're not getting to forget you," Knights said.
Knights said he is lucky he was able to start a company, ZibMedia.com.au, that didn't rely on physical labour but football injuries impact many players when they re-enter the world outside the AFL.
Even those that stay working in the game can struggle to stay as active as they would like because of the injuries suffered when playing, with Knights saying how tough it is for his former teammate Nathan Foley to not be able to run because of an injury he suffered in his career.
Knights, who emphasises being an AFL player was brilliant, hopes he has had his final football related operation but he can never be sure.
That's why he is rapt both the AFL and the players' association have not neglected past players.
"Keeping active is good for your mind too, which is why it is really important," Knights said.
"As a 30-year-old you should still have many active years ahead of you."
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Peter Ryan joined The Age in 2017 having covered AFL as a senior reporter with AFL Media.
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