Kerr is set to miss Sunday's AFL clash with the Western Bulldogs at Etihad Stadium after his left knee swelled up following a WAFL hit-out last Saturday.
The 30-year-old, who underwent surgery on his right knee in December, has struggled to regain peak fitness this year due to a limited pre-season and ongoing knee issues.
If his latest complaint doesn't settle down over coming weeks, Kerr might need another round of surgery that would prematurely end his season.
Kerr's contract runs until the end of next year, and Worsfold is adamant the 220-game veteran remains a required player at the club.
"He is never going to have perfect knees," Worsfold said.
"But if we can get him to a point where he can train at the required level and therefore play at the required level, then he has a lot of good games ahead of him.
"With Daniel, we know that even at 80 per cent fitness, he can still perform really well, but that is getting tougher and tougher with the issues that he has been carrying.
"Really it is around whether we can we get his body right. I am sure he's got brilliant football left in him if he is as sound as he can be."
Ruckman Nic Naitanui could also be set for an early finish to the year due to ongoing groin soreness.
Naitanui is expected to be replaced by Scott Lycett for Sunday's game against the Bulldogs.
Midfielder Scott Selwood is in line to return from a fractured thumb, but Luke Shuey will miss three games with a hamstring injury.
The Eagles sit two games adrift of eighth spot, and are only a slight chance to make the finals.
