Carswell was brought into the fold at wide receiver to bring competition to the group that is dealing with injuries at the top of the depth chart.
His injury came just a day before the team brought in former Colt Austin Collie for a workout. And while Jim Harbaugh said it went well, it remains to be seen whether or not he has a future with the 49ers.
"He had a patella tear seven-and-a-half months ago and he's pretty far along. Pretty impressive," Harbaugh said.
But when asked how his knee effects his chances of signing with San Francisco, Harbaugh said that's up for the doctors to decide.
Carswell spent last season on the practice squad for the Raiders.