He had hoped to feature in the Gills final couple of games after returning to training in February.
But Stimson told BBC Radio Kent: "He won't play this season. It's unfortunate. I'd be amazed if he does."
"He's still doing a little work with the physio but it's a slow process and we've just got to keep his spirits up as much as we can.
"So if any supporters see him around the place then just give him a pat on the shoulder and tell him to keep his chin up. He's one of these guys who loves playing football and at the moment it's really frustrating for him."
Source: BBC Sport
Source: BBC Sport