The midfielder is one of many who are part of Newcastle's walking wounded" this season.
Speaking to reporters before an FA Cup tie at Man City, Howe said: "Sean needs to train regularly to get his best rhythm. I think his training in the last few weeks has been disrupted by an ongoing foot problem he first received against Everton at the end of last season.
"Last week he had an injection but did train, but late in the week. That is always difficult for any player when their training week is disrupted.
"Sean has had some really good games for us this season and he is a really important player. He has game intelligence and his understanding of what we want from him is of the highest level.
"I back him, I back his ability and I know how good he is. He is integral to us when he's at his very best but I do think he needs to train regularly to get his best rhythm."