St Kilda's horror year with concussion has continued with Koby Stevens to miss the remainder of 2018 due to ongoing symptoms of the condition, while young forward Paddy McCartin will wear a helmet in his return from his seventh concussion since 2014.

Coach Alan Richardson told reporters on Friday that Stevens would not play again this season, the news coming only a day after Maverick Weller was ruled out of Saturday's clash with Richmond due to concussion suffered at training on Thursday.

St Kilda have also been without Jake Carlisle and McCartin at stages in 2018 due to concussion with the latter missing the past two games.

"He [McCartin] will be a different-looking player in terms of the head attire," Richardson said. "Nathan Burke, a former champion of our footy club [who played in a helmet], has spoken to our doctors and said that whilst the research doesn't suggest much, the player feels a bit more confident [wearing a helmet] .

"He [McCartin] trained with the helmet yesterday. It wasn't a long session, it was a 30-minute session, but he really attacked the footy and played with some real confidence. He'll play with that," Richardson said.