Key Saints' AFL year over after bad break

St Kilda have suffered a blow with Paddy McCartin departing their clash with Richmond at the MCG with a broken collarbone.

Paddy McCartin's troubled AFL season is over, with the St Kilda spearhead suffering a broken collarbone on Saturday against Richmond.

The 20-year-old received a free kick after he clattered into the legs of Tigers defender Nick Vlastuin in the first quarter at the MCG and left the ground after kicking his second goal.

McCartin was playing in just his 11th game of a season in which he had struggled to shake off persistent concussion symptoms.