Born and raised in South Africa, Koen played his youth rugby for the Falcons in his home province. However, a lack of domestic opportunities saw him move to New Zealand in 2004.[5] He has played club rugby for the Invercargill based Pirates Old-Boys since arriving in New Zealand and eventually made the Southland ITM Cup side in 2012 where he made one appearance. He fully established himself as a starter during the 2013 ITM Cup campaign and an injury crisis in the Highlanders front-row towards the tail end of the 2014 Super Rugby season saw him earn a first Super Rugby cap in a 44-16 defeat by the Waratahs on 6 July 2014.[6]