Lüdemann played some junior hockey in Canada, for three seasons in the Alberta Junior Hockey League with the Fort McMurray Oil Barons, before returning to his native Germany, signing with the Kölner EC. In 1995, Lüdemann would win with Köln the German championship after defeating EV Landshut. He would then rise and establish himself as one of the best defencemen of the DEL, playing a reliable game and showing some excellent offensive abilities. He would become German champion a second time in 2002 after a win over the Adler Mannheim.