Adapting the modulation, power and channel code to the current channel state for OFDM systems is an important topic for future wireless data transmission to fully utilize the given channel conditions. The consideration of practical channel codes in Link Adaptation schemes is still under investigation, especially if imperfect knowledge of the channel conditions is assumed. In this paper, the ramifications of imperfect channel knowledge on capacity based Link Adaptation will be discussed and a solution will be proposed. In particular, robustly adapting the LTE turbo code employed in this paper was found to be extremely important for the overall performance of the system.