<qa>  What is the current evidence on whether fixed or mobile bearings give the most natural movement or provideThe current evidence on whether fixed or mobile, low or high congruency bearings give the most natural movement or provide better knee function is sparse. By carrying out a randomised controlled trial including a cohort of healthy individuals and taking indepth functional assessments of a number of different common activities of daily living it should be possible to show what level of functional outcome the three bearings being used give. 