The practical use is little more than to simply turn your knee away from the bench, then turning back. The turns are always toward the outside of your workout area.

If this step bothers your knees, or you are concerned that it might bother them, simply modify the step to a backwards-forwards move rather than the twist. Just remember that for the modification to work properly, you will need to use knee lifts as part of it. Knee lift on the bench before walking backwards, then another knee lift before returning to your step bench.