This has been a great tool for us as it allows me to twist, turn and implement changes of direction on tramps and springy floors, which won’t stress the knee as much as a grass surface would. This is something that will build confidence before you take it out onto the grass.
Once again, if you don’t have access to this you can start to move into small changes of direction, things like S runs which are with slight deviations off line in the shape of the letter S. These basic change of direction drills are important to start with, as the knee, your proprioception and the muscles in your leg will not be used to this and so it’s normal for the knee or your muscles to pull up a little bit sore. Just progress slowly each session and again the less is more approach can be applied as you don’t want to pull up too sore or the knee to blow up and then set you back to just running again.