Two thoughts. First, if you are cutting your Miscanthus low to the ground in spring you are promoting "sprawl." Leaving 8-10" of old stems helps to support the current growth more vertically. Having said that, the natural form is a spreading vase shape. You can contain that somewhat by forcing the plant up with a green plastic stretch-tie looped around the plant several times, then pulled tight.
hortster

Thank you. The pruning technique sounds like excellent advice.

For now I removed some of the outer stems to make it a little smaller. Next year I will cut it back higher.