In reply to John Ww:
CTi braces seem to be gold standard for motocross and skiing. If the off the shelf ones fit, less spendy than full custom ones (still spendy mind you).
Don Joy is another company, that is rather popular with sporty post knee-op persons (and a tad cheaper than CTi). Don Joy also offers fully custom/fitted braces.
I ended up with a second hand Don Joy Defiance (or something like that) about 10 years ago, after my ACL+meniscus repair surgery. Sure a fully customized one would have been a perfect fit, I still got like 9/10 fit from the stock model. So, as I said, a fully custom one might not be needed...