I have knee and (to a lessor extent) hip problems, but I don't want it to force me to stop skating - especially since I want to start synchro again. Does anyone know of a good knee brace that I can ask my orthopedic for?

Rather than asking your ortho for a specific brace, you should be asking your ortho what's wrong with your knee, whether skating is advisable, and what you need to do to be able to skate. You could wind up doing long term damage to your joints that is irreparable. And some knee problems are made WORSE by bracing.

This is the voice of hard-learned experience: related hip, lower back, and knee problems. I ignored them, then tried to skate through them, then wound up being so messed up I was off the ice for almost 6 months. It took 3 YEARS to get things put back together and healthy. (And I still have knee problems, as many folks here will attest.)

If you haven't gotten a diagnosis from a good ortho and/or PT, please do it before you try to self-treat and skate!!