I'd definitely recommend trekking poles, maybe even before some sort of brace. I have bad knees and weak ankles, but I can still do some strenuous hikes because of the poles.

As Be_Prepared mentioned, they take a lot of the stress off the knee while hiking, plus they provide a lot of stability while hiking so you don't twist or tweak anything trying to recover your balance with a heavy pack. Just make sure you learn how to use them properly, it's basically just a stick, but there's still some techniques that make it a lot more efficient, like how to hold them, how to set the right height, etc.