one thought is a shorter crank arm will mean shorter range of motion, which will either help in the long term, or put your knee under more strain short term.
I think it pretty much depends upon what the problem is.
I have floppy ligaments and find I get on better with longer cranks, though 175’s are OK and I’ve got used to them switching to 170’s can cause pain, but it depends on what I do with the saddle to compensate for the lack of 5mm at the bottom of the downstroke. (either move it back or raise it, or a bit of both)
180’s were nice, but felt kinda gangly pedalling bigger circles…that was on a SS though so high cadence.