Wanted: Big Sprocket - for f**ked knee

Gearing down may not help, (well actually that depends what gearing you are using now)

What foot retention do you use?
Do you have one leg longer than the other?
If so is it the calf or thigh that is longer?
How long are your legs?
What size cranks are you using?
Do you have High/low arches?
Does one leg bow in/out during pedaling?

If you do stop cycling (you should for a bit, seriously) does your knee feel better?

Sorry, the doctor said it is probably a cartilage issue. I guess I'll know a bit more once i go for the xray in a few days.

My gear for about a 18 months has been 69inches (46*18). About a month ago i tried out 46*17 - so about 73 inches. I've had some problems with the knee before, in the last 6 months, but changing up a gear recently probably led to the most recent bout of pain.
Took a break from cycling for about 5 days, and swapped back to the old ratio, felt a little better, but riding again certainly made the knee more painful once i was off the bike.

At the moment, I'm using double straps and cages, set fairly loosly - I find that tightening the straps can cause a bit of discomfort in the knee. I've never tried any clipless systems before and have been riding fixed since beginning of 2007, so over 3 years now.

I don't really have answers to leg measurements, I'm 82cm, sit-bone-to-floor and use 165 cranks, but thats it really. To my knowledge my legs are the same length, but i've never had them measured (logic suggests that they can't be the same length anyways).

What would be the best way of finding out specific leg/arch measurements? I could measure myself, but i doubt that would be very scientific.