It seems to me that if a saddle is set on the verge of being too high, then a small incease in heigth, even as little as 1/8" may well cause a problem in an already troublesome knee. Carbonfiber Boy has posted numerous times an accepted method, one I use myself successfully. Sit normally in your saddle and place the heel of the shoe on the peddle with the leg straight but not locked out. This illiminates considerations of cleats, and sole thickness. From there, you can go up or down a mm or two based on riding experience. I have a troublesome right knee myself and my solution is to strengthen the muscles and ligaments that surround the knee with knee specific exercises. Almost all of our movement is forward with almost not to the sides.

The link shows some knee exercises. https://www.webmd.com/pain-managemen...ysical-therapy For myself, I focus on exercises that emphasize lateral moves such as a tennis player shuffling from left to right or a basketball defensive player shuffling sideways while guarding someone on offense. I do these at least once a week or more during flarer-ups. I'm 81 y.o. and so far my knees are doing well. If I don't do the exercises discomfort persists.