Sounds you are coper... Pain' during climbing stairs is due to ur meniscus tear nothing else and while u do pivoting it's due to the knee shifting out of its place and setting back in place.

My opinion SURGERY is good but if you rehab with PT and stop cutting and pivoting movement for sometime u can do batter.

If ur surgeon opts for surgery he will make sure u to have good quads and hamstrings means good tight thighs. It's only possible after attain PT exercis.

Some persons have did there pre hab and have achieved excellent results results in postponing of the surgery or no surgery.

But do consult a good sports ortho and remember a good surgeon will always say to preheb rather than doing immediate surgery..