Can I fix knock knees without surgery at age 17?

No. You are done growing at that age so no nonsurgical treatments will change your bone and me alignment. The bigger question is are you having problems with it? There is a variation of normal among people in unless you're having problems I would not worry about it. If you are having difficulty you should seek an orthopedic surgeon and a major surgery would be required to realign your legs. This is usually not necessary.