Liposuction for the knees and varicose veins?

That procedure by itself that long ago should not prevent you from having liposuction of that area at this point.

Your previous varicose vein treatment does not preclude you from having liposuction on the knees. I have safely performed sclerotherapy and liposuction on the same patient many times. Nevertheless, it’s always important to inform your dermatologic surgeon about prior procedures. You may also want to consider noninvasive fat-elimination techniques, such as Vanquish, CoolSculpting and ThermiTight. Please consult a board-certified dermatologist who is an expert with liposuction and other body-contouring techniques. 

Yes, it should be safe to have liposuction of your knees 10 years after having had varicose vein treatment there. I recommend consulting with a board certified plastic surgeon who discuss your goals, examine you, and can show you before/after pictures so that you can see what type of results you can expect to get. Good luck!