I had liposarcoma surgery on my left leg ten months ago, why am I still having pain?

Check with your doc. Depending on the amount of tissue removed, postoperartive pain syndromes are not uncommon, especially if it was a large tumor and you received radiation. Your surgeon is the best person to discuss this with. Sometimes referral to a pain specialist is warranted if the pain is severe.
It depends. Persistent pain after major surgery is not unusual. It can be from adhesions and scar or a neuroma at the operative site. Infection or fracture of the adjacent bone can also occur. The best person to ask is the surgeon who did the original resection.