Which procedure would be most beneficial for facial plastic surgery to remove deep labial folds and how often would I need the procedure done?

My question is about hair transplants for eyebrows, but I'm not sure if this falls in the plastic surgery category. I have very little hair on my brows (I'm not sure if it is from medicines or aging). I want to know if it's possible to have hair replacement surgery done in this area? If not, are there other procedures to encourage hair growth in the eyebrows?