Legal Question in Personal Injury in Massachusetts

I am assuming that this is a personal injury case, such as an auto accident. Generally, victims of negligence are entitled to recoup their lost wages along with pain and suffering, medical bills, etc. That settlement amount, or jury award, is paid as a lump sum including all of the losses the victim suffered. I have never heard of an attorney taking a percentage of just the lost wages, or doing so before the case is even settled. Without further information, it does not sound appropriate to me. There may be some other prearranged agreement of which I am not aware.