Discuss this problem with your mother-in-law and if possible, with her physician. Patients who ask for more medication may seem like they are becoming addicted. It may be that she has just isn't getting adequate pain control.
Lortab is a short-acting pain reliever. It starts working quickly but doesn't last as long as some other drugs. She may need a different dose or a different drug. The doctor who prescribed the drug can help her with this.
Another key factor is activity level. Patients who have had a total knee replacement must be encouraged to keep active and do their exercises. Inactivity causes the muscles to stiffen with loss of motion. Motion is lotion and without it pain levels can increase.