My sister has a stress fracture in tibia. what's the likely treatment going to be?

Rest: Stress fractures occur when the stress of her activity level has gone beyond the ability of the bone to heal and repair itself. Treatment is usually rest, and is in part based in the degree if activity that led to it. For example, a runner may just have to stop for awhile; a sedentary person may need a cast and crutches. Discuss your specific case with your doctor.