Hello Kathleen! Please aware that after a hip replacement, the gluteus medius is the primary muscle that needs strengthening, hip bridging, standing terminal knee extension, multi-directional leg raises, and some balance activies. Also be aware that your client should not perform any hip flexion >90*, hip adduction across the midline of the body, and hip internal rotation. Definitely want to stay away from doing a combined movement of these three joint actions.
Best of luck!