If your doctor does your surgery from the back part of the hip, called a posterior approach, you need to avoid bending your hip more than 90 degrees. You can kneel down, but try to avoid kneeling directly onto the operated side. If you must kneel, keep your weight even on each side. While kneeling, avoid bending too far forward at the hip because you could bend your hip past the safe limit of 90 degrees.
Do not get onto your hands and knees. This position immediately puts your hip at a 90-degree angle, and the added pressure of your body weight on your hip could force the hip to dislocate out of the socket.