In the simplest possible words, there is nothing holding the hip ball in the socket except muscle. To do the procedure they have to open up a slot between muscles. You can have the traditional lateral approach where the opening is from the side (and thus crossing your legs or twisting can cause the hip to dislocate, but other movements are relatively safe), or you can have the frontal approach (where the opening in the muscle mass is on the anterior side of the leg, with good structural support laterally/posteriorly and only minimal risk of the ball slipping toward the front of the muscle mass. Most athletes and folks desiring the best range of motion after surgery are likely to be given the anterior approach. Thats what you had and you can be expected to do fine with a modicum of recovery time. My wife at 77 years old has great range of motion, rides a bike, hikes, and by in large keeps up with me even with a double hip replacement that has been in place for serveral years.