Hip dysplasia is seen when the bones of your hip joint fail to align properly. Even though it mainly impacts babies and young children, it can be seen in adults too. 

The hip joint serves as the gathering point between your thigh bone (femur) and your hip bone (pelvis). If one is having hip dysplasia then the femur's round ball (femoral head) doesn't correctly match up with the curved socket in your pelvis that it should fit into.