@elpasomanualpt: Why do some people develop hip arthritis in only one hip when both hips are the same age? Dr. David compares your hip joints to the tires on your car. When your tires are out of alignment, they can wear unevenly. He uses this example to explain how muscle imbalances and uneven pressure through your hip joints may affect the way your hips move and function. Age isn't the only factor involved in hip osteoarthritis. Muscle strength, joint mechanics, and how you move can also play a role in your hip health.