Doctor Thomas P. Sculco, Surgeon-in-Chief at the Hospital for Special Surgery in New York, explains the ways in which arthritis is commonly diagnosed, including x-rays and MRIs.

It's very obvious from an x-ray if arthritis is evolving. An x-ray is the benchmark, and an x-ray will define very early on if the joint is arthritic or not. And we'll see it very clearly by what we call the narrowing of the articular space, which is where the cartilage is in the joint. And it's very obvious from an x-ray if arthritis is evolving, or if it's another condition. Sometimes if it's more subtle we'll use other imaging studies: an MRI, for example, can be helpful. Or we may use certain blood studies if we're suspicious that it's an arthritis which is affecting the system in general. So there are a number of ways we can identify if the hip is arthritic or not.