Effusions and osteoarthritis

We can see here 3 signs in the articular surface and other three one in joint space.

1-The three signs seen in the joint space are:

-Narrowing specially supero-lateral margin.

-Vacuum phenomena.

-Calcification.

-Effusion ( seen by MRI ).

2-Three signs shown in articular surface which are:

-Subarticular sclerosis.

-Subarticular pseudocysts.

-Osteophytes.

2-D.D.between avascular necrosis and osteoarthritis:

-No acetabular changes in avascular necrosis.

-Superior aspect of joint space is preserved in avascular necrosis.

-No fissures, but pseudo cysts in case of osteoarthritis.