Acetabular osteitis in ankylosing spondylitis: Does fibrillin figure in its pathogenesis?

In the hip and sacroiliac joints, ankylosing spondylitis attacks the acetabulum over the femoral head and the ilium in preference to the sacrum. Both sites involve inflammation in bone subjacent to fibrocartilage with relative sparing of opposing, hyaline cartilage-surfaced mates. This disease appears to target connective tissues rich in fibrillin-1. A cell-mediated autoimmune response may be involved.