Fig. 4. Pelvic radiograph of 33-year-old man with ankylosing spondylitis. A. Pincer type femoroacetabular impingement pattern showing lateral center-edge angle estimated to be 52.3°. B. Demonstrating bilateral sacroiliitis grade 3, showing subchondral sclerosis and irregularities of the joint surface, including erosions. Fig. 4. Pelvic radiograph of 33-year-old man with ankylosing spondylitis. A. Pincer type femoroacetabular impingement pattern showing lateral center-edge angle estimated to be 52.3°. B. Demonstrating bilateral sacroiliitis grade 3, showing subchondral sclerosis and irregularities of the joint surface, including . . . J Korean Soc Radiol. 2015 Jun;72(6):385-392. http://dx.doi.org/10.3348/jksr.2015.72.6.385