Ankylosing spondylitis typically starts at the sacroiliac joints in males; in women it usually begins in which joints?

• A. Sacroiliac joints
• B. Peripheral joints
• C. Spinal joints
• D. Costovertebral joints

Answer: (B)

In ankylosing spondylitis, the initial pattern of joint involvement differs by sex. Men commonly start with inflammation in the sacroiliac joints, part of the axial skeleton. Women, on the other hand, more often begin with peripheral joint inflammation, such as in the knees or ankles, before axial features become prominent. Although spine and costovertebral joints can be involved later in either sex, the typical starting site in women is the peripheral joints.