Question

which joint(s) involvement is considered to the hallmark of ankylosing spondylitis? knees lumbar spine sacroliliac joint cervical spine

Explanation:

Ankylosing spondylitis is a chronic inflammatory disease, and sacroiliitis (inflammation of the sacroiliac joints) is a characteristic and early - presenting feature, often considered the hallmark of the disease.

Answer:

sacroliliac joint