It can also cause swelling, limited motion in these areas, and in some cases, fusing of the spine.
[stanfordhealthcare.org]
For example, an adult may have iritis, heel pain (enthesitis), and knee swelling, WITHOUT back pain, psoriasis, a recent infection, or intestinal symptoms.
[spondylitis.org]
It can cause pain and stiffness in the low back, middle back, buttocks, and neck, and sometimes in other areas like the hips, chest wall, or heels.
[stanfordhealthcare.org]