Psoriatic Arthritis and the SI Joint

The sacroiliac joints connect the base of the spine with the pelvis. Inflammation there may cause pain deep in one or both buttocks, the lower back, or the back of the thighs. Stiffness can be worse after rest and may ease somewhat with gentle movement, although prolonged activity can still aggravate symptoms.

Pain in this area can also come from muscles, discs, hips, or other structures. A clinician may ask about night symptoms, morning stiffness, alternating buttock pain, skin psoriasis, and other joint symptoms, then examine your spine, hips, and pelvis. Imaging may be considered when the pattern needs clarification.

Change position regularly rather than sitting or standing for a long stretch. Try gentle walking and mobility exercises within comfort, and ask a physiotherapist to show you movements that support the hips, pelvis, and trunk without provoking a flare. A supportive sleep position, such as side-lying with a pillow between the knees, may reduce strain for some people.

Use prescribed treatment consistently and discuss persistent symptoms with the clinician managing your psoriatic arthritis. Anti-inflammatory medication may be considered for suitable patients, but medical advice is needed because health conditions and other medicines affect its safety.

Arrange an assessment for ongoing deep buttock or back pain, stiffness that returns after rest, or symptoms that interfere with walking, sleep, or work. Seek urgent care for new leg weakness, numbness around the groin, loss of bladder or bowel control, fever with severe back pain, or pain after a significant injury.

Ask whether your symptom pattern suggests sacroiliac inflammation, whether imaging is useful, which exercises are safe, and how to recognise a flare that needs treatment review.