Why does ankylosing spondylitis cause joint stiffness?

Ankylosing spondylitis can inflame the joints between the spine and pelvis, small spinal joints, and places where tendons attach to bone. Pain and inflammation encourage muscles to tighten, so the back, hips, shoulders, or other joints may feel restricted. Over time, repeated inflammation can lead to structural changes that further limit flexibility. Joint stiffness is often more noticeable after rest, while symptoms and affected areas vary between people.

Regular low-impact movement can keep joints moving through a comfortable range. A physiotherapist can tailor posture work, spinal mobility exercises, breathing exercises, and strengthening to your abilities. Warmth may loosen muscles before activity, while pacing helps avoid a flare after doing too much. Take prescribed medicines as directed and record which activities, rest periods, or treatments change your stiffness so your clinician can refine the plan.

Contact your clinician if stiffness is worsening, interferes with sleep or daily tasks, or comes with new weakness, numbness, bladder or bowel changes, fever, or unexplained weight loss. Sudden severe pain after an injury needs urgent assessment, particularly when the spine is affected.

Ask which joints are involved, how to exercise during a flare, whether your treatment needs review, and which symptoms should prompt urgent contact.