<prompt> A 65-yr-old man with HO back pain since 3 months. ESR is raised. On examination marked stiffness and mild restriction of chest movements is found. On x-ray, syndesmophytes are present in vertebrae. Diagnosis is -Ankylosing spondylitisDegenerative osteoarthritis of spineAnkylosing hyperosteosisLumbar canal stenosis  <response>: The clinical profile of the given case fits into Ankylosing spondylitis A.S. except for the age.A.S. is usually seen in 2nd or 3rd decades of age with a median age of 23. However in 5 ofpatients, symptoms begin after 40 - HarrisonAll other features, i.e. raised ESR, marked stiffness, restriction of chest movements syndesmophytes are seen in A.S. 