This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Orthopaedics
[{'content': 'Syndesmophytes are seen in - \nSelect and explain. \nA. AS, B. RA, C. OA, D. All', 'role': 'user'}, {'content': "Answer: A \nExplanation: Syndesmophytes \n\nSyndesmophytes are thin, slender vertical radiodense spicules bridging the vertebral bodies, giving the spine `bamboo' appearance. They are actually ossification of outer fibres of annulus fibrosus.\n\nSyndesmophytes are seen in :\n\nAnkylosing spondylitis\nPsoriatic arthritis\nReiter's disease\nArthritis associated with Inflammatory bowel disease", 'role': 'assistant'}]