<prompt> In a middle aged male having back pain, syndesmophytes involving 4 continous veebrae are seen on Xray. The patient has ?DISHAnkylosing spondylitisRheumatoid ahritisOsteoahritis  <response>: Ans. is b i.e., Ankylosing spondylitis Back pain with syndesmatophytes in a middle aged man suggest the diagnosis of ankylosing spondylitis. 