&Reactive Arthritis=ReA is a syndrome that includes noninfectious inflammatory mono-arthritis occurring after a prior GU or enteric infection and associated with extraarticular manifestations (e.g.  Conjunctivitis, urethritis and various skin lesions such as keratoderma blennorhagica on soles). Acute onset of asymmetric lower extremity oligoarthritis within 2-4 wks of a GU chlamydial infection or infectious diarrhea (such as Salmonella or Shigella) is a common presentation. The joints most commonly affected include mostly knees and less commonly, ankles, and feet. Hip disease is uncommon and and exclusively upper extremity involvment is extremely rare. Low back pain and buttock pain, reflecting sacroiliac inflammation, occurs in 50%25 of cases, but progression to Ankylosing Spondylitis is uncommon. Enthesopathy is a common feature of swelling at insertion of the tendon on bone commonly at the  Achilles tendon.