An inflammatory arthritis can occur in association with inflammatory bowel disease (Crohn’s or UC). It usually affects a large lower extremity joint and often occurs when the bowel disease is flaring. Treatment of the peripheral arthritis is treatment of the bowel. Given your story about the activity of your bowel disease, it seems unlikley that your knee and pelvic problems are related to Crohn’s but you might want to see a rheumatologist.
About Alan Matsumoto, M.D.
Part-time Faculty, Division of Rheumatology
Johns Hopkins University