Inflammation of the GI tract may increase permeability, resulting in absorption of arthrogenic antigenic material These antigens may localize in musculoskeletal tissues causing an inflammatory response.

50% HLA-B27 and associated with IBD, Gastric Bypass Surgery, Coeliac and 

Whipple’s disease. It is more common in Crohn’s Disease.

Asymmetrical joint involvement, erythema nodosum, uveitis, enthesitis. 

Abdominal pain, weight loss, diarrhoea, ulcers, skin changes, joint pain, loss of 

Bloods: FBC, ESR, CRP, HLA-B27

Imaging: X-ray shows non-erosive sacroiliitis

Worse long term prognosis if axial involvement 

Chronic arthritis, secondary amyloidosis