A 37-year-old male presents with a history of pain and
swelling of his knees. He also has a low backache.. He also complains of pain
and redness of his eyes and he has a discharge per urethra. 2 weeks prior to
the onset of the illness he had diarrhoea for several days. This was
He is not on any medications, smoke 5 cigarettes a day
and takes 12 units of alcohol per week. He is married has 2 children and is an
On examination of his knees there are bilateral effusions
and limitation of movement. Aspiration of the joint shows that the effusion is
sterile. X-ray of his pelvis shows sacroiliitis.
What is the likely diagnosis?