A 35 year old woman presents with intermittent back pain and stiffness for 10 years, which have progressed over time and are now debilitating, preventing her from conducting her daily household activities. These symptoms are worst in the morning; they initially resolved over a few hours, but have become persistent now. Due to financial reasons, she has never sought medical advice, preferring to medicate herself with over-the-counter analgesics. Her medical history is otherwise unremarkable. There is no history of trauma.
The rheumatoid factor assay is negative.
ESR: 38 mm/1h (<20) CRP: 4 mg/dL (0-1.0 mg/dL)
There is grade 2 sacroiliitis of both joints.
There is squaring of the vertebrae, syndesmophyte formation and ossification of the spinal ligaments (i.e. a bamboo spine).