A 74-year-old female complains of difficulty in opening
screw top bottles. She also complains of pain in her knees and hips. There are
no systemic symptoms.
On examination of her hands she is noted to have squaring
of her carpus bilaterally.
Hb 12.5 g/dL
ESR 28 mm in 1st hour
Rheumatoid factor 40 IU/L
This patient is most likely to have: