A 65 year old lady presents with worsening pain in both knees for 3 years. She is unable to walk for more than half an hour at a stretch because of the pain, which is exacerbated by kneeling, squatting, or descending the stairs. Both knees are stiff for around 20 minutes after waking up; the stiffness as well as the pain are relieved by resting. There is no history of pain, stiffness or restriction of hand movements. Her medical and drug histories are unremarkable.
ESR: 11 mm/1h (< 15) CRP: 0.5 ng/l (< 6)
The X-rays of the knees appear normal.
The MRI scan reveals degeneration of the articular cartilage, in combination with subchondral bone changes and marginal osteophyte formation (<5mm in size), in both joints.
Rheumatoid Factor: negative