Rusty joints

A 47 year old white man presented to the outpatient clinic with progressive pain and stiffness of hands and feet of five years duration. During this time he once experienced swelling of the knuckles of his right hand that resolved spontaneously within a week. Diclofenac 50 mg twice daily had not been effective. A year ago ankle osteoarthritis had been diagnosed arthroscopically. He did not smoke or drink alcohol. His father, who had diabetes, also had painful joints. On examination, he was noted to be tanned, with a body mass index of 27. He had subtle arthritis of the second and third metacarpophalangeal joint of the left hand and third metacarpophalangeal joint of the right hand, Heberden’s nodes of several distal interphalangeal hand joints, and crepitus of ankle and knee joints bilaterally. The liver was palpable 3 cm below the right costal margin. Otherwise, physical examination was unremarkable. Laboratory tests and radiographs (fig 1⇓) were ordered.