No further testing is necessary for this patient who clinically appears to have hand osteoarthritis. Osteoarthritis is a clinical diagnosis, and the cardinal symptom is pain with activity that is relieved with rest. Affected patients also typically experience morning stiffness that lasts for less than 30 minutes daily. Bony hypertrophy is commonly detected in the fingers, and Heberden and Bouchard nodes may be easily palpated. Osteoarthritis also may cause squaring or boxing of the carpometacarpal joint at the base of the thumb.

This patient has no clinical signs or symptoms suggestive of a systemic inflammatory disease and therefore does not require diagnostic testing with antinuclear antibodies (ANA) or anti–double-stranded DNA antibodies. A positive ANA test result has low predictive value when the pretest probability of systemic lupus erythematosus or a related disease is low. Therefore, this test should not be used to screen indiscriminately for the presence of rheumatologic disease. The American College of Rheumatology recommends not testing ANA subserologies such as anti–double-stranded DNA without the combination of a positive ANA and elevated clinical suspicion of autoimmune disease, which is not present in this patient.

Radiography is not needed to confirm the diagnosis of osteoarthritis in patients with a history and physical examination compatible with this condition. Clinical examination is more sensitive and specific for the diagnosis of hand osteoarthritis compared with radiography.

The key features of rheumatoid arthritis (RA) are swelling and tenderness in and around the joints. Prominent morning stiffness that usually lasts more than 1 hour characterizes early RA. Rheumatoid factor positivity is characteristic of RA, although rheumatoid factor has a low specificity for diagnosis of RA. Rheumatoid factor may be present in healthy persons, especially at older ages. Because this patient has no clinical evidence of RA, testing for rheumatoid factor is unnecessary.