A 62-year-old woman presents to the clinic with chronic joint pain in her hands, worse at the end of the day and after prolonged activity. She describes stiffness in the morning lasting less than 30 minutes. Physical examination reveals bony enlargements and tenderness at the distal interphalangeal (DIP) and proximal interphalangeal (PIP) joints, but her wrists and metacarpophalangeal (MCP) joints are unaffected. X-rays show joint space narrowing, subchondral sclerosis, and osteophytes in the affected joints. Which of the following is the most likely diagnosis?
