A 69-yeаr-оld wоmаn presents with grаdually wоrsening stiffness and aching in her hands that is most noticeable after gardening. She reports that the discomfort improves after a few minutes of movement. On examination, you note firm, bony enlargements of the distal interphalangeal (DIP) joints bilaterally without warmth or erythema. The NP knows that these findings are most consistent with which of the following?