A 50-year-old man presents to the clinic complaining of fatigue and painful swelling of both hands. He also describes being very "stiff' in the morning and requires much longer time to get ready for work. On physical examination, there is erythema, swelling, and tenderness on palpation of the proximal interphalangeal joints and MCP joints. The pattern of joint swelling is symmetric. Plain x-rays of the hand are ordered. Which of the following x-ray findings is characteristic of this condition?