Arthritis — Imaging Features

A 52-year-old woman from Delhi presents with a 6-month history of progressive pain and stiffness in both hands, wrists, and knees. She reports morning stiffness lasting 2 hours. On examination, she has symmetrical swelling of the PIP and MCP joints bilaterally. Laboratory investigations show: ESR 68 mm/hr, CRP 12 mg/dL, and RF 320 IU/mL (positive). Plain radiographs of the hands show periarticular soft tissue swelling, juxta-articular osteopenia, and early marginal erosions at the MCP joints. What is the most characteristic radiological finding in this patient's condition?

A 52-year-old woman from Delhi presents with a 6-month history of progressive pain and stiffness in both hands, wrists, and knees. She reports morning stiffness lasting 2 hours. On examination, she has symmetric swelling of the proximal interphalangeal and metacarpophalangeal joints bilaterally. Laboratory investigations show ESR 68 mm/hr, CRP 12 mg/dL, and RF 120 IU/mL. Plain radiographs of the hands show periarticular soft tissue swelling, periarticular osteopenia, and marginal erosions at the MCP joints. What is the most characteristic radiographic finding in this stage of her disease?

A 68-year-old man from Mumbai presents with a 10-year history of progressive pain in both knees and hips, worse with activity and relieved by rest. He denies morning stiffness. On examination, he has bony enlargement of the DIP joints (Heberden's nodes) and reduced range of motion in both knees. Laboratory tests show normal ESR, normal CRP, and negative RF. Plain radiographs of the knees show joint space narrowing predominantly in the medial compartment, osteophyte formation at the joint margins, and subchondral sclerosis. What is the most characteristic radiographic finding that distinguishes this condition from rheumatoid arthritis?

A 58-year-old man from Mumbai with a 10-year history of osteoarthritis of both knees presents with progressive pain and functional limitation. Plain radiographs of the knees show joint space narrowing, osteophyte formation at the margins, subchondral sclerosis, and subchondral cyst formation. There is no evidence of erosions or soft tissue swelling. MRI of the right knee reveals cartilage loss, bone marrow edema in the femoral condyle, and a 1.5 cm subchondral cyst. What is the most likely diagnosis based on these imaging findings?

Which radiographic finding is pathognomonic for rheumatoid arthritis and typically appears earliest in the disease course?