Transmission ultrasonography showing a distended joint capsule in the proximal interphalangeal joint (arrow) of a patient with rheumatoid arthritis.
Reproduced from: Owen DS. Aspiration and injection of joints in soft tissue. In: Textbook of Rheumatology, 4th ed, Kelley WN, Harris ED Jr, Ruddy S, et al (Eds), WB Saunders 1993. p.545.