Use of Ultrasound by Internists to Improve Diagnostic Small Joint Aspiration.

BACKGROUND: Primary care internists are often the first to see patients with an initial episode of crystalline arthritis. Timely aspiration of the affected joint for definitive diagnosis and treatment in the office is desirable but can be difficult, especially if the joint is small, surrounded by soft tissue swelling distorting landmarks, and is very painful to move or palpate.

METHODS: We compared the likelihood of successful aspiration of the great toe metatarsophalangeal joint by primary care internists for the diagnosis of potential crystalline arthritis by either landmark identification of the joint space or by employing ultrasound to identify the joint space.

RESULTS: Aspiration was performed by one of 2 primary care internists using landmarks and palpation to identify the joint space in 27 patients with suspected crystalline arthritis affecting the first metatarsophalangeal joint. A sample adequate for diagnosis by polarized light microscopic crystal analysis was obtained in 14 of the 27 aspirations (52%) when landmarks alone were used to locate the joint space. In an additional 27 patients with suspected crystalline arthritis affecting the first metatarsophalangeal joint, ultrasound was used to identify the joint space and resulted in a significant increase in the success of obtaining an adequate diagnostic sample, which was obtained in 25 of the 27 aspirations (93%).

CONCLUSIONS: The primary care internist can easily provide quality and timely small joint diagnostic aspiration when ultrasound is used to identify the location of the joint space.