Ultrasound guidance allows accurate needle placement and aspiration from small joints in patients with early inflammatory arthritis

Objectives. To compare the accuracy of palpation-guided and high frequency ultrasound-guided needle placement in small joints and to develop a technique to obtain synovial fluid from these joints for diagnosis and research. Methods. The accuracy of needle placement during palpation-guided proximal interphalangeal (PIP) or metacarpophalangeal (MCP) joint injection was assessed. This was compared with the accuracy of ultrasound-guided needle placement. A joint lavage technique was developed to obtain synovial fluid from these joints. Results. Needle positioning was intra-articular in 59% of palpation-guided injections (6/12 PIP and 4/5 MCP joints). No fluid could be aspirated prior to injection. With ultrasound guidance, initial needle placement was intra-articular in 96% of cases (24/26 PIP and 27/27 MCP joints). Synovial fluid cells were lavaged from 63% of joints (19/25 PIP and 14/27 MCP joints). In only one case was a large effusion seen and this was aspirated directly. Conclusions. The use of high frequency ultrasound to guide needle placement within a small joint allows for significantly greater accuracy than a palpation-guided approach. When followed by lavage, synovial fluid cells and diluted synovial fluid can be obtained from the majority of small joints. This has important clinical and research implications.