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Musculoskeletal Imaging

E2843. The Metacarpophalangeal Joint, Up Close and Personal

Saif M1,  van Holsbeeck M2,  Chapin R3,  Conway W3,  Davis L.3 1. Touro College of Osteopathic Medicine, New York, NY; 2. Henry Ford Hospital, Detroit, MI; 3. Medical University of South Carolina, Charleston, SC

Address correspondence to L. Davis (davislea@musc.edu)

Background Information: MRI has been used to evaluate the stabilizing structures around the metacarpophalangeal (MCP) joints of the fingers, including the ulnar and radial collateral ligaments, volar plate, flexor tendons and extensor apparatus. In the setting of trauma, both acute and chronic, MRI can evaluate the integrity of these structures. In the setting of inflammatory arthropathy, MRI and ultrasound (US) are currently used for detection of synovitis, joint effusions and osseous erosions but, to our knowledge, these imaging modalities have never been specifically utilized to evaluate changes of the stabilizing structures around the MCP joints in the setting of rheumatoid arthritis. Rheumatoid arthritis is a chronic inflammatory disease that most commonly affects small joints of the hands and feet, including the MCP joints of the fingers. Inflammation within and around the MCP joints can lead to destruction of periarticular stabilizing structures, resulting in joint instability. Initially, patients with rheumatoid arthritis often compensate for pain but over time, particularly if left untreated, permanent damage to the MCP joint can lead to ulnar deviation and significant debility. Previous studies have demonstrated that failure to detect early MCP instability results in delayed referral to hand surgeons. Early identification of abnormalities involving the stabilizing structures of the MCP joints on MRI or US may allow for better collaboration among rheumatologists, radiologists, and hand surgeons and may prevent debilitating deformity at the MCP joints.

Educational Goals/Teaching Points: We present graphics with corresponding radiology images of the stabilizing structures around the MCP to identify normal MRI and US appearances of these small structures. We also present MRI and US examples of pathology involving the stabilizing structures around the MCP joints in patients with rheumatoid arthritis. Technical guidelines for MRI and ultrasound of the MCP joint vary and can result in marked differences in visualization and interpretation of the microanatomy around the MCP.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques: Although MRI is currently being used to image the MCP joints, the diagnostic focus of previous studies has been on traumatic injury to the structures. In our exhibit, we will present MR findings around the MCP in patients with rheumatoid arthritis. Anatomy and pathology will be presented with illustrations and corresponding MRI and US images. Propose MRI and US imaging protocols and tips for improved visualization and diagnosis of pathology involving the stabilizing structures around the MCP joints.

Conclusion: Identifying and scrutinizing the stabilizing structures around the MCP joints on MR or US imaging may allow radiologists to identify abnormalities early, perhaps even before instability is appreciated on examination. Ideally, this information will lead to earlier diagnosis, close monitoring, and prompt treatment to delay or prevent destruction and instability at the MCP joints in patients with rheumatoid arthritis.