Thumb Metacarpophalangeal Joint - Part II: Pathologies and Imaging Findings.

ABSTRACT: Pathologies of the thumb metacarpophalangeal joint (MCPJ) frequently affect both the general population and high-level athletes. Early and accurate diagnosis of injuries involving the stabilizing structures of the thumb MCPJ is essential for effective treatment. Delayed or missed diagnosis, as well as inadequate management, can lead to joint instability, osteoarthritis, and functional impairment. Initial evaluation includes standard static and dynamic radiographs under fluoroscopy. Computed tomography (CT) and cone-beam CT (CBCT) provide detailed analysis of osseous structures. High-resolution dynamic ultrasound (US) is the preferred technique for soft tissue assessment, while high-resolution magnetic resonance imaging (MRI) offers comprehensive visualization of all anatomical elements with excellent spatial resolution. This educational review describes the pathology of the thumb MCPJ through various imaging modalities, details injury mechanisms, and highlights the role of imaging in diverse conditions such as ulnar collateral ligament (UCL) and radial collateral ligament (RCL) injuries and instabilities, trigger thumb, pulley system lesions, dislocations, osteoarthritis, fractures of the proximal phalanx (P1) head or base, sesamoid disorders, volar plate lesions, rheumatic diseases, and osseous or soft-tissue tumors. Practical recommendations are provided to emphasize the clinical relevance of imaging findings and offer clear guidance for their application in patient care. Early and precise diagnosis is crucial for appropriate management, thereby preventing long-term complications such as instability, osteoarthritis, and functional decline.

KEY POINTS: · Injuries of the thumb collateral ligaments require early evaluation to ensure stability.. · Trigger thumb can be promptly diagnosed using ultrasound.. · Injuries of the thumb MCPJ pulley system are primarily diagnosed using ultrasound.. · Thumb MCPJ dislocations require precise and comprehensive imaging.. · Volar plate lesions are best visualized with ultrasound, with MRI if needed..

CITATION FORMAT: · Bouredoucen H, Taihi L. Thumb Metacarpophalangeal Joint - Part II: Pathologies and Imaging Findings. Rofo 2026; DOI 10.1055/a-2830-5647.