The ABC Algorithm for Staging Scaphoid Nonunions

Abstract Scaphoid nonunion is a common and disabling condition in wrist surgery, associated with high rates of instability, chronic pain, and progressive degenerative changes. Due to the scaphoid's unique vascular anatomy and complex biomechanics, treatment decision-making remains challenging, and standardized staging protocols are lacking. Current imaging modalities alone often fail to provide sufficient accuracy in evaluating key parameters such as stability, vascularity, and associated ligament or cartilage injuries. This study introduces and evaluates a new pre- and intraoperative classification system—the ABC algorithm—which integrates preoperative imaging with arthroscopic findings to stage scaphoid nonunions more accurately and reproducibly. The ABC algorithm categorizes scaphoid nonunions based on three components: (A) associated ligament injuries, (B) bone characteristics (including defect size, stability, fragmentation, and vascularity), and (C) cartilage status. Arthroscopic evaluation was performed systematically, using standardized portals and validated diagnostic techniques such as the hook test, rocking chair sign, and Outerbridge/International Cartilage Repair Society cartilage grading. A novel five-type arthroscopic bone classification was proposed based on stability, defect size, bleeding, and proximal pole fragmentation. Arthroscopy enabled direct, minimally invasive evaluation of joint integrity, providing reliable differentiation between stable and unstable nonunions, and precise identification of cartilage lesions and ligament injuries. The algorithm also provided immediate assessment of bone vascularity, a crucial determinant of prognosis and treatment approach, particularly in selecting between structural and vascularized bone grafts. The classification proved applicable even in revision surgeries, demonstrating adaptability across surgical expertise levels. The ABC algorithm is a simple, comprehensive, and practical staging system for scaphoid nonunion that combines the strengths of advanced imaging and wrist arthroscopy. By providing detailed insights into articular, ligamentous, and osseous pathology, it enables better-informed surgical decisions and facilitates outcome comparisons in future multicentric studies. While further validation is warranted, this algorithm holds promise as a standard reference for both open and arthroscopic management of scaphoid nonunion.