Scaphoid Malunion and the Risk of Degenerative Arthritic Wrist: A Narrative Review of Biomechanics and Clinical Outcomes

Scaphoid malunion is a common radiographic outcome following scaphoid fracture healing and has traditionally been assumed to predispose patients to degenerative wrist arthritis, often by analogy to scaphoid nonunion advanced collapse (SNAC). However, the clinical relevance and natural history of scaphoid malunion remain incompletely defined. This narrative review synthesizes the literature addressing radiographic definitions, biomechanical consequences, clinical outcomes, and reported management strategies for scaphoid malunion, with particular emphasis on its proposed relationship to SNAC wrist. Available studies demonstrate substantial heterogeneity in radiographic criteria used to define malunion, most commonly involving intrascaphoid angle, humpback deformity, and scaphoid length or alignment. Biomechanical investigations show altered wrist kinematics and load distribution in malunion; however, preservation of osseous continuity distinguishes malunion fundamentally from nonunion and does not reproduce the carpal instability patterns characteristic of SNAC. Importantly, clinical outcome studies do not consistently demonstrate increased pain, worse functional outcomes, or higher rates of secondary intervention in patients with scaphoid malunion compared with well-aligned unions, and progression to symptomatic degenerative arthritis is not reliably observed. Reported treatment strategies range from observation to corrective osteotomy and salvage procedures, with outcomes largely determined by patient symptoms and clinical context rather than radiographic deformity alone. Overall, current evidence suggests that scaphoid malunion represents a heterogeneous condition in which radiographic deformity and biomechanical alteration do not reliably predict clinical deterioration or inevitable progression to SNAC wrist, supporting a cautious, individualized, and symptom-driven approach to management.