Scaphotrapeziotrapezoid (STT) arthrodesis is a surgical procedure used to treat various wrist pathologies, yet its biomechanical implications remain incompletely understood. This study investigates the effects of STT fusion on wrist biomechanics using a validated finite element model. Building upon a previously validated whole-wrist finite element model developed from CT scans of a 68-year-old male type I wrist, we simulated STT arthrodesis by creating a unified bone complex comprising the scaphoid, trapezium, and trapezoid, including filled articular spaces. The model was analyzed under physiological grasping loads, examining both radial and ulnar axial load distributions and articular contact pressures at the radioscaphoid and radiolunate interfaces. The fused STT complex becomes a major load-bearing structure, while radiocarpal contact pressures at both the radioscaphoid and radiolunate interfaces show reductions compared to the healthy model. This altered load distribution pattern suggests significant biomechanical adaptations following the procedure. The comparative analyses between healthy and fused models provide valuable insights into post-surgical wrist mechanics, potentially aiding surgical planning. Our findings contribute to the understanding of post-arthrodesis carpal load transfer mechanisms and their clinical implications.