유한요소 분석법을 이용한 거골하 관절 유합술에서 이상적인 고정 나사의 위치 - 유한 요소 해석

Abstract

Purpose: The subtalar arthrodesis using screw has been performed to manage traumatic subtalar arthritis that requires operative treatment. This investigation aimed to assess the optimal configuration of double screw fixation for subtalar arthrodesis. Materials and Methods: From the CT scanned images of an ankle of a Korean male (21 year old), polygon models of the talus and calcaneus were reconstructed. The polygon models were converted to tetrahedron finite elements. Young？Ss modulus was assigned locally to each element based on the Hounsfield Unit, and a Poisson？Ss ratio of 0.4 was used commonly. Four fixation configuration models of double screw subtalar arthrodesis were designed according to the talar placement of a dome screw, i.e. anterolateal (AL), anteromedial (AM), posterolateral (PL), and posteromedial (PM) while the placement of a neck screw is fixed. External and internal rotation torques of 4 N-m were applied to calculate stability of each fixation configuration. Results: For the fixation configuration of a neck plus a PM dome screw, the displacements of a posterior calcaneus was 0.91 mm and 0.85 mm under external and internal rotation torques of 4 N-m, respectively, which were less than for other configurations. As well, the fixation configuration of a neck plus a PM dome screw showed least rotations of 4.98 degrees and 4.84 degrees, respectively for external and internal torques. Conclusion: A combination of a neck screw and a posteromedial dome screw is expected to provide the best rotational stability for subtalar arthrodesis.

Key Words : Ankle, Subtalar arthrodeis, Screw fixation, Finite Element