Establishment of a finite element model and stress analysis of intra-articular impacted fragments in posterior malleolar fractures

Abstract

Background Intra-articular impacted fragments (IAIFs) are considered articular surface fragments resulting from impact and compressive forces. The malreduction of IAIFs in posterior malleolar fractures has been associated with talar subluxation and long-term post-traumatic arthritis. In this study, we establish IAIF defect finite element models of different sizes in posterior malleolar fractures and explored how IAIF defects predict the onset of post-traumatic arthritis. Methods A reliable three-dimensional finite element model of the normal ankle was established. Finite element models with different sizes of IAIF defects were created to calculate ankle joint contact stress. The finite element data were recorded and analyzed. Results There was a linear relationship between the size of the IAIF defect and MCS with IAIF defects in the posterolateral region. The result of Pearson linear correlation analysis was r = 0.963, P = 0.009. The regression equation was MCS = 0.087*AI + 2.951 (AI, area of IAIF) by simple linear regression analysis. When the IAIF defect was in the posteromedial region, there was also a linear relationship between the size of the IAIF defect and MCS. The result of Pearson linear correlation analysis was r = 908, P = 0.033. The regression equation was MCS = 0.065*AI + 1.841. The MCS was increased mainly in the border of the IAIF defect. Conclusions A small IAIF defect in the posterior malleolus will result in a high MCS, and the MCS in the posterolateral region is larger than the MCS in the posteromedial region when the size of the IAIF defect is the same. We obtain the regression equation of MCS and area of IAIF defect. This indicates that patients are more prone to post-trauma arthritis when the size of IAIF defects is more than 17.8 mm2 in the posterolateral region and more than 40.9 mm2 in the posteromedial region. Trial registration Retrospectively registered.

Finite element analysis of the intra-articular impacted fragments of posterior malleolar fractures in different regions

“…Based on these research findings, Xie utilized finite element analysis in conjunction with linear equations to estimate that a joint surface defect greater than 17.2 mm 2 would result in the maximum contact stress on the joint surface exceeding 4.5 MPa. It was also emphasized that as the defect size increases, so does the corresponding increase in maximum contact stress on the joint surface, underscoring its significance in clinical treatment [10].…”

“…IAIF is associated with prognosis of posterior malleolar fracture [6,9]. Xie et al concluded that when the defect of IAIF in the posterolateral area of the distal tibial articular surface was larger than 17.2mm 2 , patients are more likely to develop post-traumatic osteoarthritis [10].…”