The Influence of Sagittal Angle of Posterior Malleolus Fracture on Ankle Joint Stability: A Retrospective Study of 120 Cases

Objective Due to the different force exerted during the posterior malleolus fracture (PMF), the difference in sagittal angle (SA) between the fracture fragments may affect ankle stability. But this aspect is less well studied and the aim of this study was to investigate the relationship between SA and the stability of PMF. Methods The imaging data of 120 patients with PMFs from January 2014 to November 2022 were collected retrospectively and reconstructed. We first measured SA, posterior fragment area (PFA) and fragment area ratio (FAR), reanalyzing the correlation of SA with PFA and FAR, respectively. To better describe the morphological characteristics of the fracture fragments, we further measured the fragment width diameter ratio (FWR), the fragment length ratio (FLR), fragment height (FH), contact area (CA), and finally carried these data into the regression model of SA versus FAR to conduct the intermediary role. Results SA was negatively correlated with PFA(s) (r = −0.583, P