Articular coronal fracture angle of posteromedial tibial plateau fragments: A computed tomography fracture mapping study

Abstract

Objectives: The purpose of this study is to analyze posteromedial fragment morphology using two-dimensional computed tomography fracture mapping and to compare posteromedial fragment morphology in various Schatzker type tibial plateau fractures.

Materials & methods: One hundred twenty-seven consecutive AO/OTA B- and C-type tibial plateau fractures were retrospectively analyzed using 2DCT fracture mapping. The posteromedial articular fracture angle and articular surface areas of all fractures with posteromedial fragments were calculated. Based on biomechanical studies, posteromedial fragments with coronal fracture angles >68° were considered amenable for anterolateral stabilization with standardized plating. Kruskall-Wallis non-parametric test was used for statistical comparison of morphological features of posteromedial fragments between the various Schatzker types.

Results: Forty-seven out of 127 tibial plateau fractures included a posteromedial fragment. The mean posteromedial articular fracture angle was 44° (range: 2°-90^o, standard deviation: 23°). Forty fragments (85%) had a fracture angle of <68°, increasing the risk for insufficient stabilization with standardized anterolateral plating. The mean articular surface area was 34% of the entire tibial plateau (range: 7%-53%, SD: 12%). There were no significant differences in posteromedial fragment morphology between Schatzker type IV, V, and VI fractures.

Discussion and conclusion: Posteromedial fragments commonly occur not only in Schatzker type V and VI, but also in Schatzker type IV tibial plateau fractures. Eighty-five percent of tibial plateau fractures with a posteromedial fragment may benefit from non-standard customized lateral plating, or may require an additional medial or posterior surgical approach for fracture-specific fixation to optimize screw purchase and biomechanical stability.

Keywords: Computed tomography; Fracture mapping; Knee; Morphology; Posteromedial fragment; Tibial plateau fracture; Trauma.