Biomechanical comparisons of plate placement for medial tibial plateau fractures (Schatzker type IV): A biomechanical study using porcine tibias

Biomechanical studies on medial tibial plateau fractures (MTPFs) (Schatzker classification type IV) are currently few, while studies using locking plates (LPs) placed on medial proximal tibias are unavailable. Hence, we compared the biomechanical properties of plate osteosynthesis at the medial and anteromedial placements using large- and small-fragment LPs in porcine bones.MTPFs were internally fixed using LPs on 40 porcine tibias. Specimens were equally divided into four groups: medial placement using a large-fragment LP (LPs for the medial (LM) group), anteromedial placement using a large-fragment LP (LAM group), medial placement using a small-fragment LP (SM group), and anteromedial placement using a small-fragment LP (SAM group). The translation patterns of the constructs in each group were examined by cycling loading test (displacement and translation along the mechanical axis at 10-100, 100-500, 500-1000, 1000-1500, and 1500-2000 cycles). Then, articular gaps and step-off changes after 2000 cycles were compared among the four groups.One-way analysis of variance (ANOVA) revealed no significant differences in displacement and translation during cyclic loading. One-way ANOVA followed by post hoc analysis revealed that the anterior gap was lower in LPs for the medial (LM) than in SM (P = 0.029) and SAM (P = 0.0026). The central gap was also lower in LM than in SM (P = 0.042) and SAM (P < 0.001), and it was lower in LAM than in SAM (P = 0.047). Likewise, the posterior gap was lower in LM than in LAM (P = 0.025) and SAM (P < 0.001). Furthermore, the central step-off of SAM was higher than that of LM, LAM, and SM (P < 0.001, P = 0.0014, and P = 0.0077, respectively). The posterior step-off was lower in LM than in SAM and LAM (P = 0.037 and P < 0.001), and it was also lower in SM than in SAM (P = 0.0082).Medial LP placement for MTPFs in porcine bones resulted in significantly lower posterior step-offs after cyclic loading than anteromedial placement, and large-fragment LPs for MTPFs caused significantly lower fracture gaps in the central articular after cyclic loading than small-fragment LPs.