Effect of plate design on maintenance of anterior and posterior gaps and posterior tibial slope after cyclic loading in medial open-wedge high tibial osteotomy: A biomechanical study using porcine's tibia.

ABSTRACT

Purpose: We aimed to investigate whether a plate adapted to the anatomy of the proximal medial porcine's tibia would provide maintenance of the anterior gap (AG), posterior gap (PG) and posterior tibial slope (PTS). Methods: Twenty-seven porcine tibias were biomechanically evaluated by performing MOWHTO and placing TOMOFIX (n = 9), AC plate (n = 9) and TriS (n = 9) anteromedially. Cyclic testing (800 N, 2000 cycles, 0.5 Hz) was performed to investigate the PTS over time for MOWHTO. The particular displacement calculated from the maximum to the minimum point with the load-displacement curve along the mechanical axis during cyclic testing, the final AG and PG changes at the osteotomy site, the increased PTS calculated by subtracting AG from PG after 2000 cycles were compared among the three groups. The displacement was evaluated by repeated-measures analysis of variance (ANOVA), and changes in AG and PG and increased PTS were evaluated by one-way ANOVA. The sample size for α and ß errors were <0.05 and <0.20, and the effect size was 0.64 for one-way ANOVA and 0.49 for repeated-measures ANOVA. Results: There were no significant differences in displacement among the groups. A significant difference was observed in the AG (p = 0.044) and PG (p = 0.0085) changes. There were no significant differences in increased PTS among the groups. Conclusion: When anteromedially placed, the AC plate and TriS resulted in significant maintenance of AG and PG compared with that of TOMOFIX in MOWHTO after cyclic loading. Level of Evidence Level Ⅳ.