Bioplating demonstrates increasing micromovement during cyclic loading after anterior closed wedge high tibial osteotomy despite no significant difference in failure load compared to angle-stable plate fixation.

PURPOSE: To biomechanically compare fixation stability after anterior closed wedge high tibial osteotomy (ACW-HTO) for posterior tibial slope (PTS) correction using trans-tuberosity "bioplating" and infra-tuberosity angle-stable plate fixation. METHODS: In this cadaveric biomechanical study, fresh-frozen human knee specimens were allocated in a paired donor-matched manner to the two intervention groups. Tensile load was applied to the quadriceps tendon at a fixed flexion angle using an electrodynamic testing machine. After preloading, 1000 load cycles between 50 N and 200 N were performed at 1 Hz. The specimens were then loaded to failure at 10 mm/s. Micromovement at the osteotomy gap was analysed after 200 and 800 cycles using an optical 3D system. Two-way ANOVA with Bonferroni multiple comparison testing was used, with p < 0.05 considered statistically significant. RESULTS: Twelve cadaveric knee specimens (n = 6 per intervention group; mean age 79.2 ± 8.2 years) were included. No statistically significant difference in micromovement was found between the two intervention groups after 200 (p = 0.515) or 800 cycles (p = 0.889). In the "bioplating" group, micromovement increased from 0.055 ± 0.017 mm after 200 cycles to 0.069 ± 0.035 mm after 800 cycles (p = 0.025), whereas no significant increase occurred with angle-stable fixation (p = 0.518). Osteosynthesis failure load did not differ significantly between groups (643.9 ± 190.8 N vs. 566.8 ± 111.0 N, p = 0.422). CONCLUSION: No significant difference in failure load was detected between the techniques. However, "bioplating" demonstrated increasing micromovement during cyclic loading. Considering the limitations of the present biomechanical setup, superiority or inferiority of either fixation technique cannot be concluded. These findings should serve as a basis for further biomechanical testing and should be considered when selecting the surgical technique and postoperative treatment regimen in patients undergoing ACW-HTO for PTS correction. LEVEL OF EVIDENCE: Level V, controlled laboratory study.