Increased posterior tibial slope leads to altered pressure distribution in the lateral tibial plateau-A biomechanical in-vitro study.

Abstract

Purpose: The aim of this study is to investigate the impact of increased posterior tibial slope (PTS) on pressure distribution in the medial and lateral tibial plateau. The focus is on compartment-specific effects and potential correlations with cartilage damage, due to altered anterior tibial translation caused by increased PTS.

Method: Ten freshly frozen knee specimens were prepared and subjected to biomechanical testing. PTS was modified by inserting 5°, 10°, 15° and 20° polylactic acid wedges into osteotomy gaps. Pressure distribution was measured using Tekscan's Pressure Mapping Sensor 5040™ beneath the menisci at varying PTS angles. The kinetic data were tracked using the Optotrak Certus® system. Statistical analyses were employed to evaluate the pressure shifts and their significance.

Results: The study revealed that increased PTS significantly shifted the pressure point anteriorly on the lateral tibial plateau, while no significant changes were observed on the medial plateau. The analysis of tibial translation showed a corresponding rise in anterior translation with increasing PTS, especially at higher angles.

Conclusion: Increased PTS, particularly above 10°, induces significant anterior translation and altered pressure distribution, primarily affecting the lateral tibial plateau. These findings support the hypothesis that elevated PTS contributes to biomechanical stresses in the knee, potentially increasing the risk of lateral compartment cartilage degeneration. These results highlight the importance of considering PTS in clinical assessments and interventions aimed at optimizing knee joint health.

Level of evidence: Level IV.