Summary

This study investigates the biomechanical impact of medial open wedge versus lateral closed wedge high tibial osteotomy on posterior tibial slope and stress distribution within the tibiofemoral joint. Results highlight that combining medial meniscus posterior root repair with lateral closed wedge HTO more effectively reduces stress and optimizes joint biomechanics compared to isolated HTO.

Abstract

Introduction： High tibial osteotomy (HTO) is widely used to correct varus knee deformities and improve joint biomechanics. A medial meniscus posterior root (MMPR) tear (MMPRT) compromises the circumferential integrity and stability of the medial meniscus, resulting in development of the knee osteoarthritis. At present it remains controversial whether isolated HTO or MMPR repair combined with HTO is a better surgical strategy for patients with MMPRTs. There is a lack of studies that evaluated the influence of medial opening wedge high tibial osteotomy (MOWHTO) vs lateral closing wedge high tibial osteotomy (LCWHTO) on stress distribution in the MMPR. This study aimed to investigate the biomechanical effect of different surgical techniques, specifically HTO and its combination with MMPR repair, on the tibiofemoral joint and MMPR using three-dimensional (3D) finite element analyses (FEA).
Methods： This study involved a 32-year-old male volunteer (180 cm, 90 kg) without a history of knee injury who underwent CT and MRI imaging of the knee joint. The CT and MRI data were imported into MIMICS software to generate 3D knee models. A senior orthopedic surgeon integrated these models using 3-matic software and imported them into SolidWorks software for surgical simulation. This study simulated a total of six knee conditions as follows: (1) intact MMPR; (2) MMPRT; (3) MMPRT with MOWHTO; (4) MMPRT with LCWHTO; (5) MMPR repair combined with LCWHTO; (6) MMPR repair combined with MOWHTO. MOWHTO and LCWHTO were created using three symmetrical osteotomy methods, with the mechanical axis shifting to the Fujisawa point after HTO. The ankle center was fixed, and a 1000 N force was applied to the knee joint. These models were then subjected to biomechanical FEA simulations to evaluate the biomechanical effect of each surgical strategy on MMPR.

Results

The posterior tibial slope (PTS) decreased by 3.1°, 1.0°, and 0° in the three LCWHTO models, whereas it increased by 3.1°, 1.0°, and 0° in the three MOWHTO models. The PTS variations significantly influenced the stress distribution in the MMPR. LCWHTO, which flattened the PTS, reduced von Mises stress (VMS) and shear stress in the MMPR by 3.8%-33.1% and 3.4%-26.5%, respectively. Conversely, MOWHTO, which steepened the PTS, increased VMS and shear stress by 10.9%-46.5% and by 11.5%-45.0% in the MMPR, respectively. MMPR repair combined with HTO decreased maximum contact stress by an average of 8.3% and increased the contact area by an average of 37.5% in the medial knee compartment compared to isolated HTO.

Conclusions

This study showed that LCWHTO and MOWHTO had a different influence on the VMS and shear stress in the MMPR, partly because of the change of the PTS following HTO. In addition, MMPR repair combined with HTO revealed more protective results against in the medial knee compartment contact stress compared to isolated HTO. These findings suggest that MMPR repair combined with LCWHTO may be superior to MMPR repair combined with MOWHTO or isolated HTO from a biomechanical viewpoint of the status in the tibiofemoral joint and MMPR.