Biomechanical impact of severe genu valgum (18°) on the lateral meniscus: a finite element stress analysis

Genu valgum is a deformity that alters load transmission in the knee. While the effects of mild deviations are known, the specific quantitative impact of severe deformities (>15°) on the lateral meniscus remains understudied. This research aims to quantify the stress distribution in a severe 18° valgus deformity compared to a healthy morphology. A comparative Finite Element Analysis (FEA) was conducted. 3D models were reconstructed from segmented DICOM images using MIMICS and 3MATIC software. A static vertical load of 850 N, simulating a bipedal stance, was applied to both a healthy model and a pathological model with an 18° axial deviation. The simulation used a high-order 20-node quadratic mesh to ensure accurate capture of stress gradients. The healthy knee exhibited a maximum Von Mises stress of 2.76 MPa, distributed homogeneously. In contrast, the pathological model showed a critical stress concentration of 17.54 MPa in the lateral meniscus. This represents a 535% increase, demonstrating a non-linear exponential rise in stress compared to milder deformities reported in the literature. An 18° valgus deformity subjects the lateral meniscus to stress levels exceeding physiological fatigue limits, confirming the mechanism for the rapid onset of lateral unicompartmental osteoarthritis. These findings suggest that conservative therapies are biomechanically insufficient for such degrees of deformity, validating the necessity for corrective osteotomy and the use of FEA as a preoperative planning tool.