Stress-specific differences in Distal Femoral Epiphysis of Leg Length Discrepancy and Pelvic Tilt. A Finite-Element Analysis

Abstract

Objective This study aimed to compare the distal femoral epiphyseal stress of Leg Length Discrepancy and Pelvic Tilt, to explain the phenomenon of genu varum and genu valgum in children with unequal lower extremities or pelvic tilt. Methods The finite element models was established to analyze the distal femoral epiphyseal Equivalent Von Mises Stress, We reconstructed the right sacrum, pubis, ischium, and femur of a healthy child by finite element method, and generated the distal femoral epiphysis and other cartilage structures. The left femur was amputated (1, 2, 3, 4, 5, 6cm) to study the stress changes in the bilateral distal femoral epiphysis. In addition, we tilted the pelvis of four models and placed the distal femur at the same level to study the stress changes after the pelvis was tilted. Results The Equivalent Von Mises Stress distribution of the distal femoral epiphysis on both sides of the children with unequal lower limbs was uneven, and the stress stimulation on the lateral side was greater than that on the medial side. And when the pelvis is tilted, this stimulation is more obvious. Conclusions We reconstructed a healthy child's pelvis and femur by Finite-Element, including cartilage and epiphyseal structures. The left femur was amputated to simulate the Leg Length Discrepancy, the pelvis tilt was also studied. Both lead to the increased lateral stress, with pelvic tilt having a greater effect.