Stress analysis of the growing femur: effects of frontal axial deviation

Both the pathogenesis and the evolution of lower limb deformity secondary to primitive axial deviation during the growth period are affected by biomechanical factors which direct the remaining skeletal growth along abnormal lines. This study, limited to the femur, aims to analyze these factors from a practical as well as abstract standpoint, with references to prevention and surgical treatment. For this biomechanical study the authors applied finite element analysis to 16 models of the femur with various deformities in the frontal plane--proximal, distal, valgus, and varus. Analysis of the results shows significant variations in the physiologic status of stress on the femur associated with axial deviation in the frontal plane. These variations have special characteristics according to the type and level of the deviation. Furthermore, the stress imbalances seem to be concentrated in the distal metaphyseal region, even in cases of proximal deformity.