Biomechanics of the proximal end of the femur during growth

Mechanical factors have a strong influence on the growth and development of the skeleton [1], [2]. Forces acting on the growing bones play an important role in their forming process. Disturbances of such loadings in the prenatal period as well as during infancy and childhood can lead to serious developmental deformities [3]. Proximal end of the femur is one of the main parts of the hip joint. The head placed at the end of the neck is the most proximal part of the femur. The axis of the neck is directed superomedially towards the shaft axis in the frontal plane (neck-shaft angle) and anteriorly towards the condylar axis in the transverse plane (anteversion angle). Greater and lesser trochanters are situated at the basement of the neck. Geometry of the proximal end of the femur is very important for the hip joint biomechanics. During development, growth of the bone is sustained mainly by the chondral epiphyses. Secondary ossification centres, successively occurring in the cartilage, change the structure and biomechanics of the growing epiphyses and lead to forming of the growth plates. In the proximal femur, three ossification centres appear during development: the first is located inside the head, the second occurs in the greater trochanter and the third in the lesser trochanter. Growth plates which insulate trabecular metaphysis from ossifying head (capital epiphyseal plate) and trochanters (trochanteric epiphyseal plates) are active till puberty and allow femoral neck elongation as well as regulation of the neck-shaft and the anteversion angles [4], [5]. The size and shape of the femoral head is formed by activity of the growth cartilage located outside the secondary ossification centre, just below the external layer of articular cartilage. The aim of the presented research was to perform a biomechanical analysis of the growing proximal end of the femoral bone. Numerical simulation of this structure should allow a better understanding of the bone development in normal conditions as well as in pathological cases.