Biomechanics of the hip joint in children

Abstract

Based on the data derived from the examination of 16 infantile and juvenile anatomical hip specimens as well as the radiological examination of 1350 hip joints of healthy children, a biomechanical model of the developing hip was computed. This two-dimensional vector model describes the forces acting on the growth plates of the head and the greater trochanter during the one-legged stance. It could be proven that the apophysis of the greater trochanter is subject to compressive stress by lateral-cranial traction bands and therefore corresponds with a "pressure apophysis". The muscle forces acting on the trochanter apophysis can be combined as a trochanteric resultant RT. This stimulates a lateral-cranial growth of the trochanter apophysis. The direction of the hip abductors and, as a result, also the direction and the length of Pauwels' hip resultant R are influenced by this mechanism.