[Biomechanics of the hip joint in children]

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.