New concept in durability improvement of hip total joint endoprostheses.

Starting from the well-known fact that the rolling movement always has a lower friction compared to sliding friction, the authors have conceived and realized a pivoting movement joint on a "layer of balls" with "compensation space", placed between the acetabular cup and the femoral head. This technical solution allows free self-directed migration of the balls, depending on the resistance opposed, with successive occupation of the "compensation space". As a concept, the proposed technical solution excludes the existence of a cage for maintaining the relative positions of the spheres.