ig. 1. Schematic of the FE model with three different displacement constraints: (a) Linear model with a non-friction slider on the greater trochanter which was free to translate in x and y directions; the distal end was completely fixed. (b) MPC model with non-friction slider on the greater trochanter which was free to translate in x and y directions while the distal end connected to a pilot node by a multi-point constraints (MPC) method; the pilot node was free to rotate around z axis. (c) Contact model with nonlinear surface-to-surface contact between the greater trochanter and an infinitely rigid plate representing the ground. MPC elements were used to connect the distal end of the femur and the pilot node, which was free to rotate around the z axis.