Resultant hip joint force after total hip replacement.

Bending moments acting on the LIMA-LTO femoral stem were calculated using a 3D mathematical model of the hip in the one-legged stance based on muscle anatomical data. The effects of 1 cm medialization and lateralization of the hip joint rotation centre (RC) on the bending moments were determined for different body weights. It was found that the bending moments and hence the stem loosening incidence are higher in lateralization compared to medialization of the RC. In order to diminish the bending moments, body weight should be reduced.