Figure 1.

X-ray pelvis with both hip joints anteroposterior view showing importance of mediolateral position in determining joint reaction force. Medialization reduces body weight lever arm and increases abductor lever arm reducing joint reaction force which is calculated as JRF = BWxB – AbxA. Right side shows femoral offset, acetabular offset, and their contribution to global offset. BW – Body weight, Ab – Abductor force, A – Abductor moment arm, B – Body weight moment arm, JRF – Joint reaction force, AO – Acetabular offset, FO – Femoral offset