Figure 4

Algorithm-based identification of proximal and distal femoral and tibial reference lines to determine lower limb torsion. (a) At the hip, the femoral head centre was identified and used to define the femoral neck axis that served as the proximal femoral reference line. (b, c) Around the knee, the most posterior extensions of the medial and lateral femoral and tibial condyles were identified and connected as the distal femoral (b) and proximal tibial reference lines (c). (d) At the ankle, the tibial and fibular centroids were connected as the distal tibial reference line. RL reference line. MR images are not to scale.