Figure 2.
Translations and rotations are expressed based on a coordinate system with the tip of the prosthesis as origin. Positive translations along the X-axis correspond to medial migration, those along the Y-axis to proximal migration, and those along the Z-axis to anterior migration. Positive rotations about the X-axis correspond to anterior tilt, those about the Y-axis to retroversion, and those about the Z-axis to valgus.
