Grood and Suntay: functional knee axis or anatomical axis?

[Maryam Hajizadeh]

I am just working on knee kinematics and I want to apply Grood and Suntay method for my kinematic analysis. Some references use the axis calculated from skin markers as the input for Grood and Suntay. For example, they take the line connecting the epycondyle markers as the first axis for knee kinematics. However, some prefer to use functional knee axis as the first axis (for example the helical axis, SARA axis,...). I want to know what are the advantages and disadvantages with each of them? and with which of these, I can have more accurate results?



Thanks,
Maryam