From Measurement to Interpretation - Kinematic Analysis of Human Movement - page 51

For example, let us explain the hip joint. The anatomical
landmarks used are the antero-superior (ASIS) and postero-
superior (PSIS) iliac spines on the pelvis, the medial and
lateral epicondyles (MFE, LFE) and the center of the femoral
head on the femur. For this final point, palpation clearly
cannot be used and it is therefore defined either from
regression equations [BELL 90, DAV 91, SEI 95] or,
preferably, by functional methods [CAP 84, CHE 96,
LEA 99]. From these points, the coordinate systems of the
pelvis and femoral segments are formed as follows [CAP 95]:

:
- : the origin coincides with the center of the femoral
head;

, ,

- Pelvis ,

: the axis parallel to the line passing through the
ASIS iliac spines, pointing toward the right;

-

in the plane formed by
the ASIS iliac spines and the middle point of the PSIS iliac
spines, pointing forward;

: the axis perpendicular to

-

: the axis perpendicular to and forming a

-

direct trihedron, pointing upwards.

:
- : the origin coincides with the center of the femoral
head (therefore coinciding with the origin of the Pelvis
coordinate system);

- Femur , , ,

: the axis joining the middle point of the medial and
lateral epicondyles and the origin , pointing upwards;

-

in the plane formed by
the origin and the two epicondyles, pointing to the right;

- : the axis perpendicular to

: the axis perpendicular to and forming a direct

-

trihedron, pointing forwards.