20
Femoral Condyle Rotational References
Based on surgeon preference, there are three
options on which the femur rotational reference
frame can be defined . These rotational references
are used during Implant Planning (Section 6) for
component placement onto the patient anatomy. It
is important to understand how these collections
are taken on the patient’s bony anatomy so that
they may be referenced properly during planning.
(Figures 26-29)
•
Transepicondylar Axis Collection
If the epicondyles are selected as the preference
for rotational reference collection, mark the medial
and lateral epicondyles on the femur, which will
be used to create the medial-lateral axis for the
femur. The AP axis is then derived from the femur
mechanical axis and the ML axis defined in this
stage.
•
Femoral AP Axis Collection
While the other collections listed are singular
points referencing the tip of the point probe,
this collection will reference the axis of the point
probe. If Femoral AP Axis is selected for rotational
reference collection, using the length of the pointer
probe, collect the AP axis for the femur, normal to
the transepicondylar axis. This collection, along
with the femur mechanical axis will define the
medial-lateral axis of the patient’s femur.
Figure 26.
Figure 27.
4
Registration
