• Line between the
center of the femoral
head and the center of
the knee joint (between
both femoral condyles).
- Lines represent the
orientation of the joint in
certain plane.
- Knee Joint
- Along the subchondral line of
the tibial plateau.
- Line tangential to the most
distal point of the femoral
condyles.
Normally joint lines are parallel within 2
degrees.
Angles greater than 2 degrees are
considered as a source of mechanical axis
deviation (MAD).
-Angle between:
-Line along the
mechanical axis of the
femur and line along
the distal point of the
femoral condyles
- Normal range is 85-
90 degrees.
-Angle between:
-Line along the
mechanical axis of
the tibia and line
along the tibial
plateau.
- Normal range is
85- 90 degrees.
In cases of deformity:-- Angle between the distal tibial mechanical axis and
line along the tibial plafond.
- If one side is normal then it is used as a template
for the deformed site.
- If both are deformed then consider normal angles.
- (Center of rotation angle).
- Point at which proximal and distal axis
lines intersect.
- Osteotomy fracture is done at CORA site.
1- Measure mechanical
axes of both lower limbs.
2- Joint orientation lines.
3- LPFA and MPTA/LDTA.
4- CORA.