The angle of knee flexion is a key outcome
measure in surgery of the knee.
The accuracy of measurement of this angle
is, however, hampered by the cross-
sectional anatomy of the femur which makes
the identification of boney landmarks difficult.
The new generation of Apple® Portable
devices contain accelerometers which
enable angles to be measured in
relation to the vertical (by measuring
the acceleration of g).
The Tibia has a subcutaneous border and it
is therefore relatively easy to measure its inclination
in this way:
In the morphologically typical adult the femoral
and tibia segments have a predictable relationship-
The femoral segment is 1.2 times the length
of tibia segment.
?=180-(γ+α)
Thus, using trigonometry it is possible to calculate
the angle of knee flexion from the angle of tibial
inclination:
Knee Goniometer
