Biomedical Engineering Reference
In-Depth Information
4.3. Error in locating anatomical landmarks
To correctly interpret joint kinematics, it is important to
accurately define the anatomical landmarks, which will form
the basis for the construction of orthonormal coordinate
systems linked to adjacent body segments, and then
the “Joint Coordinate System” (see Chapter 3). The
literature review by Della Croce
et al
. [DEL 05] provides a
detailed analysis of available information with regard to the
accuracy of the positioning of anatomical landmarks,
whether subcutaneous (such as knee epicondyles) or
internal (such as the center of the femoral head), as well as
the sensitivity of joint kinematics to errors in this
positioning.
4.3.1.
Assessment
With regard to the positioning of subcutaneous
anatomical landmarks, the error sources correspond, on the
one hand, to the fact that these “reference points” are not
actually points but rather large bony surfaces and their
determination depends, therefore, on the palpation
technique used. On the other hand, palpation is often
difficult due to the thickness of the adipose tissue of the
subject analyzed. Thus, the positioning of these points is
both operator- and subject dependent. The intra- and
interoperator variability of this positioning has been
assessed in several studies, for landmarks on the hand or
wrist [SMA 93] or lower limb [DEL 99, RAB 02]. For certain
landmarks, such as iliac spines and the greater trochanter,
the variability is high, of approximately 15-20 mm, whether
it is intra- or interoperator.
For internal anatomical landmarks, since the use of
imaging is incompatible with a routine clinical protocol, two
possible approaches include, on the one hand, using
