Article

When using skin markers and stereophotogrammetry for movement analysis, bone pose
estimation may be performed using multi-body optimization with the intent of
reducing the effect of soft tissue artefacts. When the joint of interest is the
knee, improvement of this approach requires defining subject-specific relevant
kinematic constraints.
The aim of this work was to provide these constraints in
the form of plausible values for the distances between origin and insertion of
the main ligaments (ligament lengths), during loaded healthy knee flexion, taking
into account the indeterminacies associated with landmark identification during
anatomical calibration. Ligament attachment sites were identified through virtual
palpation on digital bone templates. Attachments sites were estimated for six
knee specimens by matching the femur and tibia templates to low-dose
stereoradiography images. Movement data were obtained using stereophotogrammetry
and pin markers. Relevant ligament lengths for the anterior and posterior
cruciate, lateral collateral, and deep and superficial bundles of the medial
collateral ligaments (ACL, PCL, LCL, MCLdeep, MCLsup) were calculated. The effect
of landmark identification variability was evaluated performing a Monte Carlo
simulation on the coordinates of the origin-insertion centroids. The ACL and LCL
lengths were found to decrease, and the MCLdeep length to increase significantly
during flexion, while variations in PCL and MCLsup length was concealed by the
experimental indeterminacy. An analytical model is given that provides
subject-specific plausible ligament length variations as functions of the knee
flexion angle and that can be incorporated in a multi-body optimization procedure.
CI - Copyright (c) 2011 Elsevier B.V. All rights reserved.

Langue : ANGLAIS