Article

Rescaling generic models is the most frequently applied approach in generating
biomechanical models for inverse kinematics. Nevertheless it is well known that
this procedure introduces errors in calculated gait kinematics due to: (1) errors
associated with palpation of anatomical landmarks, (2) inaccuracies in the
definition of joint coordinate systems. Based on magnetic resonance (MR) images,
more accurate, subject-specific kinematic models can be built that are
significantly less sensitive to both error types. We studied the difference
between the two modelling techniques by quantifying differences in calculated hip
and knee joint kinematics during gait. In a clinically relevant patient group of
7 pediatric cerebral palsy (CP) subjects with increased femoral anteversion, gait
kinematic were calculated using (1) rescaled generic kinematic models and (2)
subject-specific MR-based models. In addition, both sets of kinematics were
compared to those obtained using the standard clinical data processing workflow.
Inverse kinematics, calculated using rescaled generic models or the standard
clinical workflow, differed largely compared to kinematics calculated using
subject-specific MR-based kinematic models. The kinematic differences were most
pronounced in the sagittal and transverse planes (hip and knee flexion, hip
rotation). This study shows that MR-based kinematic models improve the
reliability of gait kinematics, compared to generic models based on normal
subjects. This is the case especially in CP subjects where bony deformations may
alter the relative configuration of joint coordinate systems. Whilst high cost
impedes the implementation of this modeling technique, our results demonstrate
that efforts should be made to improve the level of subject-specific detail in
the joint axes determination.
CI - Copyright (c) 2010 Elsevier B.V. All rights reserved.

Langue : ANGLAIS