Biomedical Engineering Reference
In-Depth Information
of tracking the movements of the underlying bone by
this kind of device was assessed by comparing the
kinematics obtained from external markers fixed to this
device and that obtained by calibrated fluoroscopy for flexion
up to 65° [SAT 96]. The mean error was 0.4° in varus-
valgus, 2.3° in axial rotation and 2.4 mm in anteroposterior
translation.
Postural and functional calibration (described later) were
developed to define, using this device, the anatomical axes on
which the kinematic parameters are calculated. Many
studies have been carried out to verify the reproducibility of
rotations and translations of the knee assessed in this way.
Hagemeister
et al.
[HAG 05] reported a mean error in
repeatability less than 0.8° for all rotations and 2.2 mm for
anteroposterior translation (0.4° and 0.8 mm respectively,
interoperator) for 15 subjects and 3 operators. A second
study [LAB 08] also verifies the reproducibility when the
device is systematically repositioned on the subject before
taking new measurements on 15 subjects and 3 operators. In
this case, the intra-class correlation coefficients vary
between 0.88 and 0.94. Due to these good results, associated
with high clinical potential of an objective assessment of
knee kinematics in motion [LUS 12], this device was
marketed under the name KneeKG™.
The study presented in this section aims to describe the
three-dimensional modifications of knee kinematics during
gait in patients suffering from gonarthrosis, using the
system KneeKG™. It synthesizes part of the work in the
Ph.D. thesis of D. Bytyqi [BYT 14].
5.4.1.
Materials and methods
Gonarthrosis, or arthrosis of the knee, is the most
common cause of knee pain after the age of 50. It
