Biomedical Engineering Reference
In-Depth Information
[
83
] revealed that the intrinsic stiffness has a little change when compared to the
ankle moment, despite a large change in muscle activation. It is unlikely that the
muscle stiffness is the source of joint stiffness, but the aponeurosis, tendon and bone
architecture of the foot. So in the standing position the stiffness is not on neural
control, but is a biomechanic constant. Thus, increased the idea that the stiffness
increases when the ankle movements are smaller and slower [
83
]. However, when
there is an angular displacement during walking, we noticed a stiffness in the joint,
which was called dynamic stiffness [
84
].
As expressed in the introduction, the postural stability evaluation is often made
by clinical tests such as the Berg Balance Scale [
19
]. However, these instruments
often fail to detect minimal changes in postural stability in patients who have
not shown functional changes. An evaluation that can detect small perturbations
before the functional changes, allows early intervention, prevents deterioration and
functional limitation.
3
Methodology
3.1
Objectives
The purpose of this study was to characterize the center of pressure behaviour in the
standing position and in the stance phase of gait (1-step protocol) in subjects with
multiple sclerosis. Based on previous studies [
12
,
57
,
85
,
86
] the present study used
five COP parameters sensitive to postural balance and MS postural changes: Medial-
lateral COP displacement (ML); Anterior-posterior COP displacement (AP); Total
COP displacement (TD); Ellipse area (EA) and Total Contac Time (CT). Were also
tried to establish relations between the results obtained in COP evaluation and scores
obtained in Berg Balance Scale
3.2
Subjects
The study was conducted with support from Portuguese Society of Multiple
Sclerosis. Inclusion criteria for participation were: (1) clinical diagnosis of MS,
conducted by a neurologist; (2) aged between 18 and 65; (3) ability to maintained
upright standing position for 60 s; (4) ability to perform the 1-step protocol.
Exclusion criteria were: (1) other neurological conditions such stroke or brain
trauma; (2) cardiovascular diseases or other causes that interfere with the imple-
mentation of the evaluation protocol; (3) cognitive deficits; (4) included in another
study of MS. To verify the inclusion criteria, a questionnaire was sent by email,
to each subject with MS, who intended to participate. Before test procedures, each
subject performed an interview to collect demographic, anthropometric and clinical
