Assessment of Gait Symmetry and Gait Normality Using Inertial Sensors: In-Lab and In-Situ Evaluation - Biomedical Engineering Systems and Technologies - page 218

3M thod

The study was conducted in two phases. The first phase was an in-lab evaluation that
compared the proposed mobile GA system with 3D kinematic analysis. The second, was
an in-situ evaluation of the proposed system against quantitative and qualitative clini-
cal assessments of hip-replacement patients. This study was approved by the Regional
Ethics Board in Gothenburg, Sweden.

3.1 In-Lab Data Collection

The data collection took place at the clinical gait lab at Sahlgrenska University Hospital,
Gothenburg, Sweden. A group of 19 healthy volunteers participated in the study. The
average hight of the group was 172.1

± 7.6 cm; and the average weight was 71.8 ±

17.2 Kg. Seven participants were male and twelve female, averaging an age of 34 ± 13

years.
Kinematic and kinetic data were recorded with a 3D motion capture (MOCAP) sys-
tem, Qualisys MCU 240, sampling at 240Hz. A total of 15 spherical reflective markers,
of 19 mm in diameter, were placed on the sacrum, anterior superior iliac spine, lat-
eral knee-joint line, proximal to the superior border of the patella, tibial tubercle, heel,
lateral malleolus and between the second and third metatarsals [26].
Subjects were also equipped with 3 Shimmer R sensor nodes, each containing one 3-
axis accelerometer and one 3-axis gyroscope, sampling at 128Hz. One node was placed
on each outer shank, about 3cm above the lateral malleolus, Figure 1. The remaining
node was placed mid-way between the anterior superior iliac spine markers, Figure 2.
Sensors were synchronized using a beacon signal from the host computer, and the data
was stored on-board each sensor node.

Fig. 2. Waist sensor node mid-way between
the anterior superior iliac spine

Fig. 1. Shank sensor node approximately 3cm
above the lateral malleolus

The subjects' movements were simultaneously recorded with the sensor nodes and
with the Qualisys system. They were instructed to walk in 3 different ways: 1) normally
at a comfortable speed; 2) with a limp, as if injured; and 3) slowly, as if very tired. All
subjects performed three tests for each type of walk. One test of each type was then
randomly chosen for further analysis.

3.2 In-Situ Data Collection

This data collection took place at the orthopedic ward at Sahlgrenska University Hos-
pital, M olndal, Sweden. Eleven patients were included in the study. All patients had