1st Joint ESMAC-GCMAS Meeting - Análise de Marcha

O-11
A SINGLE GAIT CYCLE AS MEASURED BY FOUR CURRENT PROTOCOLS
Ferrari, Alberto, MEng 1 , Pavan, Esteban, PhD 2 , Benedetti, Maria Grazia, MD 1 , Bettinelli,
Dario, MEng 3 , Frigo, Carlo, PhD 2 , Leardini, Alberto, DPhil 1
1 Movement Analysis Laboratory – Istituti Ortopedici Rizzoli, Bologna, Italy
2 Movement Biomechanics & Motor Control Lab, Bioengineering Dep., Politecnico Milano
3 Aurion s.r.l., Milano, Italy
Summary/conclusions
A single gait cycle from a volunteer was analysed simultaneously by using four different
protocols among the most commonly utilised in clinical gait analysis laboratories. The markerset
was designed to integrate those of the four relevant instructions. One volunteer was
analysed, with marker placement and necessary measurements performed by relevant experts.
Except biases associated to the different definitions of anatomical reference systems, the
consistency among the four data set obtained was considerable.
Introduction
The large number of gait analysis laboratories all over the world routinely utilise data
collection and reduction procedures embraced in a few well known protocols [1-5]. These
differ considerably for the marker-set utilised, additional measurements taken at data
collection, definition of the anatomical landmarks and references, joint axis conventions etc.
Single cases or general studies are discussed with their clinical implications and shared at
meetings and in journals indifferently coming from these disparate protocols without full
consciousness of these methodological differences. In the present study, a comparison is made
between four of these protocols by looking at exactly the same single gait cycle.
Statement of clinical significance
Gait analysis results are interpreted routinely within the process of clinical decision making,
but it is still unknown to what extent the different protocols utilised worldwide compare to
each other. This knowledge would make gait analyser more conscious about the reliability and
the limits of his own clinical gait variables.
Methods
The Plug-in-gait (Vicon Motion Systems Ltd, Oxford, UK) [1,2], Saflo [3], CAST [4] and
T3Dg [5] protocols were analysed. A single comprehensive marker-set was defined by
integrating all the four marker-sets. This resulted in 59 markers: 22 in each leg, 5 in pelvis and
10 in trunk. One subject (male, 24 years, 188 cm, 74 Kg) was instrumented accordingly and
was asked to walk barefoot at his normal speed. Necessary anthropometric measurements were
performed by examiners skilled with these protocols. Marker trajectories and ground reaction
force were collected respectively by an eight-camera Vicon 612 system and by two force plates
(Kistler Instrument AG, Switzerland) at 100 Hz. A single representative trial including the
right and left gait cycle was identified. Marker labelling and data processing including filtering
were performed independently by the relevant experts. No normalisation or off-set removal
was allowed. Relevant results were gathered from the four processes, with a careful
comprehension of the correspondences. The variability between the protocols was determined
for each kinematic and kinetic variable across the right gait cycle. The coefficient of
correlation between variables obtained by the four protocols and the mean range of variability
(MRV) were calculated, the latter being obtained by averaging the range of values at each
sample along the gait cycle [6].
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