1st Joint ESMAC-GCMAS Meeting - Análise de Marcha

- 110 -
O-28
NORMALCY GAIT INDEX AND KINEMATICS: UNCERTAINTY AND
REPEATABILITY ON HEALTHY CHILDREN DATABASE. PRELIMINARY
APPLICATION ON CEREBRAL PALSY GROUP.
Assi, Ayman, PhD student 1,2 , Ghanem, Ismat, Surgeon 2,3 , Laassel, El Mostafa, PhD 5 ,
Penneçot, Georges-François, Surgeon 4 , Lavaste, François, PhD 1 , Skalli, Wafa, PhD 1
1 Laboratoire de Biomécanique ENSAM CNRS UMR 8005, Paris, France
2 Gait & Motion Analysis lab. SESOBEL, Aintoura, Lebanon
3 Hôpital Hôtel-Dieu de France, Beirut, Lebanon
4 Hôpital Robert Debré, Paris, France
5 CRF Bois-Larris, Lamorlaye, France
Summary/conclusions
A large database of asymptomatic gait children was established. Repeatability and uncertainty
of normalcy gait index and kinematics using Helen Hayes protocol were evaluated. This study
should allow more relevant comparison between patients and healthy children, and between pre
and post treatments.
Introduction
Most of Cerebral Palsy studies use Helen Hayes protocol [1] to calculate kinematics
parameters. Recently, Normalcy Gait Index [2] was proposed to estimate deviation of a
subject’s gait from a normal profile. This index shows potential as a useful tool to objectively
quantify overall changes in patient’s gait.
Statement of clinical significance
Repeatability of normalcy gait index has not been evaluated yet, and repeatability of Helen
Hayes protocol was primarily evaluated for adults [3]. As the technique and associated
parameters become the basis of gait quantitative evaluation, it is important to estimate their
uncertainty to help in clinical interpretation. The aim of this study is to evaluate uncertainty
and repeatability of kinematics parameters and normalcy gait index, and to constitute a
database of healthy children. A preliminary clinical application was performed on a small
group of cerebral palsy children.
Methods
56 asymptomatic children (28 boys, 28 girls) aged between 5 and 15 years old (mean: 10) have
performed the gait exam (VICON ® system MX3) using the Helen Hayes protocol. 29
kinematic parameters [4] were extracted from lower limb joint angles curves. Normalcy gait
index (NI), using the same parameters as Shutte et al. [2], was also calculated on this database.
16 subjects performed the exam twice with markers replacement to assess repeatability of
parameters. Uncertainty was assessed as 2SD of differences to mean values between the 2
sessions. A preliminary clinical application was performed on 8 cerebral palsy children (mean
age: 9 years old). 3 patients were quadriplegics, and 5 were diplegics. Different trials were
collected when patient was used to use one of these assistances during his walk: key-walker,
orthosis, canes and shoes. A simple gait is acquired when patient can walk without technical
assistance. As trials could not be repeated for patients, Monte Carlo simulations were carried
out by adding a noise measurement on each kinematic curve used in NI computation, to
evaluate its uncertainty. These simulations were done on asymptomatic and cerebral palsy
subjects. 2SD values of uncertainty are presented.
Results
A database of healthy subjects with “corridors” of normality was established for kinematics
and kinetics curves. NI calculated within asymptomatic children ranged between 5 and 30, with