Measurement of muscle stiffness using robotic assisted gait orthosis in children with cerebral palsy: a proof of concept.
OBJECTIVE
To evaluate the feasibility and reliability of a novel stiffness assessment tool implemented in the driven gait orthosis Paediatric Lokomat; to investigate the influence of single robotic-assisted gait training (RAGT) on muscle stiffness in children with cerebral palsy (CP).


METHODS
Ten children with spastic CP conducted a single standard RAGT session and stiffness was assessed before and after the RAGT. Nine of the ten subjects were tested twice on the same day to investigate test-retest reliability, intraclass correlation coefficients (ICCs), standard error of measurement (SEM), coefficient of variation of the method error (CV(ME)) and resistive torques during passive leg movements (stiffness in Nm/°) were calculated.


RESULTS
ICCs showed high reliability (0.83-0.97) for hip and knee movements. SEM and CV(ME) indicated 0.028-0.085 Nm/°, 9.5-23.0% of test-retest variability in hip and 0.018-0.064 Nm/°, 13.3-43.5% in knee measures. Using the assessment tool, a significant decrease in muscle stiffness in participants, especially in children with high levels of muscle tone, could be shown after a single session of RAGT.


CONCLUSIONS
The assessment tool L-STIFF is a feasible tool for automated measurement of stiffness in children with CP, but it is not sensitive enough to record small changes in muscle tone.
Schmartz
Annick C
AC
Institute of Human Movement Sciences and Sport, ETH Zurich, Zurich, Switzerland.
Meyer-Heim
Andreas D
AD
Müller
Roland
R
Bolliger
Marc
M
D001696:Biomechanical Phenomena; D001837:Body Weights and Measures; D002547:Cerebral Palsy / Q000534:rehabilitation*; D002648:Child; D002675:Child, Preschool; D005260:Female; D005684:Gait / Q000502:physiology*; D006801:Humans; D008297:Male; D009127:Muscle Rigidity / Q000534:rehabilitation*; D009128:Muscle Spasticity / Q000534:rehabilitation; D009989:Orthotic Devices; D026741:Physical Therapy Modalities; D015203:Reproducibility of Results; D012371:Robotics