Reliability of maximum isometric hip and knee torque measurements in children with cerebral palsy using a paediatric exoskeleton – Lokomat

Abstract

The Lokomat (by L-Force tool) allows the measurement of the maximum voluntary isometric torque (MVIT) at the knee and hip joints in a standing position, as close as possible to the posture adopted during walking. However, the reliability of this measurement in children with cerebral palsy (CP) remains unknown. The main goal of this study was to evaluate inter and intra-tester reliability of a novel tool (L-Force) in CP population. L-Force reliability was determined in 17 children with CP by two experienced therapists. We collected MVITs in hip and knee flexors and extensors. Relative and absolute reliability of maximum joint torques were estimated using the intra-class correlation coefficient (ICC) and standard error of measurement (SEM), respectively. The correlation between L-Force and hand-held dynamometer (HHD) was also reported. ICCs were good to excellent for intra and inter-tester reliability (all P≤0.001). The SEM ranged from 2.0 to 4.1 Nm (12.1 to 21.7%) within-tester and from 2.1 to 3.5 Nm (11.9 to 22.5%) between testers. The correlation was fair to good between L-Force and HHD measures (r=[0.50-0.75]; all P˂0.01) with higher values for flexors than extensors. The L-Force is a reliable tool for quantifying the hip and knee flexors and extensors torques in children with cerebral palsy with an important timesaving and in a more functional posture than traditional HHD.