Test-retest reliability of upper limb robotic exoskeleton assessments in children and youths with brain lesions

Abstract

In children with congenital or acquired brain lesions, impaired upper limb function can affect independence. Assessing upper limb function is important for planning and evaluating neurorehabilitative interventions. Robotic devices increase measurement-objectivity and enable measuring parameters reflecting more complex motor functions. We investigated the relative and absolute test-retest reliability of assessments to measure upper limb functions in children and adolescents with brain lesions with the exoskeleton ChARMin. Thirty children (9 females, mean age ± SD = 12.5 ± 3.3 years) with congenital brain injuries (n = 15), acquired (n = 14), both (n = 1) and impaired upper limb function participated. They performed the following ChARMin assessments and repeated them within three to seven days: active and passive Range of Motion (ROM), Strength, Resistance to Passive Movement, Quality of Movement, Circle, and Workspace. We calculated the systematic difference, Intraclass Correlation Coefficient (ICC) and Smallest Real Difference (SRD) for each parameter. Six parameters of three assessments showed systematic errors. ICCs ranged from little to very high and SRD values varied considerably. Test-retest reliability and measurement errors ranged widely between the assessments. Systematic differences indicated that random day-to-day variability in performance would be responsible for reduced reliability of those parameters. While it remains debatable whether robot-derived outcomes should replace certain routine assessments (e.g., ROM, strength), we recommend applying certain technology-based assessments also in clinical practice.Trial registration: This study was registered prospectively at ClinicalTrials.gov (identifier: NCT02443857) on May 14, 2015.

Conflict of interest statement

The authors declare no competing interests.

© 2022. The Author(s).

Figures

Figure 1

Schematic picture of the ChARMin robot. (A) The small distale module (B) The large distal module. Courtesy of Susanne Staubli and Urs Keller.

Figure 2

Interfaces of the assessments. (A) Active and passive Range of Motion. (B) Isometric Strength. (C) Resistance to Passive Movement. (D) Quality of Movement: eight targets appearing radially around the centre point need to be reached. After each target, the participant has to return to the centre position. (E) Circle following: the green ball moves in a circle and the participant is instructed to position the red ball as exactly as possible on the green ball throughout the circular movement. (F) Workspace: the participant is instructed to make the virtual room on the screen as large as possible by pushing with the red block against each wall (in forward, backward, left and right direction, respectively), the ceiling upwards and the floor downwards. The block represents the position of the wrist and is steered by moving the arm in the according direction.

Figure 3

Data distribution of the parameters with the highest and the lowest intraclass correlation coefficients (ICC). (A) The parameter ‘maximum distance to front’ of the Workspace assessment which showed the highest ICC (= 0.95). (B) The parameter ‘resistance against shoulder external rotation’ of the Resistance to Passive Movement assessment (RPM) which showed the lowest ICC (= − 0.03).

Figure 4

Measurement errors. The box-plots represent the distribution of the smallest real differences as a ratio of the grand means of all the parameters of each assessment. (A) Active Range of Motion (aROM), passive Range of Motion (pROM), Strength, Quality of Movement (QoM), Circle, and Workspace assessments. (B) Resistance against passive movement (RPM).

Figure 5

Examples of trajectories of Quality of Movement and Circle assessmentsThe trajectories were obtained from data of an adolescent participant with acquired hemiparesis and a MACS level III who had difficulties in moving the arm upwards against gravity. (A) Quality of Movement assessment: Paths for the movements from the targets to the centre point. Upper targets were not reached. (B) Circle assessment: Paths of the three rounds of tracking the ball moving in a circle. The upper part of the circle was not reached. Red line = round one, green line = round two, blue line = round three. The excursion of the movement becomes smaller with each round.