# RELIABILITY OF UPPER LIMB KINEMATIC VARIABLES: ADULTS WITH UNILATERAL CEREBRAL PALSY PERFORMING A STANDARDIZED DRINKING TASK

## TL;DR

This study shows that motion capture systems reliably measure upper limb movements in adults with cerebral palsy during a drinking task.

## Contribution

The study confirms the reliability of optical motion capture for assessing upper limb function in adults with unilateral cerebral palsy.

## Key findings

- All kinematic variables showed excellent test–retest reliability (ICC 0.90–0.99).
- Agreement metrics were within small ranges for elbow, shoulder, and trunk movements.
- The method is suitable for evaluating treatment effects and tracking upper limb function over time.

## Abstract

To evaluate the test–retest reliability and agreement of kinematic variables measured with an optical motion capture system during a standardized drinking task in adults with unilateral cerebral palsy (CP).

Test–retest.

25 subjects (12 males) with spastic unilateral CP, aged 18–60 years.

Kinematic variables were collected while participants performed a drinking task with the affected upper limb on 2 consecutive days. Inter-session reliability and agreement were estimated using the intra-class correlation coefficient (ICC) 2.1, and standard error of measurement (SEM).

Reliability was excellent for all investigated variables (ICCs: 0.90–0.99). Agreement for elbow flexion/extension, shoulder flexion, and abduction: SEM ≤ 3.1 degrees, max trunk displacement during reaching: SEM = 9.9 mm, number of stops/starts during total movement: SEM = 2.1 movement units, total movement time: SEM = 1.0 s.

Optical motion capture of a standardized drinking task was reliable for evaluating upper limb movements in adults with spastic unilateral CP. The method may be used as an outcome measure to evaluate the effect of treatments of upper limb function, as well as to follow the function over time.

Adults with cerebral palsy (CP) experience problems with reaching, grasping, and releasing objects due to decreased motor control. Specialized camera systems, which are now clinically available, could be a step forward in objective assessment of upper limb function in neurological populations. The main aim of this study was therefore to evaluate the consistency of motion variables obtained during a drinking task using a motion-capture system. Twenty-five adults with CP were measured on 2 occasions while performing this task. The results showed a high level of consistency between the 2 measurements for all investigated motion variables. We therefore concluded that the method may be used as an outcome measure to evaluate the effect of treatments of upper limb function, as well as to follow the function over time.