The Intra- and Inter-Rater Reliability of an Instrumented Spasticity Assessment in Children with Cerebral Palsy

Abstract

AimDespite the impact of spasticity, there is a lack of objective, clinically reliable and valid tools for its assessment. This study aims to evaluate the reliability of various performance- and spasticity-related parameters collected with a manually controlled instrumented spasticity assessment in four lower limb muscles in children with cerebral palsy (CP).MethodThe lateral gastrocnemius, medial hamstrings, rectus femoris and hip adductors of 12 children with spastic CP (12.8 years, ±4.13 years, bilateral/unilateral involvement n=7/5) were passively stretched in the sagittal plane at incremental velocities. Muscle activity, joint motion, and torque were synchronously recorded using electromyography, inertial sensors, and a force/torque load-cell. Reliability was assessed on three levels: (1) intra- and (2) inter-rater within session, and (3) intra-rater between session.ResultsParameters were found to be reliable in all three analyses, with 90% containing intra-class correlation coefficients >0.6, and 70% of standard error of measurement values <20% of the mean values. The most reliable analysis was intra-rater within session, followed by intra-rater between session, and then inter-rater within session. The Adds evaluation had a slightly lower level of reliability than that of the other muscles.ConclusionsLimited intrinsic/extrinsic errors were introduced by repeated stretch repetitions. The parameters were more reliable when the same rater, rather than different raters performed the evaluation. Standardisation and training should be further improved to reduce extrinsic error when different raters perform the measurement. Errors were also muscle specific, or related to the measurement set-up. They need to be accounted for, in particular when assessing pre-post interventions or longitudinal follow-up. The parameters of the instrumented spasticity assessment demonstrate a wide range of applications for both research and clinical environments in the quantification of spasticity.

Medial gastrocnemius muscle stiffness cannot explain the increased ankle joint range of motion following passive stretching in children with cerebral palsy

“…The calculation of net ankle joint moment is described in Figure 1 ( Bar-On et al, 2013;Schless et al, 2015). A modified semi-automated tracking software package (Cronin, Carty, Barrett, & Lichtwark, 2011;Gillett, Barrett, & Lichtwark, 2013)…”

“…M orthosis is the predicted moment caused by gravity on the orthosis. The joint moment is given by: M ankle = − F z d z − F y d y − M x − M orthosis (Bar‐On et al., ; Schless et al., )…”

“…Anatomical calibration of the shank and foot reference frames was applied to obtain the ankle angle (Leardini et al., ). The calculation of net ankle joint moment is described in Figure (Bar‐On et al., ; Schless et al., ). A modified semi‐automated tracking software package (Cronin, Carty, Barrett, & Lichtwark, ; Gillett, Barrett, & Lichtwark, ) was used to track the fascicles and aponeuroses.…”

“…M orthosis is the predicted moment caused by gravity on the orthosis. The joint moment is given by: Schless et al, 2015) and within 10 min after the stretching session, measurements of ankle angle, passive joint torque and medial gastrocnemius muscle fascicle lengthening during a passive stretch were taken. During these measurements, participants lay prone on a bed with the lower leg supported on an inclined cushion such that the knee was ∼20 deg attached to the orthosis under the ball of the foot.…”

Muscle and tendon lengthening behaviour of the medial gastrocnemius during ankle joint rotation in children with cerebral palsy

“…The axis of rotation of the orthosis was aligned with the lateral malleolus.The foot was secured to a rigid footplate with the help of an adjustable insole that ensured contact of the heel with the footplate during ankle rotation. The reliability of data measured using the same equipment has been reported previously(Schless et al, 2015). Each participant underwent two trials involving three passive movements by manually rotating the foot from maximal plantarflexion to maximal dorsiflexion, aiming for a maximal angular velocity of 15 ± 5 deg s −1 , which is slow enough to not elicit a stretch reflex (Bar-On et al, 2013) and ≥10 s rest in between individual repetitions (Bar-On et al, 2013).…”