Test-Retest repeatability of gluteus maximus strength testing using a fixed digital dynamometer in children with cerebral palsy.

Abstract

To investigate the test-retest repeatability of the measurement of the gluteus maximus strength using a fixed digital dynamometer. Test-retest design. The strength of the gluteus maximus was measured in prone position during 2 sessions an average of 6 days apart. Gait analysis laboratory. Eleven children with spastic diplegic (n=10) and hemiplegic (n=1) cerebral palsy (CP), age 6 to 14 years, and 11 aged-matched children. All were able to walk independently, but 2 in the CP group used walking aids. Not applicable. On 2 occasions, gluteus maximus strength was measured 3 times in 2 positions of the hip joint. Repeatability of the measurements was assessed by intraclass correlation coefficients (ICCs), coefficients of variation, and the coefficient of repeatability. When normalized to body mass, children with CP had significantly less gluteus maximus strength compared with the controls. The ICCs for the control group ranged from .76 to .85 and from .75 to .83 for the involved leg in the CP group. The reliability of measurement of gluteus maximus strength was good for both control group and the involved leg of the CP group. The normalized values for gluteus maximus strength and measures of reproducibility can be used when measuring gluteus maximus strength in children with CP.