Ultrasound assessment of deep cervical extensors morphology and quality in populations with whiplash associated disorders: An intra- and inter-examiner reliability study

Abstract

BackgroundUltrasound imaging (US) has shown to be a reliable and valid tool for assessing muscle morphology and quality. However, most studies have focused on asymptomatic populations. ObjectiveTo investigate intra- and inter-rater reliability estimates of muscle morphology and quality of cervical multifidus (CM) and short rotators (SR) in patients with whiplash associated disorders (WAD). DesignAn intra- and inter-examiner reliability study. MethodsUS images were acquired in a blinded fashion in 34 patients (35% males) by two experienced and two novice examiners. Cross-sectional area (CSA), perimeter, mean echo-intensity (EI) and the percentage of fatty infiltration were assessed twice, one-week apart, in a randomized order. Reliability estimates (i.e., intra-class correlation coefficients –ICC–, standard error of measurement -SEM-, minimal detectable change, mean of measurements, absolute and percent errors) were calculated. ResultsIntra-examiner reliability for experienced assessors ranged from good to excellent for CM and SR (ICC3,1 = 0.888–0.975 and 0.810–0.964 respectively) and from moderate-to-good for novices (ICC3,1 = 0.708–0.790 and 0.655–0.796 respectively). The agreement between the experienced examiners was moderate to good (ICC3,2 = 0.737–0.899 and 0.728–0.899 CM and SR respectively); between novice and experienced examiners was moderate to good (ICC3,2 = 0.617–0.873 and 0.657–0.766 CM and SR respectively); and between novice examiners was moderate-to-good for CM (ICC3,2 = 0.610–0.777) and moderate for SR (ICC3,2 = 0.600–0.730). ConclusionCM and SR intra-examiner reliability was good-to-excellent for novice and experienced examiners. However, inter-examiner reliability was clinically acceptable just for experienced examiners at the C4/C5 level in WAD populations.