Reliability and Validity of the Clinical Measurement of Trunk List in Children and Adolescents With Idiopathic Scoliosis

Abstract

Study DesignReliability-validity study. ObjectivesThe plumbline is commonly used to evaluate trunk list in a clinical setting. The purpose of this study was to evaluate reliability and validity of the plumbline to measure trunk list in persons with idiopathic scoliosis. Secondary objectives include evaluating effects of foot position on trunk list measurement and evaluating reliability and validity of the trunk list measurement obtained from photographs. Summary of Background DataMeasurement of trunk list is an important component of posture evaluation. The plumbline is commonly used to evaluate trunk list in a clinical setting. However, information on reliability and validity is lacking. MethodsTrunk list was measured on 55 participants with idiopathic scoliosis with plumbline and photographic methods on 2 occasions by the same evaluator. At each occasion, 2 measurements were taken with feet together (FT) and two with feet apart (FA). Trunk list was calculated on radiographs taken that day. Generalizability theory was used to estimate the reliability and standard error of measurement (SEM) for the overall, test–retest and inter-trials designs. Pearson correlation coefficients (r) were used to assess validity of trunk list compared with the radiographic method. ResultsPlumbline measurement demonstrated high test–retest reliability (FT: ϕ = .98 and SEM = 2.0–2.2 mm; FA: ϕ = .98, SEM = 2.0 mm) and high inter-trial reliability (FT: ϕ = .99, SEM = 1.2 mm; FA: ϕ = .99, SEM = 1.2 mm). The test–retest and inter-trial reliability of the photographic method was slightly lower for the 2 foot positions (ϕ = .90–.98; SEM: 2.7–5.8 mm). The plumbline and photographic methods had good correlation with the measure obtained via radiograph (plumbline: r = .79–.83; photograph: r = .75–.78) in both foot positions. ConclusionsThe measurement of trunk list using the plumbline or via photograph is both reliable and valid for both foot positions.