Trunk imbalance in adolescent idiopathic scoliosis.

BACKGROUND CONTEXT: Trunk imbalance (ie, frontal trunk shift measured with a plumb line from C7 to S1) is part of the clinical evaluation in adolescent idiopathic scoliosis (AIS), but its prevalence and relationship with scoliosis, back pain, and health-related factors are not well documented. PURPOSES: The principal objectives are to document trunk imbalance prevalence and to explore the association between trunk imbalance and the following factors: Cobb angle, type of scoliosis, back pain, function, mental health, and self-image. The secondary objective is to determine back pain prevalence and the relationship between back pain and each of the following: Cobb angle, function, mental health, and self-image. STUDY DESIGN/SETTING: This is a cross-sectional study in a scoliosis clinic of a tertiary university hospital center. PATIENT SAMPLE: The sample includes youth with AIS (N=55). OUTCOME MEASURES: The outcome measures were trunk imbalance prevalence and magnitude, and back pain prevalence and intensity using the Numeric Pain Rating Scale (NPRS) and the Scoliosis Research Society-22 (SRS-22) pain score, and the function, self-image, and mental health domains of the SRS-22. METHODS: Trunk imbalance and back pain were assessed in 55 patients with AIS (Cobb angle: 10-60°). Patients completed the SRS-22 questionnaire and the NPRS. Correlations were done between trunk imbalance and scoliosis (Cobb angle, type of scoliosis), back pain (NPRS and SRS-22 pain score), and health-related factors using Pearson correlation coefficients (r) and logistic regression models. RESULTS: Trunk imbalance prevalence is 85% and back pain prevalence is 73%. We found fair to moderate significant positive correlation between trunk imbalance and Cobb angle (r=0.32-0.66, p<.05) but not with back pain, function, mental health, self-image, or type of scoliosis. Lower self-reported pain significantly correlated with lower Cobb angles (r=0.29, p=.03), higher function (r=0.55, p=.000), higher self-image (r=0.44, p=.001), and better mental health (r=0.48, p=.000). There was a trend for trunk imbalance to be related with lower pain in logistic regression models. CONCLUSIONS: The high prevalence of trunk imbalance in AIS highlights the importance of screening for this clinical sign in growing adolescents. Further research should be done with regard to the treatment of trunk imbalance and its implication on both Cobb angle and back pain.

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

STUDY DESIGN: Reliability-validity study. OBJECTIVES: The 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 DATA: Measurement 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. METHODS: Trunk 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. RESULTS: Plumbline 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. CONCLUSIONS: The measurement of trunk list using the plumbline or via photograph is both reliable and valid for both foot positions.