Validity and reliability of photographic measures to evaluate waistline asymmetry in idiopathic scoliosis

Abstract

Evaluate the relationship between radiological, clinical and perceived waistline asymmetry (WLA) in a sample of idiopathic scoliosis (IS) patients. 77 patients were included (mean age 20.3years; 85% women). We obtained a full X-ray of the spine and back clinical photography for all patients. On photographs, waist height angle (WHA), right/left waist angles (WA) and right/left waistline distance ratio were measured. SRS22, Trunk Appearance Perception Scale (TAPS) and Spinal Appearance Questinnaire (SAQ) questionnaires were also completed. The intra and inter-observer reliability of each photographic measure was assessed. A correlation analysis between all variables was done using Pearson Correlations Coefficient. All measures reported have excellent intra- and inter-observer (ICC ≥0.8) reliability. A significant correlation was found between WHA and Cobb angle, mainly with Main Thoracic (MT) (r=-0.56). Right and left waist angles, and especially the difference between them (RLWAD), is related to the thoracolumbar/lumbar (TLL) curve. We have found a significant correlation between RLWAD and TLL curve magnitude (r=-0.54) and with the inclination of the lower end vertebra (LEV) (r=0.74). Only WHA has a significant, but poor correlation (r≅0.3) with trunk perception scales (TAPS and SAQ). No other significant correlations were found between WLA measures and patient related outcome scores. WLA measures proposed in this article are reliable tools to assess WLA. We have found a significant correlation between clinical WLA and skeletal deformity (Cobb angle). WHA is related with MT curve while the RLWAD depends on the TLL curve magnitude and its LEV. We have also found a significant relation between WHA and the patient's perception of the deformity. It seems that WLA is a cosmetic concern to take into account in clinical evaluation of IS patients.