Four radiological measures to estimate shoulder balance in scoliosis

We studied four indirect radiological measures of shoulder balance, their correlation with true shoulder balance, and measurement error of each method. Thirty-three consecutive patients with idiopathic scoliosis requiring surgical treatment were selected. Actual shoulder level was determined from a line in the top margin of the acromion clearly visualized in the wide chart. Indirect references used to assess shoulder balance were tilting of cephalic end-plate of T1, inclination of a line through superior border of both first ribs, the level of top margin of coracoid processes, and the level of two specific points where the clavicle intersects the rib cage. All radiographs were assessed by three independent observers. Correlation coefficients between each measurement and true shoulder level were 0.54 for T1 tilting (p = 0.001), 0.63 for first rib inclination (p < 0.001), 0.96 for coracoid process (p = 0.0001), and 0.93 for clavicle-rib cage intersection (p = 0.0001).