Therapy modifies end-vertebrae, and measuring always on the same vertebrae overestimates final results. A blind cohort controlled prospective study

Background By definition, Cobb angle is formed by the lines parallel to the superior end-plate of the superior end-vertebra (EV) and the inferior end-plate of the inferior EV, where EVs are the most tilted vertebrae. Evaluating idiopathic scoliosis (IS) results of treatment, some experts measure in different x-rays the EVs obtained at start-of-treatment (SOT); others change EVs in each single x-ray. In literature, no work ever verified if there is a difference between the two methods, nor if any agreement exists on what should be done.