## 4 Discussion
With the system we propose, we would measure at least the two most-twisted vertebrae, at the apex of the scoliotic curve (in case of doubt, three should be measured), and use the value of the vertebra with the highest degree of twisting, whereby the software would then calculate the degree of torsion automatically, after determining the four reference points that are used for this method. We used an improved version of the Raimondi method for measuring AVR ([PERSON] et al., 2010; [PERSON] et al., 2009; [PERSON], 1995) using software that implements it (TraumaMeter v. 873). This software has been validated and allows for the AVR to be measured more accurately than by the traditional manual measurement method, with Raimondi tables on plain radiographs (with a validity and reliability of 0.53\({}^{\circ}\)\(\pm\) 1.9\({}^{\circ}\), the mean ICC (2.1) of the measurements being ICC = 0.913 with a 95% confidence interval = 0.87-0.949). The differences found between AVR measurements on the two types of vertebrae may be due to the overlap of the ribs and costovertebral joints that make it difficult to establish the limit of the width of the vertebral body and the smaller size of the thoracic vertebrae when compared to the lumbar vertebrae. Regarding terminology, the term _rotation_ is commonly a synonym for _torsion_ in the medical literature. We consider that _rotation_ is the physiological mobility of the vertebrae relative to each other in the axial plane, and _torsion_ is a pathological deformity of a vertebra with a fixed rotation position in the axial plane [5]. We think it would be correct to use the term _axial vertebral torsion_ (AVT), but we have used the term _axial vertebral rotation_ (AVR) in the present article, because it is the most common in the literature. Inaccuracy in AVR measurements may influence the diagnosis of scoliosis severity. The authors suggest that the evaluation of AVR using Traumameter v. 873, as an improved and digital version of [PERSON]'s method, would be helpful in clinical practice to increase the accuracy of AVR measurements, despite the significant inaccuracy in the determination of thoracic AVR when compared to lumbar AVR. Our study had some limitations. Firstly, we did not consider the computer equipment of each tester (e.g., visible image size, screen resolution, luminance, contrast ratio, mouse, or touchpad characteristics) that may have somewhat influenced the accuracy of the measurements. Secondly, we removed the outliers from some of the study distributions (due to imperfect measurements or errors in recording the values of the measurements in the database provided by each observer, or the incorrect selection of the most rotated vertebra). On the other hand, we think that the experience level of the evaluators is not a limitation, since the intra-group and inter-group agreement of the measurements with the software shows equal or minor variations than those of the manual method, among the different measurement sessions and independently of the experience level. Despite these limitations, the authors consider the results of the study to be valuable, as there are no published studies, to our knowledge, on the \"absolute reliability\" of measurements that have been made on different types of vertebrae, or by using a more accurate and precise measuring instrument than those traditionally used.