With this paper we aimed to develop a routine clinical tool for aesthetic evaluation of scoliosis patients, evolving from our yearly experience in grading some parameters (shoulders, scapulae, waist).
The goal was to verify the intra- and inter-rater repeatability, but most of all the sensitivity to change in a clinical setting. A secondary aim was to build on our experience to develop a new tool to be studied. Our first evaluation showed an overall fair repeatability for AI. Buchanan et al.  found a similar reliability for the intra- and inter-observer cosmetic deformity rating among a group of orthopaedic surgeons. However, the present study revealed a low sensitivity of AI to changes; indeed, a three-point change out of seven is the minimum change that could be considered significant. This limits the application of the AI to the detection of major changes. Therefore, we broadened all applicable parameters, determined through our experience to be easily detectable, and developed TRACE. While maintaining the same fair intra-rater repeatability, a higher sensitivity to changes is the main feature of TRACE. In fact, the 95% level of agreement remained similar (2 points both for AI and TRACE for intra-rater) but the scale was now of 12 instead of 7 points (almost double that of AI): A score of three points out of twelve represents a significant change during treatment when the observer is the same. This makes TRACE much more useful than AI, since it makes it possible to objectively monitor the aesthetic effects of treatment. Both AI and TRACE have been used as research tools, and we documented that TRACE is sensitive enough to detect changes induced by a brace treatment [18–20]. Moreover, this is a "no-cost" tool that can be used easily and quickly during each clinical assessment. It requires neither expensive instruments nor prolonged evaluation sessions. Usually it is sufficient to mark the sub-scale values and calculate the total TRACE score, such that in routine clinical practice photographic comparison is not needed (as we usually do since 5 years with our ISICO database software) [19, 21–23].
Trunk deformity significantly influences AIS patients' perception of function and self-image . Therefore, both rehabilitation experts and surgeons emphasise this aspect in the decision-making process in AIS [1, 2, 25]. To date, the main outcome measures concerning the aesthetic effects of treatment are related to prominence changes  and the improvement of vertebral rotation  after brace treatment, to reduced Cobb angle after surgery [28, 29], or the improvement in self-perception of the deformity as assessed by questionnaire. Some attempts to quantify aesthetic deformity with a clinical assessment have been performed: Theologis proposed a "Cosmetic Spinal Score (CSS)," according to which ten non-medical judges evaluated colour pictures of AIS patients . The limit of this evaluation is that it gives a score pertaining to a general impression of the patient's back but is not based on precisely defined sub-scores. Nevertheless, CSS was shown to be related principally to rib hump and trunk side shift. Moreover, we have no data concerning its reliability when performed by expert physicians.
The principle that scoliosis is not simply a curvature indicated through x-ray imaging and that there is a need for appropriate outcome measures to supplement Cobb angle has been widely recognized [1, 25]. TRACE provides a semi-quantitative scale for clinical assessment of deformity in AIS, based on specifically defined sub-scales. Knowing the limits and the repeatability of this scale will give clinicians more reliability in the routine clinical assessment of deformity, and will provide other sensitive outcome measures. TRACE is consistent with this need, and it can readily be used in the clinical evaluation of AIS patients and for research.
One limitation of this study was the use of pictures instead of an immediate evaluation of patients. Nevertheless, evaluation through pictures has been the standard applied in previous studies,[2, 4, 5] and we can presume the repeatability to be even greater during routine clinical practice due to the opportunity for a three-dimensional evaluation of the patient. In fact, photographs are static while a three-dimensional clinical assessment presumably can be more consistently recorded by the physician, and in future studies can provide a tool to compare TRACE with the POTSI index. Another limit could be the low Kappa Statistics values obtained, even if comparable to those obtained by others evaluating aesthetics previously; but is less important for clinical routine use than the minimum significant change.
This study documents the evolution of TRACE from AI. TRACE is sufficiently repeatable and sensible for routine clinical practice, and therefore comprises is a no-cost tool designed for the conservative clinical setting.