The typical steps  of the Delphi method  were performed. After the topic of the consensus was defined, the group of experts in scoliosis treatment comprising SOSORT members was constructed, based on the professionals participating to previous consensus procedures. The first questionnaire was prepared, checked by the authors and distributed via e-mails among the SOSORT Board Members. The responses were analyzed and the Pre-Meeting Questionnaire (PMQ) was created (Additional File 1), then distributed electronically among the participants. The answers to PMQ were collected and analyzed, then the Meeting Questionnaire (MQ) was prepared (Additional File 2). During the SOSORT Annual Meeting the Consensus Session was organized, chaired by the first author (T.K.). Each item of the MQ was illustrated with PowerPoint presentation prepared by the Chairman, moreover participants could make short presentations concerning the particular items under discussion. The answers to the MQ were collected and statistically treated.
The development and refinement of the questionnaire aimed to select the domains of primary importance for patient evaluation. The final questionnaire (MQ) consisted of five section: (1) general, (2) clinical examination, (3) radiological examination, (4) surface topography examination, (5) respondent's demographic data. The clinical examination comprised seven domains composed of 36 items (numbers of items in brackets): anthropometry (10 items), maturation (3), lower limbs discrepancy (4), trunk balance (3), sagittal plane (1), rib prominence (9), aesthetics (6). The radiological examination comprised twelve domains (79 items): patient positioning (12 items), cassette size (3), views (11), radiation protection (5), frontal plane parameters (6), rotation assessment (7), sagittal plane parameters (7), bone age (3), logistics (5), schedule (16), in-brace radiograph (2), follow-up (3). Surface topography examination comprised nine domains (72 items): hardware (5 items), patient positioning (5), views (3), logistics (13), anatomic landmarks (10), general and frontal plane parameters (17), sagittal plane parameters (8), transverse plane parameters (8) and pelvis (3). The final questionnaire is available as Additional File 2.
Questions were constructed to collect the participants' opinion on the usefulness of each particular parameter. The possible answers were as follows: 3 - always recommended; 2 - I use and recommend to use when it's needed; 1 - I don't use but it could be useful; 0 - never and I think it's not useful. In the Results section of this paper the score is presented as follows: Highest priority (3), Recommended (2), Acceptable (1) or Not recommended (0). Comments and complementary information could be freely provided at the end of each section. Each question was analyzed for agreement. The agreement for recommendation to use a particular parameter was calculated as the sum of the percentage of answers "always recommended (3)" and "I use and recommend to use when needed (2)" to the total number of participants who answered the question. SOSORT Scoliosis Evaluation Form was constructed with all items that received 75% of agreement or more and did not received more than 10% of "not recommended" answers while items that received 90% agreement or more were bolded as recommended for systematic use. SOSORT Scoliosis Evaluation Form is presented in Additional File 3.