Last two decades witnessed great advances in the surgical treatment of idiopathic scoliosis. However, the number of studies evaluating the long-term results of these treatment methods is relatively low. During recent years, besides radiological and clinical studies, questionnaires like SRS-22 assessing subjective functional and mental status and life-quality of patients have gained importance for the evaluation of these results. In this study, surgical outcome and Turkish SRS-22 questionnaire results of 109 late-onset adolescent idiopathic scoliosis patients surgically treated with third-generation instrumentation [Texas Scottish Rite Hospital (TSRH) System] and followed for a minimum of 10 years were evaluated. The balance was analyzed clinically and radiologically by the measurement of the lateral trunk shift (LT), shift of head (SH), and shift of stable vertebra (SS). Mean age of the patients was 14.4 +/- 1.9 and mean follow-up period was 136.9 +/- 12.7 months. When all the patients were included, the preoperative mean Cobb angle of major curves in the frontal plane was 60.8+/-17.5 degrees. Major curves that were corrected by 38.7 +/- 22.1% in the bending radiograms, postoperatively achieved a correction of 64.0 +/- 15.8%. At the last follow-up visit, 10.3 degrees +/- 10.8 degrees of correction loss was recorded in major curves in the frontal plane with 50.5 +/- 23.1% final correction rate. Also, the mean postoperative and final kyphosis angles and lumbar lordosis angles were 37.7 degrees +/- 7.4 degrees, 37.0 degrees +/- 8.4 degrees, 37.5 degrees +/- 8.7 degrees, and 36.3 degrees +/- 8.5 degrees, respectively. A statistically significant correction was obtained at the sagittal plane; mean postoperative changes compared to preoperative values were 7.9 degrees and 12.9 degrees for thoracic and lumbar regions, respectively. On the other hand, normal physiological thoracic and lumbar sagittal contours were achieved in 83.5% and 67.9% of the patients, respectively. Postoperatively, a statistically significant correction was obtained in LT, SH, and SS values (P<0.05). Although, none of the patients had completely balanced curves preoperatively, in 95.4% of the patients the curves were found to be completely balanced or clinically well balanced postoperatively. This rate was maintained at the last follow-up visit. Overall, four patients (3.7%) had implant failure. Early superficial infection was observed in three (2.8%) patients. Radiologically presence of significant consolidation, absence of implant failure, and correction loss, and clinical relief of pain were considered as the proof of a posterior solid fusion mass. About ten (9.2%) patients were considered to have pseudoarthrosis: four patients with implant failure and six patients with correction loss over 15 degrees at the frontal plane. About four (3.7%) patients among the first 20 patients had neurological deficit only wake-up test was used for neurological monitoring of these patients. No neurological deficit was observed in the 89 patients for whom intraoperative neurological monitoring with SSEP and TkMMEP was performed. Overall, average scores of SRS-22 questionnaire for general self-image, function, mental status, pain, and satisfaction from treatment were 3.8 +/- 0.7, 3.6 +/- 0.7, 4.0 +/- 0.8, 3.6 +/- 0.8, and 4.6 +/- 0.3, respectively at the last follow-up visit. Results of about 10 years of follow-up these patients treated with TSRH instrumentation suggest that the method is efficient for the correction of frontal and sagittal plane deformities and trunk balance.