Evaluation of the Factors Affecting the Loss of Lumbar Lordosis in Surgical Treatment of Patients with Adolescent Idiopathic Scoliosis Using Segmental Instrumentation

Background The identification of independent factors affecting the loss of lumbar lordosis can facilitate programmed surgery in adolescent idiopathic scoliosis (AIS) patients especially with considering the importance of sagittal characteristics. Objectives This study aimed to investigate the factors affecting the amount of the loss of lumbar lordosis in surgical treatment of the patients with AIS using segmental instrumentation. Methods In this study which was conducted in three years, 91 AIS patients who underwent segmental instrumentation were studied and 63 patients remained in the study according to the inclusion criteria. All patients’ information was recorded on admission in separate forms and radiography results were coded and archived before the surgery for more evaluation. All patients were subject to standing whole spine radiograph again 12 months after the surgery. Ultimately, the information was put into predetermined forms and was used for a statistical analysis after the completion of forms. Results The mean age of the patients was 15.62 ± 3.09 years. The mean preoperative lumbar lordosis was 45.25 ± 12.17 degrees and the mean preoperative thoracic kyphosis was 41.54 ± 16.31 degrees. The mean postoperative lumbar lordosis was 34.37 ± 10.26 degrees. The mean postoperative thoracic kyphosis was obtained 26.56 ± 9.17. The mean surgical correction of thoracic kyphotic deformity and lumbar lordosis were correlated with each other with the correlation coefficient of 0.71 (P < 0.001). Men have more (16.62 ± 8.74) loss of lumbar lordosis than women (10.05 ± 8.53) (P < 0.001). There was not any significant correlation between the type (hook/hybrid) of the instrumentation with the loss of lumbar lordosis (P = 0.07, P = 0.41). Conclusions Considering the findings of this study, the most important factor affecting the amount of post-operative loss of lumbar lordosis in segmental instrumentation in AIS patients is the amount of the correction of thoracic kyphosis. So that, the greater the amount of the correction of thoracic kyphosis, the more the loss of lumbar lordosis. Men, also, have a more loss of lumbar lordosis.