Prognosis of spontaneous thoracic curve correction after the selective anterior fusion of thoracolumbar/lumbar (Lenke 5C) curves in idiopathic scoliosis

Abstract

Background context: Prognosis of minor lumbar curve correction after selective thoracic fusion in idiopathic scoliosis is well defined. However, the prognosis of minor thoracic curve after isolated anterior fusion of the major lumbar curve has not been well described.

Purpose: To define the prognosis of spontaneous thoracic curve correction after selective anterior fusion of the lumbar/thoracolumbar curve in idiopathic scoliosis.

Study design: A retrospective cohort study on the prognosis of the minor curve after selective anterior correction and fusion of the lumbar/thoracolumbar curve in idiopathic scoliosis.

Patient sample: Idiopathic lumbar scoliosis patients treated with anterior spinal fusion.

Outcome measures: The Scoliosis Research Society 22 questionnaire was used as an outcome measure at the final follow-up.

Methods: Twenty-eight patients were included in this study. Four patients were male, 24 patients were female, and average age at the time of surgery was 16 years. Mean follow-up was 48 months. According to the Lenke Classification, 22 patients were 5CN, 5 were 5C-, and 1 was 5C+. All operations were performed in the same institution. Standing long posterior-anterior and lateral radiographs were taken just before surgery, 1 week after surgery, and at final follow-up.

Results: The mean preoperative Cobb angle of the lumbar (major) curve was 53° (standard deviation [SD]=8.6) and that of the thoracic (minor) curve was 38.4° (SD=6.24). The lumbar and thoracic curves were corrected to 10° (SD=7.6) and 25° (SD=8.3) postoperatively and measured 17° (SD=10.6) and 27° (SD=7.7), respectively, at the last follow-up. There was a significant difference between the preoperative and postoperative measurements of the minor curves (p<.05). However, there was no significant difference between the early postoperative and the final follow-up measurements (p>.05). Regarding the overall sagittal balance, there was no significant difference between preoperative, early, and late postoperative measurements (p>.05).

Conclusions: Selective anterior fusion of the major thoracolumbar/lumbar curve was an effective method for the treatment of Lenke Type 5C curves. Minor thoracic curves did not progress after selective fusion of thoracolumbar/lumbar curves in minimum 2-year follow-up.

Keywords: Anterior spinal fusion; Idiopathic scoliosis; Minor curve; Prognosis; Selective fusion.