Do Thoracolumbar/lumbar Curves Respond Differently to Growing Rod Surgery Compared With Thoracic Curves?

STUDY DESIGN: Retrospective study.

OBJECTIVES: To compare radiographic outcomes between primary thoracic and primary thoracolumbar/lumbar curves in patients with early-onset scoliosis (EOS) after growing rod (GR) surgery.

SUMMARY OF BACKGROUND DATA: Previous studies have shown the efficacy of GR surgery for progressive EOS. However, there is no information on the behavior of different curve patterns in EOS after GR surgery.

METHODS: A multicenter international EOS database query identified 175 patients who met the following inclusion criteria: non-congenital etiology, GR surgery, ≤ 10 years of age at index surgery, minimum 2-year follow-up, and at least 3 lengthenings. Patients were categorized into 2 groups based on the Scoliosis Research Society definition of the anatomical location of primary curves: group 1 included thoracic apices (T2 to T11/12 disc) and group 2 included thoracolumbar (T12 to L1) and lumbar (L1/2 disc to L4) apices. Radiographic measurements were performed before and after index surgery and at latest follow-up.

RESULTS: A total of 139 patients (79%) had primary thoracic (group 1) and 36 (21%) had primary thoracolumbar or lumbar curves (group 2). Mean number of levels instrumented was statistically greater in group 2 (15.0) versus group 1 (13.6) (p < .05). Group 2 had statistically better mean curve correction than group 1 after the index GR surgery (51% and 44%, respectively; p < .05). However, there was no significant difference in mean percent curve correction at latest follow-up (46% and 39%, respectively; p > .05). Implant complication rate was 45% and 47% for groups 1 and 2, respectively. Preoperative curve flexibility was greater in group 2 (45%) compared with group 1 (40%) (p > .05).

CONCLUSIONS: Overall, thoracolumbar/lumbar and thoracic curves achieve similar major curve correction and have a similar complication profile.