Restoration of Thoracic Kyphosis in Adolescent Idiopathic Scoliosis Over a Twenty-Year Period

Are We Getting Better?

Blake M. Bodendorfer, MD; Suken A. Shah, MD; Tracey P. Bastrom, MA; Baron S. Lonner, MD; Burt Yaszay, MD; Amer F. Samdani, MD; Firoz Miyanji, MD; Patrick J. Cahill, MD; Paul D. Sponseller, MD; Randal R. Betz, MD; David H. Clements 3rd, MD; Lawrence G. Lenke, MD; Harry L. Shufflebarger, MD; Michelle C. Marks, PT, MA; Peter O. Newton, MD

Disclosures

Spine. 2020;45(23):1625-1633. 

In This Article

Materials and Methods

Institutional review board approval for the study was obtained locally from each contributing institution's review board, and consent was obtained from each patient prior to data collection. A review of a multicenter prospective database of patients with AIS who underwent surgical correction was performed. A query to include all patients with a diagnosis of main thoracic scoliosis (Lenke types 1–4) from 1995 to 2015 was performed. A total of 1063 patients with preoperative 3D thoracic hypokyphosis (<10°) and 2-year follow up were identified. Patients were divided into the following operative cohorts: Period 1 (1995–2000, n = 52), Period 2 (2001–2009, n = 528), and Period 3 (2010–2015, n = 483). These time ranges were chosen based on shifts in operative approaches to correct thoracic scoliosis in this study group (i.e., predominantly anterior from 1995 to 2000, a shift to posterior with pedicle screws from 2001 to 2009, and almost exclusively posterior using contemporary techniques in addition to screws from 2010 to 2015).[39] To further analyze operative cohorts, the patients who underwent isolated ASF with instrumentation (n = 91), early PSF from Period 2 (2001–2009, n = 444), and contemporary PSF from Period 3 (2010–2015, n = 462) were also divided into separate groups. Fusion levels and correction techniques were gathered when available. Patients' pre- and postoperative TK at 2-year follow-up were collected, as were the differences in these values and the percentage of patients in each cohort achieving greater than 20° of TK at 2 years postoperatively, which was defined as the desired thoracic sagittal outcome. All radiographs were measured by a standard observer not involved in the surgeries. A validated formula for assessing 3D T5-T12 sagittal alignment using measured two-dimensional (2D) T5–T12 kyphosis for thoracic AIS was applied, since true kyphosis is under measured with 2D methods in a rotated scoliotic spine.[40,41] Sagittal alignment from T5 to T12 was utilized in this study (as opposed to entire thoracic sagittal alignment) based on the majority of the apical levels in thoracic scoliosis occurring within this region, the study group's emphasis on kyphogenic restoration in this region, and the Lenke classification's emphasis on the T5–T12 sagittal profile.[42] Statistical data were analyzed using SPSS (SPSS Inc, Chicago, IL). Each variable was reported as the mean ± standard deviation. Two-way repeated measures analysis of variance grouped by time interaction and a post-hoc Bonferroni correction to adjust for multiple comparisons was utilized, with P < 0.05 considered significant.

processing....