An analysis of preoperative shoulder and neck balance and surgical outcome in 111 adolescent idiopathic scoliosis patients with two subtypes of Lenke 1 curves
Document Type
Article
Publication Date
1-1-2021
Abstract
OBJECTIVE The incidence of postoperative shoulder imbalance following posterior spinal fusion (PSF) is still high in Lenke 1 curves despite following current treatment recommendations for upper instrumented vertebra (UIV) selection. The objective of this retrospective study was to identify differences in preoperative shoulder balance and to report the surgical outcome of two subtypes of Lenke 1 curves (flexible vs stiff) in patients with adolescent idiopathic scoliosis (AIS). METHODS The authors grouped patients' curves as Lenke 1-ve (flexible) when their preoperative proximal thoracic side bending (PTSB) Cobb angle was < 15 degrees and as Lenke 1+ve (stiff) when the PTSB Cobb angle was 15 degrees-24.9 degrees. The authors hypothesized that these two subtypes had distinct preoperative and postoperative shoulder and neck balance following PSF using pedicle screw constructs. RESULTS Fifty patients had Lenke 1 (flexible) curves and 61 had Lenke 1 (stiff) curves. The mean preoperative T1 tilt for patients with Lenke 1 (flexible) was -4.9 degrees 5.3 degrees, and for those with Lenke 1 (stiff) curves it was -1.0 degrees +/- 5.3 degrees (p < 0.001). Mean cervical axis (CA) was -0.1 degrees +/- 3.2 degrees for Lenke 1 (flexible) curves and 2.3 degrees +/- 3.5 degrees for Lenke 1 (stiff) curves (p < 0.001). Preoperative radiographic shoulder height (RSH) and clavicle angle (Cla-A) were similar between the two curve subtypes. Following surgery, there were significant differences between the subtypes in terms of T1 tilt (p < 0.001), RSH (p = 0.014), and Cla-A (p = 0.031). Interestingly, 41.0% of patients with a Lenke 1 (stiff) curve had +ve T1 tilt compared to 2.0% in Lenke 1 (flexible) group. Moreover, 26.2% of patients with the Lenke 1 (stiff) curve had +ve RSH compared to 12.0% of those with Lenke 1 (flexible) curves. And, 24.6% of patients with Lenke 1 (stiff) had +ve Cla-A compared to 10.0% of those with Lenke 1 (flexible) curves. CONCLUSIONS Lenke 1 (flexible) and Lenke 1 (stiff) curves had distinct preoperative T1 tilt and CA measurements. Following PSF, the authors noted +ve T1 tilt in 41% of patients with Lenke 1 (stiff) curves versus 2.0% in those with Lenke 1 (flexible) curves. The authors also noted a significant difference in postoperative RSH and Cla-A measurements.
Keywords
Adolescent idiopathic scoliosis, Lenke 1, Subtype, Cervical supine side bending, Proximal thoracic, Shoulder, Neck, Imbalance, Cervical axis, T1 tilt, Upper instrumented vertebra, Deformity
Divisions
ortho
Publication Title
Journal of Neurosurgery-Spine
Volume
34
Issue
1
Publisher
American Association Neurological Surgery
Publisher Location
5550 MEADOWBROOK DRIVE, ROLLING MEADOWS, IL 60008 USA