501 - Sagittal Spinal and Pelvic Parameters in Patients with Scheuermann’s D...

Oral Posters: Adult Spinal Deformity

Presented by: I. Lieberman - View Audio/Video Presentation (Members Only)

Author(s):

S. Farhan(1), M. Eichler(1), X. Hu(2), I. Lieberman(2), T. Belanger(3), A. Pendi(1), S. Bederman(4)

(1) University of California Irvine, Irvine, CA, United States
(2) Texas Back Institute, Texas Health Presbyterian Hospital Plano, Scoliosis and Spine Tumor Center, Plano, TX, United States
(3) Texas Back Institute, Plano, TX, United States
(4) Restore Orthopedics & Spine Center, Orange, CA, United States

Abstract

Introduction: Maintaining and/or restoring sagittal spinopelvic balance has been recognized as one of the most important factors in optimizing the patients' outcome after spinal reconstruction surgeries. However, sagittal spinopelvic parameters are still poorly defined in patients with Scheuermann's Disease (SD). The excessive thoracic kyphosis (TK) and/or thoracolumbar kyphosis (TLK) in SD patients is not reflected in pelvic parameters which could lead to inaccurate preoperative planning and a less than desirable surgical outcome. The purpose of this study is to verify the relationship between sagittal spinopelvic parameters in skeletally mature SD patients.

Methods: In adult deformity surgery, PI-LL (Pelvic incidence to Lumbar lordosis Mismatch, PLM) =±10° has been proven to be the ideal spinopelvic alignment for better clinical outcomes. However, it was recently reported that patients with SD have significantly lower PI and there exists no relationship between PI and LL which may be a reflection of the body's compensation for the excessive TK and/or TLK. Thoracic hyperkyphosis is commonly defined as ≥ 45° and it has been reported that PI-LL+TK≤45° is very sensitive for predicting ideal sagittal balance in patients undergoing deformity surgery. Given that normal TLK approximates 0°, we propose the following formula in SD patients: Δ=(TK-45°)+TLK+PLM which should be ±10° if properly balanced. We then retrospectively identified all skeletally mature SD patients without prior spine surgery at two spine centers between 2006 and 2015 and validated the proposed formula (Δ) with standard sagittal radiographic parameters. T1 pelvic angle (TPA) was used as a measure of global balance with a normal maximum of 15°.

Results: A total of 30 patients were included in this study (15 male, 15 female). The patients' mean age was 39 years (range 18-71). The average value of Δ was 2.4° (range between -28° and 74°) and the mean absolute value of Δ was 16.7°±14.5°. There was a statistically significant and strong correlation between Δ and both TPA (R2=0.75) and PT (R2=0.69). At the maximal normal TPA for a sagittal balanced adult (15°), Δ yielded a maximum of 9.2°. There were 21 patients whose TPA≤15° and their mean Δ was -8.7°±11.6°. There were 9 patients whose TPA>15° and their mean Δ was 28.2°±19.7° (p=0.0003).

Conclusion: Our results shows that Δ=(TK-45°)+TLK+PLM maintained within ±10° could be a valuable formula to evaluate the global sagittal balance in skeletally mature SD patients. This formula may help us better plan for surgical correction in patients with SD. Further study is underway to evaluate if maintaining and/or restoring a normal Δ is associated with better clinical outcomes in SD patients who were operated for lumbar degenerative diseases.

Fig. 1