Lightning Podiums: Adult Spinal Deformity - Room 801A

Presented by: E. Zgonis

Author(s):

J. Varghese(1), E. Zgonis(2), H. Bao(3), J. Elysee(2), T. Pannu(2), R. Lafage(2), V. Lafage(2), H.J. Kim(2)

(1) SUNY Downstate Medical Center, New York, NY, United States
(2) Hospital for Special Surgery, New York, NY, United States
(3) Nanjing Drum Tower Hospital, Nanjing, China

Abstract

Background: Surgical planning for adult spinal deformity is crucial for achieving ideal post-operative alignment and optimizing outcomes. While the deformity is pre-operatively assessed using spinopelvic alignment on standing radiographs, spinopelvic alignment changes when the patient is recumbent during surgery. To bridge this patient-specific gap, pre-operative supine radiographs may be of use. Thus far, the utility of using supine radiographs in the planning process is not well understood.

Purpose: The purpose of this study is to determine the utility of pre-operative supine radiographs in surgical planning for adult spinal deformity. Study desgin/setting: This was a single surgeon, single center, retrospective review of adult spinal deformity cases between 2013 and 2016.

Patient Sample: 110 patients were included.

Outcome Measures: Pelvic incidence - Lumbar Lordosis mismatch (PI-LL), Sagittal Vertical Axis (SVA).

Methods: Adult spinal deformity patients older than 18 years old who were fused to the sacrum/ilium and had available pre-op standing, pre-op supine, and post-op six week standing X-rays were included. Pre-op standing and supine sagittal alignments were compared to the six-week post-op standing sagittal alignment. Primary and Revision patients at baseline were also compared. Paired t-tests, independent samples t-tests, and correlations were used for this analysis.

Results: Of 144 patients, 110 met the inclusion criteria, with a mean age, BMI, and gender distribution of 65 years old, 27 kg/m2, and 78% Female. 35% of the patients were presented as a revision case at baseline. Pre to Post-op successful realignment was noted (PI-LL: 19° vs. 0°, SVA: 80mm vs. 13mm, p=0.000). Pre-operatively, standing sagittal alignment flattened out when the patient was supine (PI-LL: 19° vs. 11°, p=0.000). The pre-op supine alignment was 9° (p=0.000) closer to the post-op standing alignment than the pre-op standing alignment was (ΔPI-LLStanding to Post-op=-20° vs. ΔPI-LLSupine to Post-op= -11°, p=0.000). This difference was correlated with the pre to post-op change in standing alignment (r=0.488, p=0.000). While both the pre-op standing and pre-op supine PI-LL were significantly higher in revision patients (n=39) than primary patients (n=71), the supine alignment was still closer to the post-op standing alignment achieved than the pre-op standing alignment (Primary ΔPI-LLStanding to Post-op= -20 vs. ΔPI-LLSupine to Post-op= -12, Revision ΔPI-LLStanding to Post-op=-19 vs. ΔPI-LLSupine to Post-op= -10, both p=0.000).

Conclusions: Supine spinopelvic alignment is significantly closer to post-op alignment than is the pre-op standing alignment, regardless of revision status at baseline. As it is more predictive of the surgical correction achieved, acquiring supine radiographs should be routine in the pre-operative planning process. Standing radiographs are for defining the deformity; supine radiographs help plan its correction.