Lightning Podiums: Adult Spinal Deformity - Room 801A

Presented by: E. Zgonis


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


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.