Lightning Podiums: Adult Spinal Deformity - Room 801A

Presented by: L. Steinmetz


A. Buckland(1), P. Zhou(1), J. Moon(1), J. Tishelman(1), B. Beaubrun(1), L. Steinmetz(1), S. Horn(1), N. Stekas(1), D. Vasquez-Montes(1), G. Poorman(1), T. Errico(1), T. Protopsaltis(1), J. Vigdorchik(1)

(1) New York University Langone Orthopedic Hospital, Division of Spinal Surgery, New York, NY, United States


Introduction: Postural changes between sitting and standing alter thoracolumbar alignment and pelvic tilt. This has implications in total hip arthroplasty and potentially for proximal spinal alignment when the lumbar spine has degenerated or is fused. The aim of this study was to discern changes in lumbopelvic alignment between sitting and standing in patients with normal, degenerative, and fused lumbar spines.

Methods: Radiographic evaluation was performed on patients undergoing full-body standing and sitting stereoradiographic assessment for spinal surgery or THA planning. Radiogaphic measurements included pelvic incidence (PI), Pelvic Tilt (PT), Sacral Slope (SS), Lumbar Lordosis (LL), L1-L4 lordosis and L4-S1 lordosis and PI-LL. Patients were categorized into three groups: Normal, Degenerative, and Fusion based on radiographic assessment. The difference between groups and standing to sitting were compared with ANOVA and t-test respectively. Stepwise linear regression was performed to develop a formula to predict sitting PT from a standing lateral radiograph.

Results: Of 116 patients, 52 (44.8%) had normal spines, 55 (47.4%) were degenerative, and 9 (7.8%) had spinal fusions. There was a significant change in radiographic parameters from standing to sitting in the normal (PT 13.29° to 27.44°, PI-LL -3.42° to 18.86°, L1-L4 -21.96° to -14.35°, L4-S1 -35.16° to -20.64°, all p< 0.001) and degenerative (PT 18.06° to 27.64°, PI-LL -4.98° to 17.64°, L1-L4 -19.80° to -14.76°, L4-S1 -30.47° to -24.31°, all p< 0.001) with the normal group having the greatest change. No significant changes were found in the fusion group (All p>0.1). In normal patients, sitting PT correlated most strongly with standing PI (R=0.589) and standing L1-L4 (R=0.399). Sitting PT was able to be predicted with formula: Sitting PT = (1.294*Standing PI) + (1.143* Standing PT) + (0.378 * L1-L4) + (0.826 * L4-S1) + 10.765 (R=0.700). In degenerative patients, sitting PT correlated with standing L4-S1 (R=0.229), and PI (R=0.122), with Sitting PT = (0.447 * Standing PI) - (0.347 * Standing PT) + (0.174 * L1-L4) + (0.549 * L4-S1) + 29.406 (R=0.368). Sitting PT in fusion patients correlated with standing PT (R=0.903), number of lumbar levels fused (R=0.621), PI (R=0.612), L1-L4 (R=0.354) and L4-S1 (R=0.210). Sitting PT was able to be predicted in fusion patients by (1.290 * Standing PT) + (2.971 * Levels Fused) - 15.512 (R=0.951).

Conclusions: Lumbopelvic alignment changes with sitting and standing. Sitting alignment may be predicted accurately in patients with normal lumbar spines and lumbar fusion.