Is There a Cervical Alignment Threshold Warranting Cervical Inclusion in the Construct?
Peter G. Passias, Mohammad Daher, David Liu, Francesca Totis, Drew Millar, Sang Hun Lee, Pratibha Nayak, Themistocles Protopsaltis, David Kojo Hamilton, Han Jo Kim, Thomas Buell, John Moon, Justin Scheer, Anthony Mikula, Darryl Lau, Bassel Diebo, Alan H. Daniels, Gregory Mundis, Robert Eastlack, Jeffrey P. Mullin, Khaled Kebaish, Praveen Mummaneni, Munish Gupta, Jeffrey Gum, Breton Line, Richard Hostin, Dean Chou, Eric Klineberg, Ricardo B. V. Fontes, Richard Fessler, Lawrence Lenke, Jay D. Turner, Juan S. Uribe, Stephen Lewis, Renaud Lafage, Virginie Lafage, Frank Schwab, Shay Bess, Justin Smith, Christopher Shaffrey, Christopher Ames,BACKGROUND AND OBJECTIVES:
Postoperative thoracolumbar (TL) realignment in patients with adult spinal deformity (ASD) may induce cervical spine (CS) decompensation. This study identifies predictors of CS decompensation after TL surgery and defines a baseline CS-alignment threshold based on C2-pelvic angle (C2-PA) for CS inclusion in the TL construct.
METHODS:
Patients with ASD undergoing TL fusion to the sacrum with an upper instrumented vertebrae at T2 or below and available baseline radiographs and patient-reported outcome measures (PROMs) were included. CS decompensation was defined as CS surgery or >2 SD above the mean in C2-PA, cervical sagittal vertical axis (cSVA), or T1-slope cervical lordosis (TS-CL) at the studied postoperative time point.
RESULTS:
One thousand one hundred ninety patients were included; 166 (13.9%) had CS decompensation after TL surgery, including 24 (2.0%) requiring CS extension. CS decompensation was identified in 81 patients (6.8%) at 6 weeks (4 (0.3%) extensions), 13 (1.2%) at 6 months (2 (0.2%)), 43 (3.9%) at 1 year (7 (0.6%)), and 29 (2.8%) at 2 years (11 (0.9%)). Patients with CS decompensation at 6 months showed worse global and CS alignment at 6 weeks (lumbar lordosis: 53.6 vs 46.3; cSVA: 30.5 vs 38.5;
CONCLUSION:
Two years after TL ASD surgery, 13.9% had CS decompensation, with 14% requiring CS extension. Baseline CS alignment independently predicted CS decompensation. Patients with preoperative C2-PA >26.2° may benefit from CS inclusion in the TL construct after external validation of this threshold by future research.