Lightning Podiums: Adult Spinal Deformity - Room 801A

Presented by: D. Ge


T. Protopsaltis(1), S. Ramchandran(1), J. Tishelman(1), N. Stekas(1), D. Ge(1), J. Smith(2), B. Neuman(3), G. Mundis(4), R. Lafage(5), E. Klineberg(6), K. Hamilton(7), V. LaFage(5), M. Gupta(8), R. Hart(9), F. Schwab(5), D. Burton((1)0), S. Bess((1)(1)), C. Shaffrey((1)(2)), C. Ames((1)(3)), International Spine Study Group

(1) NYU Langone Orthopedic Hospital, New York, NY, United States
(2) University of Virginia Health System, Charlottesville, VA, United States
(3) Johns Hopkins University, Baltimore, MD, United States
(4) Scripps Clinic San Diego, San Diego, CA, United States
(5) Hospital for Special Surgery, New York, NY, United States
(6) University of California-Davis, Sacremento, CA, United States
(7) University of Pittsburgh School of Medicine and Medical Center, Pittsburgh, PA, United States
(8) BJC Institute of Health at Washington University School of Medicine, Saint Louis, MO, United States
(9) Swedish Neuroscience Institute, Seattle, WA, United States
((1) 0) University of Kansas Medical Center, Kansas City, KS, United States
((1) (1) ) Denver International Spine Clinic, Denver, CO, United States
((1) (2) ) University of Virginia Medical Center, Charlottesville, VA, United States
((1) (3) ) University of California, San Francisco, CA, United States


Introduction: Sagittal malalignment of the cervical spine, defined by cSVA, has been associated with poor postsurgical outcomes. There has been a proliferation of parameters to describe alignment in adult cervical deformity (CD) patients. Current CD measures like cSVA focus on subaxial cervical alignment. TS-CL defines the mismatch between cervical and thoracolumbar alignment. C2-Slope (C2S) is highly correlated with TS-CL and it is a mathematical approximation of TS-CL. Higher postop C2S correlated with worse 1-year HRQL. C2S and T1S can serve as simplified descriptions of cervical and thoracolumbar alignment.

Methods: A prospective database of CD patients was analyzed. Inclusion criteria were cervical kyphosis (CK) >10°, cervical scoliosis (CS) >10°, cSVA >4cm or CBVA>25°. Patients were categorized into two groups and compared based on whether the apex of the deformity was in the cervical (C) or the cervicothoracic (CT) region. X-Ray parameters were correlated to C2S, T1S and 1 year HRQL.

Results: 104 CD pts (C= 74, CT= 30; mean age 61 yrs, 56% women and 42% revision) were included. CT pts had larger deformities with higher cSVA and T1S at baseline (p< .05). C2S correlated with TS-CL (r=.98, p< .001) and C0-C2 angle (C0-C2A), cSVA, CL, T1S (r=.37-.65, p< .001). Correlation of cSVA and C0-C2A was weaker (r= .48, p< .001). In C and CT, C2S correlated with cSVA, C0-C2A, C2-C7A, TK and TS-CL (all p< .05). T1S correlated with C2S, cSVA CL, and TK (p< .05). For CT pts, higher C2S correlated with worse 1 year NDI, mJOA, NRS neck and EQ5D (r>.5, p≤.05); for all pts it correlated with worse EQ5D (r=.28, p=.02). Using linear regression analysis, cSVA of 4cm corresponded to C2S of 36° (r²=.43). Moderate disability by EQ5D corresponded to C2S of 20° (r²=.08). For CT, C2S=17° corresponded to moderate disability by NDI (r²=.4), and C2S=20° by EQ5D (r²=.25).

Conclusion: The C2S correlated with upper cervical and subaxial alignment. C2S correlated strongly with TS-CL (R=.98, p< .001) because C2S is a mathematical approximation of TS-CL. C2S is a useful marker of overall CD, acting as a link between the occipitocervical and cervico-thoracic spine. The C2S defines the presence of a mismatch between cervical lordosis and thoracolumbar alignment required to maintain horizontal gaze. Worse 1y postop C2-Slope correlated with worse HRQL.