Global spinal deformity from the upper cervical perspective. What is “Abnormal” in the upper cervical spine?
Peter G Passias1, Haddy Alas1, Renaud Lafage2, Bassel G Diebo3, Irene Chern1, Christopher P Ames4, Paul Park5, Khoi D Than6, Alan H Daniels7, D Kojo Hamilton8, Douglas C Burton9, Robert A Hart10, Shay Bess11, Breton G Line11, Eric O Klineberg12, Christopher I Shaffrey13, Justin S Smith13, Frank J Schwab2, Virginie Lafage2
1 Department of Orthopaedic and Neurosurgery, Division of Spinal Surgery, NYU Medical Center, NY Spine Institute, New York, NY, USA
2 Department of Orthopedics, Hospital for Special Surgery, New York, NY, USA
3 Department of Orthopedic Surgery, SUNY Downstate, New York, NY, USA
4 Department of Neurological Surgery, University of California, San Francisco, CA, USA
5 Department of Neurologic Surgery, University of Michigan, Ann Arbor, Michigan, USA
6 Department of Neurosurgery, Oregon Health Sciences University, Portland, OR, USA
7 Department of Orthopaedic Surgery, Warren Alpert School of Medicine, Brown University, Providence, RI, USA
8 Department of Neurological Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
9 Department of Orthopaedic Surgery, University of Kansas Medical Center, Kansas City, KS, USA
10 Department of Orthopaedic Surgery, Swedish Neuroscience Institute, Seattle, WA, USA
11 Department of Spine Surgery, Denver International Spine Center, Presbyterian St. Luke's/Rocky Mountain Hospital for Children, Denver, CO, USA
12 Department of Orthopaedic Surgery, University of California, Davis, CA, USA
13 Department of Neurosurgery, University of Virginia Medical Center, Charlottesville, VA, USA
Peter G Passias
Department of Orthopaedic and Neurosurgery, NYU Medical Center - Orthopaedic Hospital, New York Spine Institute, 301 East 17th St., New York, NY 10003
Source of Support: None, Conflict of Interest: None
Hypothesis: Reciprocal changes in the upper cervical spine correlate with adult TL deformity modifiers.
Design: This was a retrospective review.
Introduction: The upper cervical spine has remarkable adaptability to wide ranges of thoracolumbar (TL) deformity.
Methods: Patients >18 years with adult spinal deformity (ASD) and complete radiographic data at baseline (BL) and 1 year were identified. Patients were grouped into component types of the Roussouly classification system (Type 1: Pelvic incidence [PI] <45° and lumbar lordosis [LL] apex below L4; Type 2: PI <45° and LL apex above L4; Type 3:45°r assessed changes in BL upper cervical parameters (C0-2, C0 slope, McGregor's Slope [MGS], and CBVA) across groups.
Results: A total of 343 ASD patients were analyzed. When grouped by BL Schwab and Roussouly, Group P had the lowest BL disability compared to other Groups, while Roussouley Type 1 correlated with higher BL disability compared to Type 2. Moving cranially up the spine, Group P, Group LP, and Group TL did not differ in C0-2 angle, C0 slope, MGS, or CBVA. Group C had a significantly smaller C0-C2, and more negative MGS, C0 slope, and CBVA than noncervical groups. Type 1 trended slightly higher CBVA and MGS than types 2–4, but no differences in cervical lordosis, C0-C2, or C0S were found. MGS (r = −0.131, P = 0.015), CBVA (r = −0.473, P < 0.001), and C0S (r = −0.099, P = 0.042) correlated most strongly with sagittal vertical axis (SVA) compared to other Schwab modifiers. We found SVA > 34 mm predicted a 1 unit (°°) decrease in MGS (odds ratio [OR]: 0.970 [0.948–0.993], P = 0.010), while cervical SVA >51 mm predicted a 1 unit increase in MGS (OR: 1.25 [1.12–1.38], P < 0.001).
Conclusions: Our study suggests that upper cervical alignment remains relatively stable through most broad variations of adult TL deformity. Changes in SVA correlated most with upper cervical changes.