General Session: Adult Spinal Deformity - Hall F

Presented by: N. Stekas

Author(s):

T. Protopsaltis(1), S. Ramchandran(1), J. Tishelman(1), N. Stekas(1), N. Frangella(1), J. Smith(2), D. Sciubba(3), P. Passias(1), R. Lafage(4), E. Klineberg(5), V. Lafage(4), R. Hart(6), D. Burton(7), C. Shaffrey(2), F. Schwab(4), C. Ames(8), 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) Hospital for Special Surgery, New York, NY, United States
(5) University of California-Davis, Sacremento, CA, United States
(6) Swedish Neuroscience Institute, Seattle, WA, United States
(7) University of Kansas Medical Center, Kansas City, KS, United States
(8) University of California, San Francisco, CA, United States

Abstract

Introduction: Patients with severe cervical deformity (CD) endure disability, pain, and poor HRQL, which can persist following corrective surgery. Horizontal gaze, as measured by Chin Brow Vertical Angle (CBVA) is a marker of cervical deformity that has been correlated to poor quality of life. CBVA is typically less accessible than other cranial or cervical measurements due to the technical requirements of the radiograph. The slope of McGregor's line (McGS) is widely considered a surrogate measure and a proxy for CBVA. A post-operative C2-C7 Sagittal Vertical Axis (cSVA) greater than 4cm is representative of forward sagittal deformity of the cervical spine and a larger cSVA has been correlated with greater disability. The present study hypothesized that horizontal gaze disruption (measured by McGS) and severe forward cervical malalignment after corrective surgery are associated with worse post-operative patient-reported outcomes.

Methods: Retrospective review of a prospective, multi-center CD database was conducted. Database inclusion criteria were cervical kyphosis (CK) >10°, cervical scoliosis (CS) >10°, C2-7 SVA > 4cm or CBVA>25°. Patients were categorized by high (>10°) and low (< 10°) McGS and severe preoperative sagittal deformity (cSVA > 4cm). The demographic, surgical, and radiographic parameters were compared. Relative visibility of CBVA and McGS on x-ray was assessed. 1-year post-operative health status was examined using the Neck Disability Index (NDI), EQ-5D and (NSR) neck and arm. Established radiographic parameters were analyzed by paired and independent samples t-tests.

Results: 115 CD patients over age 18 (56% female, mean age 62, 41% revisions) were studied. CBVA was visible on x-ray in 17% of CD patients as compared to 90% visibility of McGS. High McGS was associated with poorer cSVA (58.6 vs 33.0 cm, p < .001) and TS-CL (58.2 vs 31.8°, p < .001). High McGS patients had more consecutive kyphotic levels in the upper cervical spine (64% vs 37%, p < .001) and below C5 (68% vs. 26%, p = .012). Both cohorts' NDI, EQ-5D, and NRS-neck scores improved at 1 year post-op (both p< .01), along with NRS neck rating (p< .01). However, in horizontal gaze disrupted patients, 1-year post-op McGS was associated with poorer NDI (r=.302, p=.012). Among those with post-operative cSVA >4cm, post-operative C2 slope was positively correlated with worse NDI (R=0.32, p=0.03) and EQ5D (R=-0.43, p=0.004), and cSVA was positively correlated with NSR neck (R=0.3, p=0.05).

Conclusion: These findings underscore the importance of correcting forward cervical alignment to improve pain and quality of life measures in patients with severe CD. Specifically, restoration of horizontal gaze, C2 slope and cSVA are critical in improving HRQL. Corrective surgery for CD improved HRQL in all patients. However, a greater post-operative McGS is indicative of pain and disability in CD patients. McGS is more visible, and easily assessed, on spinal x-rays than CBVA. Correcting patients' McGS, cSVA, and C2 slope to within normal ranges should be a priority in surgical treatment for CD patients.