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Published on: August 6, 2019
Range of Horizontal Gaze Following Multilevel Posterior Cervical Fusion Across the Cervicothoracic Junction
Clayton Hoffman1, Shahbaaz A Sabri2, Michael Nocek3
1Department of Orthopedic Surgery, School of Medicine, University of Colorado, Anschutz Medical Campus, Aurora, CO.
Study Design:
Retrospective single-institution case series.
Objective:
Our purpose was to determine if extension of fusion across the cervicothoracic junction (CTJ) during multilevel posterior cervical fusion (PCF) can significantly affect patients' horizontal gaze and potentially inform how spine surgeons approach fusion across the CTJ.
Summary Of Background Data:
The natural head posture and horizontal gaze are important factors affecting balance and line of sight. Patients with severe spinal deformity often have an abnormal ascended gaze contributing to patients' disabilities.
Methods:
We included patients 18-100 years old who underwent PCF involving ≥3 segments with caudal endpoints of C7-T3. Primary outcome measures included radiographic measurements of McGregor slope (McGS), C0-C2 Cobb angle, C7-T1 Cobb angle, C2-C7 cervical lordosis (CL), T1 slope, and cervical sagittal vertical axis (cSVA) on standing standard lateral cervical X-rays in neutral, flexion, and extension before and after PCF by 2 independent evaluators.
Results:
One hundred eighty-eight patients were included: female 133 (70.7%); mean age 60.9 years old; group 1 (C7 caudal fixation) 104 (55.3%), and group 2 (T1-T3 caudal fixation) 84 (44.7%). In all patients, the full range of horizontal gaze (McGS) decreased by an average of 17.3 degrees (P<0.0001), while C0-C2 Cobb angle flexion-extension increased by an average of 4.1 degrees (P<0.0001). The range of McGS was not significantly different between group 1 and group 2; however, motion at C0-C2 increased by 3.5 degrees more in group 2 (P=0.034).
Conclusions:
Multilevel PCF significantly decreases the full range of horizontal gaze despite a compensatory increase of C0-C2 range of motion. While the caudal endpoint does not significantly affect the change in the range of horizontal gaze, constructs that terminate distal to the CTJ (T1-T3) see a significantly increased C0-C2 range of motion. When considering crossing the CTJ, surgeons should understand that while the range of horizontal gaze may not differ, this may result in increased motion across the C0-C2 junction.
Levels Of Evidence:
Level IV.