857 - Does Cervical Flexibility Affect Clinical Outcomes in Patients Undergoing Multi-Level Posterior Cervical Fusions?

Objectives: The purpose of this study was to quantify and compare the imaging measurements between the two imaging modalities and determine if the degree of cervical flexibility had an impact clinical outcome.

Design: This study assessed 227 adult patients who underwent a three or more level posterior cervical fusion. Data collected included demographics, smoker status, radiographic measurements (T1 Slope, C2-C7 Lordosis, C2-C7 Sagittal Vertical Axis) from both XR films and MRI/CT scans, surgical and complication, as well as patient reported outcome measures for pain (Visual Analog Scale, VAS) and disability (Oswestry Disability Index, ODI). For each measurement technique, three cohorts were created based on distribution of the Δ between XR and MRI/CT values.

Results: Overall, the cohort (227) was 53.7% female, with a mean age of 63 ± 13 years. Median Δ T1 Slope was 9°. T1 Slope cohorts: Group I with a Δ of < 4°; Group II ≥4° to < 15°; Group III ≥15°. Significant differences between Group I and Group III existed in VAS and ODI. For Δ C2-C7 Lordosis, the median Δ value was 4°; Group I had a Δ lordosis of < 2°; Group II ≥2 to < 7°; Group III ≥7°. Median Δ C2-C7 SVA was 14.37mm. SVA Group I had a Δ of < 7.87mm; Group II ≥7.87mm to < 27.82mm; Group III ≥27.82mm. There were significant differences between Group I and Group III in VAS and ODI. Revision and complication rates positively correlated with increased Δ measurement. Age had a significant effect on Δ C2-C7 SVA.

Conclusions: Larger Δ or cervical flexibility between XR and MRI/CT measurements are positively correlated with higher complication and revision rates. Patients with greater incidences of cervical flexibility reported significantly higher pain and disability scores compared to those with lower measurement Δ. Age was found to significantly impact Δ SVA measurement.