Neurosurgery Resident Physician Dell Medical School at The University of Texas at Austin
Introduction: The purpose of this study was to quantify and compare the imaging measurements between the two imaging modalities and determine if cervicothoracic flexibility had an impact on cervical alignment or clinical outcome.
Methods: 227 adult patients who underwent a three or more level posterior cervical fusion were assessed.
Results: Median Δ T1 Slope was 9°, with a range of -1° to 45°. T1 Slope cohorts: Group I with a Δ of < 4°; Group II ≥4° to < 15°; Group III ≥15°. Significant differences between Group I and III existed in VAS (4.19 and 6.59) and ODI (35.4 and 45.9). For Δ C2-C7 Lordosis, the median Δ value was 4°, with a range of -11° to 44°; Group I had a Δ lordosis of < 2°; Group II ≥2 to < 7°; Group III ≥7°. Significant differences between Group I and III existed in VAS (4.6 and 6.3) and ODI (36.7 and 45.5). Median Δ C2-C7 SVA was 14.37mm, with a range of 37.6mm to 110.2mm. 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 III in VAS and ODI. Revision and complication rates positively correlated with increased Δ measurement. Effect of age, sex, gender, BMI and smoking status on each measurement technique demonstrated age having a significant effect on Δ C2-C7 SVA.
Conclusion : Larger Δ or cervical and upper thoracic flexibility between XR and MRI/CT measurements are positively correlated with higher complication and revision rates. In those patients in whom the delta between the simulated T1 slope from supine studies and the upright T1 slope was higher were found to have much greater post-operative cSVAs and reported significantly higher pain and disability scores compared to those with lower measurement Δ. Age was found to significantly impact Δ SVA measurement. Upper thoracic flexibility should be considered in selecting fusion levels and alignment goals in patients undergoing posterior cervical fusion surgery.
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