Introduction: Sagittal imbalance is recognized as a significant variable that contributes to spinal deformity. Clinical outcomes after spine surgery are known to correlate with sagittal balance (SB). SB is traditionally measured by the C7‐S1 plumb line as demonstrated on a 36‐inch long‐cassette film. Abnormal positive alignment induces compensatory changes within the cervical spine, including increased cervical lordosis and T1 slope. Patients presenting clinically with cervical pathology are not routinely assessed with long‐cassette films. A validated tool that could determine the likelihood of overall spine malalignment using cervical radiographs alone would be of significant clinical and cost saving value.
Methods: A retrospective review of 930 patients that were part of awwcluding demographics, cervical lordosis, and T1 slope were analyzed. Patients were randomized in a 2:1 fashion into either a derivation cohort or a validation cohort.
Results: Of the 930 patients, 384 (41.3%) had a positive SB. The final score for predicting SB greater than +50mm included: BMI >25 (1 point), age >55 years (2 points), and T1 slope > 27o (2 points). A score of ≥3 had a specificity of 63.6% (CI 58.7 ‐ 68.3%) and a sensitivity of 82.9% (CI 77.6–87.3%). The ROC area under the curve was 0.82 (CI95% 0.78–0.85) and 0.81 (CI95% 0.76–0.86) in the derivation and validation cohorts, respectively.
Conclusions: This large multicenter study internally validated a simple score to assess SB based upon cervical radiographs, BMI, and age alone. The preoperative awareness of abnormal SB in patients with cervical pathology might change surgical treatment and clinical outcomes. Patients with high scores would benefit from long‐cassette film evaluation.