Realignment of Ideal Lumbar Lordosis in Correction Surgery: A Novel Predictive Formula

Study design: Retrospective cohort studySummary of Background Data：Restoring the sagittal balance is the significant procedure, which could be evaluated by the relationship of thoracic kyphosis (TK) and lumbar lordosis (LL). Several lumbar lordosis predictive formulas have been proposed. But previous study ignored importance of reciprocal relationship between regional spinal modifications in some ways.Objectives: Realignment of the lumbar lordosis is fundamental in spinal surgery and several formulas have been established to predict the appropriate lumbar lordosis. However, the predictive accuracy of these formulas did not reach their targets. The present study introduced a novel predictive formula for realignment of lumbar lordosis in correction surgery, aiming to predict the individualized ideal lumbar lordosis for different patients.Methods: A total of 311 asymptomatic volunteers were recruited: 220 volunteers for the development of the formula, and the other 91 subjects for validation. General and radiological parameters were evaluated. Correlation analysis between maxLL and other parameters was performed. Multiple regression analysis was conducted to establish the predictive formula using variables related to maxLL. Comparison between predicated maxLL yielded by our formula and other 7 formulas and actual maxLL were conducted to determine the reliability and validity of our predictive formula.Results: MaxLL was correlated with maxTK, SS, PT and PI (all P<0.05). The adjusted multiple regression analysis showed that there were significant associations of maxLL with maxTK and PI (all P<0.001), and the formula was established as follows: maxLL=0.6*maxTK+0.5*PI+3. No significant difference was found between actual maxLL and predicted maxLL yielded by our formula (P=0.408), and our predictive formula has been demonstrated sound reliability and validity. Conclusion: MaxTK and PI were the primary contributors to maxLL, and our novel formula could be safely utilized to predict the ideal lumbar lordosis for patients before surgery.