The Deformity-Flexibility Quotient Predicts Both Patient Satisfaction and Surgeon Preference in the Treatment of Lenke 1B or 1C Curves for Adolescent Idiopathic Scoliosis

Study Design. Analysis of patient and surgeon preference between selective and nonselective thoracic spinal fusions. Objective. The purpose of this study was: (1) to determine patient preference between a longer, straighter fusion versus a shorter fusion with a residual lumbar deformity, and (2) to determine surgeon preference based on a cross-sectional survey. Summary of Background Data. In the surgical treatment of Lenke 1B and 1C curves, choosing between a selective thoracic fusion which may leave residual lumbar deformity versus a fusion into the lower lumbar spine which may improve correction at the expense of lumbar motion continues to be debated. Methods. The deformity-flexibility quotient (DFQ) was defined to quantify the 2 primary yet competing goals of adolescent idiopathic scoliosis surgery, and is calculated by dividing the residual coronal lumbar deformity by the number of unfused distal motion segments. Patient preference between a selective versus nonselective fusion was determined using a Spearman's Rho analysis to correlate radiographic data (including the DFQ) with Scoliosis Research Society-24 scores. Surgeon preference was determined using a cross-sectional survey of 12 experienced scoliosis surgeons. Results. One hundred fifty-five adolescent idiopathic scoliosis patients were included in the analysis. At 2-year postoperative, the number of distal unfused motion segments averaged 5.8 +/- 1.4 ( range: 2-9) and the residual thoracolumbar/lumbar deformity averaged 20.1 degrees +/- 8.8 degrees ( range: 1 degrees-43 degrees). This resulted in an average DFQ of 3.6 +/- 1.9 ( range: 0.2-12.3). A lower DFQ was found to significantly correlate with improved patient satisfaction scores (r = -0.16, P = 0.04). In the cross-sectional survey, a lower DFQ also predicted the surgeon preferred radiograph in greater than 70% of the pairings. Conclusion. The DFQ quantifies the perceived trade off between residual deformity and spared motion segments. Two-year postoperative patient satisfaction, as measured by the Scoliosis Research Society-24 questionnaire, and surgeon preference, in terms of coronal radiographic outcome, correlated significantly with the DFQ.