29. C2 SVA: when angles are too complicated and the X-ray image is too small

BACKGROUND CONTEXT The cranial sagittal vertical axis (CrSVA) and the cranial gravity line (CrGL), respectively defined as vertical plumb lines from the center of the skull to the posterior sacral vertical line and the center of the femoral heads/hip axis, are superior to the C7 SVA and better predict HRQOL. The T1 pelvic angle (T1PA) is an angular parameter that obviates the need to account for compensatory mechanisms distally such as knee flexion. Global tilt (GT) is another angular parameter and is an important feature of the GAP score. Long cassette films that incorporate the femoral heads and the skull simultaneously are often difficult to obtain, especially in the intraoperative setting. We sought to study other possible substitutes for the CrSVA and CrGL that could be applied in the setting of more limited radiographic resources. PURPOSE C2 SVA, which requires neither skull nor femoral heads, will provide statistically significant correlation to health-related quality of life measures (HRQOL) and to previously established sagittal plumb line and global angular sagittal parameters. STUDY DESIGN/SETTING Retrospective observational cohort. PATIENT SAMPLE A cohort of 53 operative patients including adult and adolescent deformity cases were selected and analyzed. OUTCOME MEASURES Preoperative baseline sagittal parameters, including C2SVA, C2GL, C7SVA, CrSVA, CrGL, T1PA, as well as baseline preoperative SRS-22 and ODI. METHODS A cohort of 53 operative patients including adult and adolescent deformity cases were selected and analyzed for preoperative baseline sagittal parameters, including C2SVA, C2GL, C7SVA, CrSVA, CrGL, T1PA, as well as baseline preoperative SRS-22 and ODI. Pearson's r was used to quantify the correlation. RESULTS The C2SVA has a statistically significant correlation with the CrGL [r(51)=0.87; p CONCLUSIONS Validated angular parameters of T1PA and GT have the highest correlation with each other and with SRS-22 and ODI. among plumb line parameters, the C2 SVA has the highest correlation with the T1PA, GT, ODI and SRS-22 scores. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.