Introduction: The aim of our study was to assess the influence of operative changes in spinopelvic parameters on cervical alignment in ASD pts.
Methods: 171 ASD pts =18yrs were assessed for changes from baseline to the 2-yr F/U (base-2yr) in the: C2-C7 sagittal vertical axis (C2-C7 SVA), T1-slope (T1S), and C2-C7 lordosis (C2-C7Lord). Multivariate models were constructed to analyze the influence of: UIV selection (T9 and below vs. above T9), and operative changes from baseline to 6-weeks (base-6wk) in the following spinopelvic parameters: thoracic kyphosis (TK), lumbar lordosis (LL), C7-S1 SVA, pelvic incidence, pelvic tilt and sacral slope.
Results: The base-2yr changes in C2-C7 SVA and in T1S were both significantly associated with the surgical changes from base-6wk in TK, LL and with the UIV selection (Figure 1). Interestingly, the operative correction of C7-S1
SVA from base-6wk was not significantly associated with either changes in C2-C7 SVA or T1S over the 2-yr F/U. Multivariate model revealed that changes from base-2yr in the C2-C7Lord were associated with the base-6wk changes in the C7-S1 SVA (P=0.004). The majority of changes in the C2-C7 SVA over the 2-yr F/U occurred in the first 6 weeks after surgery (base-2yr 95% CI: -0.1mm to +4.6mm, and base-6wk 95% CI: +0.7mm to +4.7mm). Over the 2-yr F/U, on average, there was loss of C2-C7Lord, majority of which was lost in the first 6 weeks after surgery (base-2yr 95% CI: -3.2 to +0.5deg, and base-6wk 95% CI: -4.8 to -1.2deg).
Conclusions: Reciprocal changes in cervical alignment occur in response to operative changes in TK, LL and C7-S1 SVA. Cervical alignment is also influenced by UIV selection. Majority of changes occur in the first 6 weeks and persist over 2-yrs.
Patient Care: This research will improve patient care by identifying key variables (TK, LL, C7-S1 SVA, UIV) that are associated with cervical alignment and reciprocal changes after ASD surgery.
Learning Objectives: By the conclusion of this session, participants should be able to: 1) understand the effects of changes in TK, LL and C7-S1 SVA on cervical alignment, 2) understand the effect of UIV selection on cervical reciprocal changes, and 3) recognize that the majority of changes occur in the first 6 weeks after surgery and persist.