Introduction: Cervical sagittal alignment parameters and their association with PJK has not been clearly delineated in Adult Spinal Deformity (ASD) patients.
Methods: A retrospective review of a prospective multicenter database of ASD patients. Inclusion criteria: >18 years old, ASD. Patients were then separated into those with PJK (Group P) and those without PJK (Group N). Cervical Sagittal Radiographic parameters collected included C2-7 SVA, Cervical Lordosis (CL) and T1 Slope (T1S). Comparisons were made at baseline, 6-week post-op and 1 year post-op. Statistical Analysis was performed with a Fischer Exact T-Test for continuous variables with a p-value <0.05 as significant.
Results: Of the 448 patients in the database, 239 met inclusion criteria for the study and 190 had complete radiographic data for analysis. The incidence of PJK was 30% (57/190). All demographics, except for age were similar between groups (62.6 vs. 60.3 Group P vs. N, p =0.02) Group P had similar baseline cervical sagittal alignment parameters compared to Group N (Table 1). However, post-operatively, Group P demonstrated a higher C2-7 SVA and a significantly greater pre and post-op C2-7 SVA difference while maintaining similar T1S-CL values. Other radiographic risk factors that reached significance at 6 weeks and 1 year post-operatively in the PJK group were a higher C2-T1-vertical angle. Pelvic Tilt (PT) and Lumbar Lordosis (LL) were not significantly different at any timepoint. SRS and ODI scores were similar at 2 year follow up (SRS 3.8 vs. 3.6, p=0.19, ODI 25.2 vs. 29.1, p=0.37)
Conclusions: Patients with PJK have higher C2-7 SVAs as well as higher pre and post-op differences in C2-7 SVA while maintaining similar T1S, T1S-CL, LL and PT. Further study on the factors that drive high C2-7 SVA will be important in understanding PJK.
Patient Care: The results of this study will improve patient care by alerting the surgeon that patients with postoperative increased C2C7 SVA may be at risk for future PJK and this added risk may be discussed with the patients.
Learning Objectives: By the conclusion of this session, participants should be able to: 1) identify the PJK rate in a large ASD population and 2) appreciate that patients with postoperative PJK may have elevated postoperative C2-C7 SVA