Sagittal alignment differences on the operating room table compared to preoperative and postoperative imaging in anterior cervical discectomy and fusion.

Study Design: The study design used was a retrospective cohort.

Objective: The objective of this study is to determine if intraoperative improvements in sagittal alignment on the operating table persisted on postoperative standing radiographs.

Summary Of Background Data: Cervical sagittal alignment may be correlated to postoperative outcomes. Since anterior cervical discectomy and fusions (ACDFs) can restore some cervical lordosis through intervertebral grafts/cages, it is important to understand if intraoperative radiographic measurements correlate with persistent postoperative radiographic changes.

Materials And Methods: Patients undergoing elective primary ACDF were screened for the presence of lateral cervical radiographs preoperatively, intraoperatively, and postoperatively. Patients were excluded if their first postoperative radiograph was more than 3 months following the procedure or if cervical lordosis was not able to be measured at each time point. Paired -tests were utilized to compare differences in measurements between time points. Statistical significance was set at < 0.05.

Results: Of 46 included patients, 26 (56.5%) were female, and the mean age was 55.2 ± 11.6 years. C0-C2 lordosis significantly increased from the preoperative to intraoperative time point (delta [Δ] = 4.49, = 0.029) and significantly decreased from the intraoperative to postoperative time period (Δ = -6.57, < 0.001), but this resulted in no significant preoperative to postoperative change (Δ = -2.08, = 0.096). C2 slope decreased from the preoperative to the intraoperative time point (Δ = -3.84, = 0.043) and significantly increased from the intraoperative to the postoperative time point (Δ = 3.68, = 0.047), which also resulted in no net change in alignment between the preoperative and postoperative periods (Δ = -0.16, = 0.848). There was no significant difference in the C2-C7 SVA from the preoperative to intraoperative (Δ = 0.85, = 0.724) or intraoperative to postoperative periods (Δ = 2.04, = 0.401); however, the C2-C7 SVA significantly increased from the preoperative to postoperative period (Δ = 2.88, = 0.006).

Conclusions: Intraoperative positioning predominantly affects the mobile upper cervical spine, particularly C0-C2 lordosis and C2 slope, but these changes do not persist postoperatively.