Allograft Subsidence Decreases Postoperative Segmental Lordosis With Minimal Effect on Global Alignment Following ACDF. Issue 8 (October 2022)

• Record Type: Journal Article
• Authors: Pinter, Zachariah W.; Mikula, Anthony; Shirley, Matthew; Xiong, Ashley; Wagner, Scott; Elder, Benjamin D.; Freedman, Brett A.; Nassr, Ahmad; Bydon, Mohamad; Currier, Bradford; Kaye, I. David; Kepler, Christopher; Sebastian, Arjun S.
• Is Part Of: Global spine journal. Volume 12:Issue 8(2022)
• Page Start: 1723
• Page End: 1730
• Publication Date: 2022-10
• Subjects: subsidence -- cervical alignment -- segmental lordosis -- interbody -- allograft; Spine -- Diseases -- Periodicals; Spine -- Diseases -- Treatment -- Periodicals; Spine -- Abnormalities -- Periodicals; Spine -- Surgery -- Periodicals; 616.73
• DOI: 10.1177/2192568220988270
• Languages: English
• ISSNs: 2192-5682

Abstract

Study Design: Retrospective cohort study. Objective: Studies investigating the impact of interbody subsidence in ACDF suggest a correlation between subsidence and worse radiographic and patient-reported outcomes. The purpose of this study was to assess whether allograft subsidence assessed on CT is associated with worse cervical alignment. Methods: We performed a retrospective review of a prospective cohort of patients undergoing 1 to 3 level ACDF. Cervical alignment was assessed on standing radiographs performed preoperatively, less than 2 months postoperatively, and greater than 6 months postoperatively. Allograft subsidence was assessed on CT scan performed at least 6 months postoperatively. Patients with at least 1 level demonstrating greater than 4mm of cage subsidence were classified as severe subsidence. Student's t-test was used to compare all means between groups. Results: We identified 66 patients for inclusion, including 56 patients with non-severe subsidence and 10 patients with severe subsidence. For the entire cohort, there was a significant increase in C2-7 Lordosis (p = 0.005) and Segmental Lordosis (p < 0.00 001) from preoperative to early postoperative. On comparison of severely and non-severely subsided levels, severely subsided levels demonstrated a significantly greater loss of segmental lordosis from early to mid-term follow-up than non-severely subsided levels (-4.89 versus -2.59 degrees, p < 0.0001), manifesting as a significantly lower segmental lordosis at >6 months postoperative (0.54 versus 3.82 degrees, p < 0.00 001). There were no significant differences in global cervical alignment parameters between patients with severe and non-severe subsidence. Conclusions: Severe subsidence is associated with a significant increase in loss of segmental lordosis, but has minimal effect on global cervical alignment parameters.