Anterior Bone Loss After 2-Level Cervical Disc Arthroplasty With Baguera C Discs

Study Design: Clinical original research. Objectives: The objectives of this study were to identify the risk factors and incidence of anterior bone loss (ABL) after 2-level Baguera C cervical disc arthroplasty (CDA), as well as the impact of hybrid surgery on ABL. Background: ABL commonly occurs after CDA. Despite recent research on ABL, data on its incidence after 2-level CDA remain limited. Methods: In this retrospective cohort study, we reviewed patients who underwent 2-level Baguera C CDA in a medical center. We recorded the extent of ABL and radiologic parameters, including the segmental and global alignment angles, lordotic angle (or functional spinal unit angle), shell angle, global range of motion (ROM), and ROM of the index level. Results: We found that all patients had at least grade 1 ABL in 1 or 2 surgical segments. Of the 216 surgical segments analyzed, 66 (30.5%) had grade 2 ABL, 141 (65.3%) had grade 1 ABL, and only 9 (4.2%) had no bone loss at all. Patients with grade 2 ABL tended to have larger segmental and global alignment angles, and shell angle during extension than did those with grade 1 or grade 0 ABL. Conclusions: ABL is a common phenomenon found in essentially all patients receiving 2-level CDA. The extent and prevalence of ABL were greater in 2-level CDA than in 1-level CDA. Larger segmental and global alignment angles, and shell angle during extension were associated with grade 2 ABL, which is extensive bone loss with implant exposure. The exact mechanism of ABL remains to be elucidated.