@article {Spivak186, author = {Jeffrey M. Spivak and Jack E. Zigler and Travis Philipp and Michael Janssen and Bruce Darden and Kris Radcliff}, title = {Segmental Motion of Cervical Arthroplasty Leads to Decreased Adjacent-Level Degeneration: Analysis of the 7-Year Postoperative Results of a Multicenter Randomized Controlled Trial}, volume = {16}, number = {1}, pages = {186--193}, year = {2022}, doi = {10.14444/8187}, publisher = {International Journal of Spine Surgery}, abstract = {Background Cervical artificial disc replacement (C-ADR) has become a common and accepted surgical treatment for many patients with cervical disc degeneration/herniation and radiculopathy who have failed nonoperative treatment. Midterm follow-up studies of the original investigational device exemption trials comparing C-ADR to traditional anterior cervical discectomy and fusion (ACDF) have revealed C-ADR patients have less adjacent-level disease and fewer reoperations at 5 to 7 years. The purpose of this study was to examine the relationship of radiographic adjacent-level disease (R-ALD) with the amount of index-level segmental range of motion (ROM) in C-ADR patients using the long-term follow-up data from the ProDisc-C investigational device exemption trial.Methods This was a post hoc analysis of a 1:1 randomized controlled trial. The initial previously described Food and Drug Administration{\textendash}approved 2-year study was extended, and consenting patients in the original study were followed at annual intervals up to 7 years. Logistic regression was used to assess any progression in adjacent-level disease (ALD). Ordinal logistic regression was also used to assess the relationship between any progressive R-ALD and final flexion extension (F/E) ROM in C-ADR patients. Spearman{\textquoteright}s rank-order correlation was used when R-ALD was kept as an ordinal variable to assess the same relationship.Results At the last follow-up visit, the rate of progressive R-ALD was significantly higher in ACDF patients than in C-ADR patients. When C-ADR patients were divided into 3 groups based on final F/E ROM, those with 0{\textdegree} to 3{\textdegree} (n = 19), 4{\textdegree} to 6{\textdegree} (n = 15), and 7{\textdegree} (n = 42) of segmental motion at the index procedure level, the rate of progressive R-ALD trended significantly with final ROM (P = 0.01).Conclusions C-ADR leads to a significant decrease in R-ALD compared to ACDF. The difference in R-ALD is related to the preservation of motion at the index level and resultant preservation of kinematics and forces across the adjacent disc space.Level of Evidence 4.}, URL = {https://www.ijssurgery.com/content/16/1/186}, eprint = {https://www.ijssurgery.com/content/16/1/186.full.pdf}, journal = {International Journal of Spine Surgery} }