PT  - JOURNAL ARTICLE
AU  - Jeffrey M. Spivak
AU  - Jack E. Zigler
AU  - Travis Philipp
AU  - Michael Janssen
AU  - Bruce Darden
AU  - Kris Radcliff
TI  - Segmental Motion of Cervical Arthroplasty Leads to Decreased Adjacent-Level Degeneration: Analysis of the 7-Year Postoperative Results of a Multicenter Randomized Controlled Trial
AID  - 10.14444/8187
DP  - 2022 Feb 01
TA  - International Journal of Spine Surgery
PG  - 186--193
VI  - 16
IP  - 1
4099  - http://ijssurgery.com//content/16/1/186.short
4100  - http://ijssurgery.com//content/16/1/186.full
SO  - Int J Spine Surg2022 Feb 01; 16
AB  - 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–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’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° to 3° (n = 19), 4° to 6° (n = 15), and 7° (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.