366 - The Positive Effect of Continued Motion of a Cervical Artificial Disc...

General Session: Cervical-1

Presented by: J. Spivak - View Audio/Video Presentation (Members Only)


J. Spivak(1), J. Zigler(2), M. Janssen(3), B. Darden(4), K. Radcliff(5)

(1) New York University, Orthopedic Surgery, New York, NY, United States
(2) Texas Back Institute, Plano, TX, United States
(3) Spine Education and Research Institute, Denver, CO, United States
(4) OrthoCarolina Spine Center, Charlotte, NC, United States
(5) Rothman Institute Thomas Jefferson University, Philadelphia, PA, United States


Introduction: Development of symptomatic adjacent level degeneration (ALD) following anterior cervical discectomy and fusion (ACDF) remains a clinical concern. Cervical artificial disc replacement (C-ADR) maintains motion at the surgical level, and has been demonstrated to lower the incidence of developing radiographic ALD (R-ALD) than with ACDF. The purpose of this study is to compare the rates of progressive R-ALD up to 7 years post-surgery in patients treated with ProDisc-C (Depuy Synthes Spine, Raynham, MA) C-ADR or ACDF for one-level symptomatic cervical disc disease, and to examine the effect of final long-term flexion-extension range of motion (ROM) of the C-ADR on the development of progressive R-ALD.

Methods: A prospective randomized FDA approved IDE study was conducted at 13 sites to assess the safety and effectiveness of single-level C-ADR compared to ACDF. The study included annual patient follow-up through 7 years. 209 patients were randomized and treated (106 ACDF; 103 C-ADR). All study radiographs were assessed by independent radiologists utilizing a qualitative assessment of disc degeneration at the levels adjacent to the index surgery based on the Kellgren-Lawrence radiographic grading scale. Range of motion at the index and adjacent levels were measured. Radiographic results are presented for patients at final follow-up up to 7 years postoperatively, using the last observation carried forward with a minimum 5 year follow up. The relationship between progressive R-ALD and long term ROM of the C-ADR, at the final follow-up, was also examined.

Results: Final follow-up data was available for 160 patients (87 C-ADR, 73 ACDF) Basic demographics were similar between the two patient groups. The rate of progressive R-ALD at either adjacent level was statistically significantly lower in the C-ADR cohort compared to ACDF patients (rates: 53% vs. 77% respectively (p=0.0028)). The rate of R-ALD was significantly lower only in the superior adjacent level for the C-ADR vs. ACDF patients (36% vs. 59%, p=0.0061), although R-ALD trended lower in C-ADR patients for the inferior adjacent level (C-ADR 34% vs. ACDF 43% (p=0.24)). The index level ROM of the C-ADR at final follow up was found to significantly correlate (inversely) with the degree of progressive R-ALD (p=0.0113). Discs moving 0-3 degrees had a 68% rate of progressive R-ALD, while the rate was 53% in discs moving 4-6 degrees, and 43% in discs moving 7 or more degrees (p=0.0704). Severe progression of R-ALD (grade 0-1 initially, 3-4 at follow-up) in C-ADR patients was found in 47% of patients with discs moving 0-3 degrees, in no patients with discs moving 4-6 degrees, and in 9.5% of patients with discs moving 7+ degrees (p=0.0013).

Conclusions: Long term results demonstrated that the rate of progressive radiographic adjacent level disc degeneration was significantly lower in C-ADR patients as compared to ACDF patients. The rate of radiographic ALD in the C-ADR patients was found to correlate inversely with the final ROM of the C-ADR.