341 - Adjacent Level Radiographic Degenerative Changes Following Single Leve...

#341 Adjacent Level Radiographic Degenerative Changes Following Single Level Artificial Disc Replacement or ACDF at 5-7 Year Follow-up

Oral Posters: Cervical

Presented by: J. Spivak

Author(s):

J.M. Spivak (1)
R.B. Delamarter (2)
D.B. Murrey (3)
J.E. Zigler (4)
M. Janssen (5)
J.A. Goldstein (1)

(1) New York University Hospital for Joint Diseases, New York, NY, USA
(2) Cedars-Sinai Spine Center, Santa Monica, CA, USA
(3) OrthoCarolina Spine Center, Charlotte, NC, USA
(4) Texas Back Institute, Plano, TX, USA
(5) Center for Spinal Disorders, Denver, CO, USA

Abstract

Purpose: Development of adjacent level degeneration (ALD) following anterior cervical discectomy and fusion (ACDF) is well described. Cervical artificial disc replacement (C-ADR) is a newer alternative surgical treatment which maintains motion at the surgical level, and may result in a lower incidence of ALD than currently seen following ACDF. The purpose of our study was to compare the radiographic rates of progressive adjacent level degeneration at 5-7 years post-surgery in patients treated with ProDisc-C (Synthes Spine, West Chester, PA), or ACDF for one-level symptomatic cervical disc disease between C3 and C7, and to examine the correlation of segmental range of motion (ROM) with the development of 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. Following enrollment in the randomized study, a continued access (CA) nonrandomized C-ADR arm was added with the same inclusion/exclusion criteria and follow up. 209 patients were randomized and treated (106 ACDF; 103 C-ADR), and an additional 136 patients were treated with C-ADR in the CA group. All radiographs were assessed by independent radiologists utilizing a qualitative assessment of disc degeneration at adjacent levels based on the Kellgren-Lawrence system (0-4 scale). Range of motion at the index and adjacent levels were also measured. Radiographic results are presented for patients with 5-7 year follow-up data. Progression in ALD, and ROM, at the latest follow-up was assessed.

Results: In the ongoing study, 5-7 year follow-up data was available for 148 randomized patients (80 C-ADR, 68 ACDF) and 56 CA C-ADR patients. Basic demographics were similar between the two randomized patient groups. The rate of progressive ALD seen on radiographs at either adjacent level (worse case) at 5-7 years was statistically significantly lower in the C-ADR cohort compared to ACDF patients (rates: 48% vs. 78% respectively (p< 0.0001), and 41% for CA C-ADR patients). The rate of ALD was significantly lower in the superior adjacent level for the C-ADR vs. ACDF patients (32% vs. 58%, p=0.0025, 25% for CA patients). ALD was also lower, but not statistically significant, in C-ADR patients for the inferior adjacent level (randomized C-ADR 31% vs. ACDF 44% (p=0.1539); CA C-ADR 31%). Average ROM was maintained in the C-ADR patients at the index and adjacent levels as compared to the preoperative values, and was significantly reduced at the index level, significantly increased at the superior level (10.1 to 11.3 degrees, p=0.0233) and increased at the inferior level (9.6 to 11.1 degrees, p=0.0876 approaching statistical significance) for the ACDF patients.

Conclusions: 5-7 year results demonstrated that the rate of radiographic adjacent level progressive disc degeneration was significantly lower in both randomized and non-randomized C-ADR patients as compared to ACDF patients. This higher rate of radiographic ALD in the fusion patients is associated with an increase in adjacent segment range of motion.

FDA Device Status: ProDisc-C approved.