Document Type

Conference Proceeding

Publication Date

12-2025

Publication Title

53rd Annual Meeting of the Cervical Spine Research Society Abstract Book

Abstract

Introduction: While favorable outcomes have consistently been reported following treatment of disc degeneration with cervical total disc replacement (cTDR), the development of heterotopic ossification (HO) at the index level has been reported. This study evaluated baseline characteristics potentially associated with the development of HO, as well as the impact of HO on 5-year clinical outcomes Materials and Methods: Baseline characteristics and 5-year outcomes of two-level polyetheretherketone (PEEK)-on-ceramic cTDR patients were stratified by worst HO grade at either index level through 5 years (defined as grade 1, 2, 3 or 4 on the McAfee/Mehren scale). Baseline index-level radiographic variables were stratified by HO grade of the corresponding level. Data were obtained from the prospective Food and Drug Administration (FDA) Investigational Device Exemption (IDE) trial for the two-level Simplify® Cervical Artificial Disc (NuVasive Inc., San Deigo, CA) Of 181 patients enrolled, 144 had radiographic data available at 5 years. All patients were treated at two contiguous levels for cervical disc degeneration with symptoms of radiculopathy and/or myelopathy. Clinical outcomes included neck disability index (NDI), neck and arm pain intensity (10-point scales), SF-36 physical component score (PCS), neurologic status, adverse event (AE) rate, and index-level reoperation (ILR) rate. Data were analyzed using a general linear model with pairwise post-hoc testing using Tukey and Fisher’s exact tests for continuous and categorical data, respectively. Change in neurologic status from baseline to 5 years was adjudicated as either improved, stable, or deteriorated; this status was evaluated against 5-year HO grade. All radiographic assessments were evaluated by an independent lab specializing in image assessment. Results: Of 144 patients assessed at 5 years, HO was grade 1 in 4 patients (2.8%), grade 2 in 95 (66.0%), grade 3 in 26 (18.1%), and grade 4 in 19 (13.2%) Of baseline variables reviewed, only inferior index level disc angle had a statistically significant effect on HO grade (p=0.04) Mean disc angle at the inferior index level was 4.0° (grade 1), 3.4° (grade 2), 2.4° (grade 3), and 0.5° (grade 4). There were no statistically significant differences seen for the other baseline variables reviewed (i.e., age, race, BMI, global ROM, index-level ROM, spondylolisthesis, translation, and anterior, posterior, and average disc heights). Of 60-month clinical outcomes reviewed, no statistically significant differences were noted based on HO grade, including NDI, neck pain, arm pain, SF-36 PCS, AE rate, and ILR rate (all, p>0.05). Neurologic status at 60 months as compared to baseline was determined to be “deteriorated” in 2 patients; both had an HO grade of 2 at both index levels at 60 months Conclusion: This study found that patients treated with PEEK-on-ceramic cTDR at two levels demonstrated comparable clinical outcomes at 5 years regardless of their worst HO grade Baseline disc angle (at the inferior index level only) was a significant factor for HO grade, with lower disc angles observed in patients developing higher HO grades. These results provide additional information to clinicians regarding the clinical impact of HO and provide further support that HO is a radiographic finding and not a clinical finding.

First Page

137

Comments

53rd Annual Meeting of the Cervical Spine Research Society, December 3-6, 2025, Washington, DC.

Last Page

138

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