Clinical and Radiological Outcome of a New Total Cervical Disc Replacement Design

Christoph Mehren, MD; Franziska Heider, MD; Daniel Sauer, MD; Ralph Kothe, MD; Andreas Korge, MD; Wolfgang Hitzl, MD, PhD; Karin Wuertz-Kozak, MD, PhD

Disclosures

Spine. 2019;44(4):E202-E210. 

In This Article

Abstract and Introduction

Abstract

Study Design: A nonrandomized, prospective, and single-center clinical trial of the ProDisc Vivo prosthesis.

Objective: The aim of this study was to investigate the clinical and radiological results of a refined total cervical disc replacement (cTDR), the ProDisc Vivo, with two years of follow-up (FU). The incidence of implant-related complications was recorded as a secondary outcome variable.

Summary of Background Data: Previous generations of the ProDisc artificial cervical disc replacement generate high primary stability due to keel-based designs with opening of the anterior cortex during the implantation and subsequent high rates of heterotopic ossifications.

Methods: Clinical outcome scores included the Neck Disability Index (NDI), Visual Analogue Scale (VAS), arm and neck pain self-assessment questionnaires. The radiological outcome included the range of motion (ROM) and the occurrence of heterotopic ossifications. The incidence of implant-related complications with new implant design was recorded as a secondary outcome variable.

Results: A total of 55 patients received a single-level treatment with the ProDisc Vivo cTDR between C3/4 and C6/7, with a follow-up rate of 78%. The clinical outcome scores improved in all parameters significantly (P = 0.0001) (NDI: 68.3 → 17.4; VAS arm: 6.3 → 1.4; VAS neck: 4.9 → 1.6). The ROM of the index-segment did not show a significant change (P = 0.26) (7.9° → 9.2°). Heterotopic ossifications at the index segment was found as grade 0 in 58%, grade 1 in 22%, grade 2 in 10%, grade 3 (with functional impairment of the prosthesis) in 7%, and grade 4 in 3% of the cases. We observed three implant-related complications (5.5%), with two implant dislocations anteriorly and one low-grade infect.

Conclusion: cTDR with ProDisc Vivo demonstrated a significant and sustained improvement of all clinical outcome parameters. A less invasive implantation mechanism with lower primary stability of the cTDR might be a reason for a higher dislocation rate than the keel-based previous generation ProDisc C.

Level of Evidence: 4

Introduction

Total cervical disc replacement (cTDR) has been established as a viable treatment option for a variety of pathologies, such as symptomatic cervical disc disease or soft disc herniation with radiculopathy. Clinical studies have demonstrated this procedure to be a safe and suitable treatment alternative to the gold standard, anterior cervical discectomy and fusion (ACDF).[1–9]

Since the first introduction of cTDRs, design characteristics and material being used have undergone extensive changes. Initial designs were created with a focus on ensuring primary stability, but employed extensive fixations with screws (e.g., PrestigeST; Medtronic Sofamor Danek, Memphis, TN) or required excessive preparation of the implant site (Bryan Disc; Medtronic Sofamor Danek, Memphis, TN). These designs resulted in technically demanding, time-consuming implantation processes and bared a risk for heterotopic ossifications (HOs) due to opening of the cortical structures.[10,11] Thus, subsequent cTDR designs aimed to simplify the implantation while circumventing the need to open the cortical structures. Furthermore, surface coatings (e.g., plasma-sprayed titanium or hydroxyapatite surface modifications) were introduced to enhance bony ingrowth and thus ensure long-term fixation.[12]

The ProDisc Vivo (DePuy Synthes, West Chester, PA) consists of two titanium alloy endplates for improved MRI compatibility and a fixed, ultra-high molecular weight polyethylene (UHMWPE) core on cobalt-chrome-molybdenum alloy articulation, which provides motion in all axes in a semi-constrained fashion for flexion/extension and lateral bending. Primary stability is provided with teeth fixation at each endplate. The superior plate has a convex design for better anatomical fixation as demonstrated in Figure 1. A trapezoidal footprint design should provide optimal anatomical fit and maximum endplate coverage. Long-term stability is provided by a plasma-sprayed titanium surface, which is intended to promote secondary bony ingrowth.

Figure 1.

The ProDisc Vivo artificial disc. Available at:https://emea.depuysynthes.com.

The aim of this study was to verify the clinical effectiveness of the third design generation of the ProDisc, the ProDisc Vivo, with 2 years follow-up (FU) and to evaluate their radiologic outcome, including implant specific complications.

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