[Artificial Disc Replacement] Preclinical and clinical experience with a viscoelastic total disc replacement

[Justin]

International Journal of Spine Surgery (SAS Journal)
Volume 5, Issue 4 , Pages 97-107, December 2011

Preclinical and clinical experience with a viscoelastic total disc replacement

Burkhard Rischke, MD, PhD; Raymond S. Ross, MD; Boris A. Jollenbeck, MD; Kari B. Zimmers, BS; Neal D. Defibaugh, BS; © 2011 Elsevier Inc. All rights reserved.

Background

The purpose of this study is to describe the mechanical durability and the clinical and radiographic outcomes of a viscoelastic total disc replacement (VTDR). The human intervertebral disc is a complex, viscoelastic structure, permitting and constraining motion in 3 axes, thus providing stability. The ideal disc replacement should be viscoelastic and deformable in all directions, and it should restore disc height and angle.

Methods

Mechanical testing was conducted to validate the durability of the VTDR, and a clinical study was conducted to evaluate safety and performance. Fifty patients with single-level, symptomatic lumbar degenerative disc disease at L4-5 or L5-S1 were enrolled in a clinical trial at 3 European sites. Patients were assessed clinically and radiographically for 2 years by the Oswestry Disability Index (ODI), a visual analog scale (VAS), and independent radiographic analyses.

Results

The VTDR showed a fatigue life in excess of 50 million cycles (50-year equivalent) and a physiologically appropriate level of stiffness, motion, geometry, and viscoelasticity. We enrolled 28 men and 22 women in the clinical study, with a mean age of 40 years. Independent quantitative radiographic assessment indicated that the VTDR restored and maintained disc height and lordosis while providing physiologic motion. Mean ODI scores decreased from 48% preoperatively to 23% at 2 years' follow-up. Mean VAS low-back pain scores decreased from 7.1 cm to 2.9 cm. Median scores indicated that half of the patient population had ODI scores below 10% and VAS low-back pain scores below 0.95 cm at 2 years.

Conclusions

The VTDR has excellent durability and performs clinically and radiographically as intended for the treatment of symptomatic lumbar degenerative disc disease.

Clinical Relevance

The VTDR is intended to restore healthy anatomic properties and stability characteristics to the spinal segment. This study is the first to evaluate a VTDR in a 50-patient, multicenter European study.

[laid up doc]

i presume they are speaking of the M6? i'm not aware of the Freedom being used over there...

[ajj1001]

Wonder if this about the freedom, one of the authors is my ADR surgeon who I know was involved in the freedom trial ( pretty sure he's had nothing to do with the M6). I know he was involved in research about a replacement core as well.

[Justin]

The publication above is on the Freedom^® Lumbar Disc by AxioMed. Here's a link to the full-text publication with pictures: click here.