The Open Orthopaedics Journal

ISSN: 1874-3250 ― Volume 15, 2021

The Memory Metal Spinal System in a Posterior Lumbar Interbody Fusion (PLIF) Procedure: A Prospective, Non-Comparative Study to Evaluate the Safety and Performance

D Kok1, M Grevitt2, FH Wapstra1, AG Veldhuizen*, 1
1 University Medical Center Groningen, The Netherlands
2 Nottingham University Hospitals NHS Trust, UK


Study Design:

A prospective, non-comparative study of 27 patients to evaluate the safety and performance of the Memory Metal Spinal System used in a PLIF procedure in the treatment of spondylolisthesis, symptomatic spinal stenosis or degenerative disc disease (DDD).


To evaluate the clinical performance, radiological outcome and safety of the Memory Metal Spinal System, used in a PLIF procedure, in the treatment of spondylolisthesis, symptomatic spinal stenosis or degenerative disc disease in human subjects.

Summary of Background Data:

Spinal systems that are currently available for correction of spinal deformities or degeneration such as lumbar spondylosis or degenerative disc disease, use components manufactured from stainless steel or titanium and typically comprise two spinal rods with associated connection devices. The Memory Metal Spinal System consists of a single square spinal rod made from a nickel titanium alloy (Nitinol) used in conjunction with connection devices. Nitinol is characterized by its shape memory effect and is a more flexible material than either stainless steel or titanium. With current systems there is loss of achieved reposition due to the elastic properties of the spine. By using a memory metal in this new system the expectation was that this loss of reposition would be overcome due to the metal’s inherent shape memory properties. Furthermore, we expect a higher fusion rate because of the elastic properties of the memory metal.


Twenty-seven subjects with primary diagnosis of spondylolisthesis, symptomatic spinal stenosis or degenerative disc disease (DDD) were treated with the Memory Metal Spinal System in conjunction with the Brantigan IF® Cage in two consecutive years. Clinical performance of the device was evaluated over 2 years using the Oswestry Disability Index (ODI), Short Form 36 questionnaire (SF-36) and pain visual analogue scale (VAS) scores. Safety was studied by collection of adverse events intra-operative and during the followup. Interbody fusion status was assessed using radiographs and a CT scan.


The mean pre-operative ODI score of 40.9 (±14.52) significantly improved to 17.7 (±16.76) at 24 months postoperative. Significant improvement in the physical component from the SF36 questionnaire was observed with increases from the baseline result of 42.4 to 72.7 at 24 months (p<.0001); The emotional component in the SF36 questionnaires mean scores highlighted a borderline significant increase from 56.5 to 81.7 at 24 months (p=0.0441). The average level of leg pain was reduced by more than 50% postoperation (VAS values reduced from 5.7 (±2.45) to 2.2 (±2.76) at 24 month post-operation with similar results observed for back pain. CT indicated interbody fusion rate was not significantly faster compared to other devices in literature. No device related adverse events were recorded in this study.


The Memory Metal Spinal System, different from other devices on the market with regard to material and the one rod configuration, is safe and performed very well by improving clinically important outcomes in the treatment of spondylolisthesis, symptomatic spinal stenosis or degenerative disc disease. In addition the data compares favorably to that previously reported for other devices in the literature.

Keywords: Memory metal spinal system, PLIF, spondylolisthesis, degenerative disc disease, spinal fusion.

Article Information

Identifiers and Pagination:

Year: 2012
Volume: 6
First Page: 220
Last Page: 225
Publisher Id: TOORTHJ-6-220
DOI: 10.2174/1874325001206010220

Article History:

Received Date: 9/1/2012
Revision Received Date: 3/4/2012
Acceptance Date: 3/4/2012
Electronic publication date: 15/6/2012
Collection year: 2012

© Kok et al.; Licensee Bentham Open.

open-access license: This is an open access article licensed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.

* Address correspondence to this author at the University Medical Center Groningen, The Netherlands; Tel: +31-50-3610068; Fax: +31-50-3611737; E-mail:

Track Your Manuscript:


"Open access will revolutionize 21st century knowledge work and accelerate the diffusion of ideas and evidence that support just in time learning and the evolution of thinking in a number of disciplines."

Daniel Pesut
(Indiana University School of Nursing, USA)

"It is important that students and researchers from all over the world can have easy access to relevant, high-standard and timely scientific information. This is exactly what Open Access Journals provide and this is the reason why I support this endeavor."

Jacques Descotes
(Centre Antipoison-Centre de Pharmacovigilance, France)

"Publishing research articles is the key for future scientific progress. Open Access publishing is therefore of utmost importance for wider dissemination of information, and will help serving the best interest of the scientific community."

Patrice Talaga
(UCB S.A., Belgium)

"Open access journals are a novel concept in the medical literature. They offer accessible information to a wide variety of individuals, including physicians, medical students, clinical investigators, and the general public. They are an outstanding source of medical and scientific information."

Jeffrey M. Weinberg
(St. Luke's-Roosevelt Hospital Center, USA)

"Open access journals are extremely useful for graduate students, investigators and all other interested persons to read important scientific articles and subscribe scientific journals. Indeed, the research articles span a wide range of area and of high quality. This is specially a must for researchers belonging to institutions with limited library facility and funding to subscribe scientific journals."

Debomoy K. Lahiri
(Indiana University School of Medicine, USA)

"Open access journals represent a major break-through in publishing. They provide easy access to the latest research on a wide variety of issues. Relevant and timely articles are made available in a fraction of the time taken by more conventional publishers. Articles are of uniformly high quality and written by the world's leading authorities."

Robert Looney
(Naval Postgraduate School, USA)

"Open access journals have transformed the way scientific data is published and disseminated: particularly, whilst ensuring a high quality standard and transparency in the editorial process, they have increased the access to the scientific literature by those researchers that have limited library support or that are working on small budgets."

Richard Reithinger
(Westat, USA)

"Not only do open access journals greatly improve the access to high quality information for scientists in the developing world, it also provides extra exposure for our papers."

J. Ferwerda
(University of Oxford, UK)

"Open Access 'Chemistry' Journals allow the dissemination of knowledge at your finger tips without paying for the scientific content."

Sean L. Kitson
(Almac Sciences, Northern Ireland)

"In principle, all scientific journals should have open access, as should be science itself. Open access journals are very helpful for students, researchers and the general public including people from institutions which do not have library or cannot afford to subscribe scientific journals. The articles are high standard and cover a wide area."

Hubert Wolterbeek
(Delft University of Technology, The Netherlands)

"The widest possible diffusion of information is critical for the advancement of science. In this perspective, open access journals are instrumental in fostering researches and achievements."

Alessandro Laviano
(Sapienza - University of Rome, Italy)

"Open access journals are very useful for all scientists as they can have quick information in the different fields of science."

Philippe Hernigou
(Paris University, France)

"There are many scientists who can not afford the rather expensive subscriptions to scientific journals. Open access journals offer a good alternative for free access to good quality scientific information."

Fidel Toldrá
(Instituto de Agroquimica y Tecnologia de Alimentos, Spain)

"Open access journals have become a fundamental tool for students, researchers, patients and the general public. Many people from institutions which do not have library or cannot afford to subscribe scientific journals benefit of them on a daily basis. The articles are among the best and cover most scientific areas."

M. Bendandi
(University Clinic of Navarre, Spain)

"These journals provide researchers with a platform for rapid, open access scientific communication. The articles are of high quality and broad scope."

Peter Chiba
(University of Vienna, Austria)

"Open access journals are probably one of the most important contributions to promote and diffuse science worldwide."

Jaime Sampaio
(University of Trás-os-Montes e Alto Douro, Portugal)

"Open access journals make up a new and rather revolutionary way to scientific publication. This option opens several quite interesting possibilities to disseminate openly and freely new knowledge and even to facilitate interpersonal communication among scientists."

Eduardo A. Castro
(INIFTA, Argentina)

"Open access journals are freely available online throughout the world, for you to read, download, copy, distribute, and use. The articles published in the open access journals are high quality and cover a wide range of fields."

Kenji Hashimoto
(Chiba University, Japan)

"Open Access journals offer an innovative and efficient way of publication for academics and professionals in a wide range of disciplines. The papers published are of high quality after rigorous peer review and they are Indexed in: major international databases. I read Open Access journals to keep abreast of the recent development in my field of study."

Daniel Shek
(Chinese University of Hong Kong, Hong Kong)

"It is a modern trend for publishers to establish open access journals. Researchers, faculty members, and students will be greatly benefited by the new journals of Bentham Science Publishers Ltd. in this category."

Jih Ru Hwu
(National Central University, Taiwan)

Browse Contents

Webmaster Contact:
Copyright © 2021 Bentham Open