Community Research and Development Information Service - CORDIS

Final Report Summary - SID (Spinal Implant Design)

The project trained a cohort of new researchers through a novel European Industrial Doctorate between the Department of Mechanical Engineering at the University of Birmingham (UK) and S14 Implants (France) on Spinal Implant Design (SID). The overall aim of the research training was to develop a novel European Industrial Doctorate on spinal implant design (SID) to develop next generation implants through providing research and entrepreneurial training to develop the future leaders in this vital field of bio-medical engineering.

The overall aim was achieved by undertaking the following complementary research objectives (ROs):
RO1: To design, manufacture and test a next generation lumbar disc replacement made from elastomers to better replicate the mechanical properties of the natural intervertebral disc;
RO2 To design manufacture and test a next generation cervical replacement implant for treating degeneration of the cervical intervertebral disc.

SID aimed to maximise the potential of ESRs in the area of spinal implant design. The training programme has given them the necessary skills to work in academia or industry. The specific Training Objectives (TOs) were to:
TO1: produce highly trained researchers with a range of engineering skills to develop next generation spinal implants (links to RO1 and RO2);
TO2: give the researchers a wide range of generic and transferrable skills to enable them to operate in a range of research environments;
TO3: give the researchers a wide range of entrepreneurial skills to enable them to maximise business opportunities;
TO4: provide unique training opportunities across industry and academia;
TO5: provide high quality research supervision to enable the researchers to successfully gain a PhD;
TO6: produce researchers that are capable of working both independently and as part of a multidisciplinary team;
TO7: give researchers a detailed understanding of the regulatory issues surrounding the design of spinal implants;
TO8: produce researchers with the necessary skills to communicate with a wide-range of audiences;
TO9: require each researcher to produce a Personal Career Development Plan.

The ESRs have been involved in an exciting training programme to provide them with all the engineering research skills, generic and transferable research skills, entrepreneurship skills and training for outreach activities.

A new parametric model for the lumbar spine has been developed which enables different geometries and material properties to be considered easily. A script, to automatically obtain the vertebrae of the lumbar region, has been developed and generates the geometry of five vertebrae (L1 to L5) and intervertebral discs scaled with respect to the height of a patient. Moreover, it enabled sensitivity studies to be performed to understand the influence of the vertebral geometry and material properties on the biomechanics of the spine.

A simple model of the cervical spine has been created and simulations have been performed with a device for disc replacement. The results have helped to identify the weakness of the device, and targets for its improvement. Furthermore, a subject-specific model has been developed from a model supplied by the industrial partner (S14) and a custom intervertebral disc replacement has been designed. The new topology, following the anatomical features of the patient, has been compared to the previous design and a fusion cage through FE simulations. The results are promising, showing good potential for the development in this direction.
The materials used in the posterior stabilization device (BDyn) have been characterized through mechanical testing and Finite Element analysis. The findings have been used to perform dynamic simulations, obtaining the validation against dynamic mechanical analysis (DMA). It was then possible to perform simulations in combination with the GsDyn device, understanding the influence of the BDyn dynamic components on its stress distribution.

A Matlab code has been created and validated to quantify viscoelastic properties of materials. The code has been used in the preliminary study of understanding the effect of load on viscoelastic properties. The viscoelastic properties of two grades of silicones were also examined and strain dependent glass transitions observed. The viscoelastic properties of a spinal posterior dynamic stabilisation device have been investigated and the results of this study have been published in the Journal of the Mechanical Behaviour of Biomedical Materials. A further study quantified the changes of the frequency-dependant viscoelastic properties of the posterior dynamic stabilisation device due to in vitro oxidation; this study has been published in the Journal of Biomedical Material Research Part B: Applied Biomaterials. A third study has investigated changes in viscoelastic properties due to implantation. Two further studies have investigated the effect of oxidative and hydrolytic degradation of five commercially available biomaterials.

A design of a cervical disc replacement has been modelled in SolidWorks. Potential materials for the viscoelastic element in the cervical disc replacement have been tested. A paper describing a design process of the cervical disc replacement device is currently in progress with a view of being submitted in a near future. A set of two different designs of the polyaxial pedicle screws used in fixation of the spinal posterior dynamic stabilization device have been investigated. The obtained results are going to be published in a paper that is currently under review.

New designs for a lumbar disc replacement have been developed based on meetings with several surgeons and attending surgeries. Different materials have been tested to evaluate their suitability for the implant purpose. A new project was started in collaboration with orthopaedic surgeons from the Rizzoli Orthopaedic Institute of Bologna, Italy, to develop a novel spinal implant to treat severe scoliosis in children. A novel device has been designed, manufactured and mechanically tested to characterize its behaviour under quasi-static and fatigue loads. Results have demonstrated improved mechanical performance than current marketed devices and, therefore, the clinical potential of the novel device is promising. Furthermore, its design features provide further benefits such as minimally invasive surgeries and reduced risk of infections, resulting in a safer treatment for patients and saving costs for health services.

www.birmingham.ac.uk/SID

Reported by

THE UNIVERSITY OF BIRMINGHAM
United Kingdom

Subjects

Life Sciences
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