Enabling stratification of intervertebral disc repair

Summary

PhD positions are available for one or more students to evaluate minimally invasive treatments for spinal disc degeneration using experimental and computational engineering methods. Specifically, the projects will develop novel testing methods using our new six-axis spinal simulator, developed specifically for testing soft tissue components in the human spine. The projects will involve a combination of experimental testing using the simulator and computational modelling to evaluate different potential testing regimes and the effects of patient variance.

Back pain is the leading cause of years lived with disability in the western countries, with disc degeneration the main causal diagnosis. Current surgical options have poor long-term outcomes and are highly invasive and non-reversible. There are therefore pressing needs for novel, less invasive, treatments to delay or prevent the need for more invasive options.
Emerging solutions, such as the injection of biomaterials in the intervertebral disc to alleviate effects of degeneration, have so far had a poor clinical conversion, with adverse outcomes reported in early-generation products and lack of clinical uptake. These adverse effects are partly observed because current preclinical testing methods do not include variability from patient to patient, or the types of loading known to cause device failure. Little is known about the optimum surgical delivery of these treatments or on which patient characteristics they depend.

In this PhD project, you will be able to access unique experimental and computational facilities developed through a large programme of research. You will aim to develop an experimental or computational testing process for the biomechanical assessment of biomaterials for intervertebral discs which can include patient variability. This will be used to optimise variables in biomaterial injections. The studies will include the use of Finite Element Analysis and 3D image analysis alongside in vitro testing methodologies and equipment to examine the mechanical performance of biomaterials injected into the disc and how they vary with anatomical and tissue characteristics.

You will have a background in experimental testing of materials, if possible with experience working with anatomical tissues, or in finite element analysis, if possible, with knowledge of non-linear modelling.

Background

These studentship projects are part of a large programme of multidisciplinary research on the development of novel therapies for back pain.

Using novel patented biomaterials at the University of Leeds, we have developed a robust preclinical uniaxial testing protocol for the assessment of injection of biomaterials in degenerated intervertebral disc which aim to recover disc height and mechanical behaviour. We have acquired a new 6-axis testing machine developed specifically for the spine to enable further characterisation for more types of motions. As experimental preclinical testing using either animal or cadaveric tissue is limited by the number of specimens that can be tested, it can be complemented with a computational approach to test a larger range of variables which may be critical to the outcome of treatments. These variables can be either surgical variables such as volume injected or pressure at which it is injected or specimen variables such as variation in the anatomy of intervertebral disc and surrounding structure.

This research will aim to develop a combined experimental (in vitro) and computational (in silico) testing protocol which can assess these variations. Experimental models which can simulate the extreme of motions that the spine can go through will provide practical information on the risks of failure for interventional repairs using injectable biomaterials. Computational models that simulate the specimen-specific behaviour of treated intervertebral disc present the opportunity to test new repair biomaterials for a wide range of patients, taking into account their variation in anatomy and in tissue structure.

Research objectives

In this PhD project, you will aim to develop a testing process for the biomechanical assessment of biomaterials for intervertebral discs which can include patient variability. This will be used to define optimum surgical variables for biomaterial injections.

Specific objectives will depend on your skills and preferences and can be

• The development of robust computational methodologies to evaluate mechanical performance of spinal disc treatment,
• the acquisition of robust experimental data regarding the mechanical performance of treatment using cadaveric tissue,
• the validation of computational methods based on 3D specimen-specific imaging and modelling,
• the development of population models based on machine learning methods including statistical models and on 3D image analysis,
• the identification of key patient-specific characteristics that can be used to answer clinical questions such as how much biomaterial should be injected into the intervertebral disc to restore function.

Skills and opportunities

You will have a background in experimental testing of materials, if possible with experience working with anatomical tissues, or in finite element analysis, if possible, with knowledge of non-linear modelling. During the project, you may be expected to prepare and test human cadaveric or animal tissue specimens; previous experience in handling human or animal tissue would be beneficial, but not essential.

Full training will be provided on all laboratory methods and the associated health and safety requirements.

You will learn practical aspects of project management, scientific writing for technical or non-technical dissemination, and gain presentation skills through international conferences and group meetings. You will gain specific technical skills and training in computational modelling including verification and validation aspects, 3D image analysis, experimental testing of tissues, and testing of spinal interventions as well as gaining broader experience in preclinical testing of medical devices.

Environment

In these projects, you will be able to access unique experimental and computational facilities developed through a large programme of research.

You will join the multi-disciplinary, dynamic Institute of Medical and Biological Engineering (IMBE) embedded within the School of Mechanical Engineering and the Faculty of Biological Sciences at the University of Leeds. The IMBE is a world-renowned medical engineering research centre which specialises in research and translation of medical technologies that promote ’50 active years after 50’. The team working on the spine biomechanics is currently composed of six researchers, led by three academics.

As a PhD student within IMBE, there will be opportunities to contribute to wider activities related to medical technologies including public and patient engagement, group training and social events. Groups of researchers working on aligned projects or using similar methods meet regularly to share ideas and best practice, and we encourage collegiate working. We will support your long term career ambitions through bespoke training and encourage external secondments, laboratory visits or participation at international conferences.

Applicants to research degree programmes should normally have at least a first class or an upper second class British Bachelors Honours degree (or equivalent) in an appropriate discipline. The criteria for entry for some research degrees may be higher, for example, several faculties, also require a Masters degree. Applicants are advised to check with the relevant School prior to making an application. Applicants who are uncertain about the requirements for a particular research degree are advised to contact the School or Graduate School prior to making an application.

The minimum English language entry requirement for research postgraduate research study is an IELTS of 6.0 overall with at least 5.5 in each component (reading, writing, listening and speaking) or equivalent. The test must be dated within two years of the start date of the course in order to be valid. Some schools and faculties have a higher requirement.