Biomechanical evaluation of intervertebral disc therapies

Eight out of ten adults experience back pain during their lifetimes, with many going on to have further, more severe episodes. Degeneration of the intervertebral discs is one of the most common causes. The discs are the soft tissues between the vertebrae that allow the spine to articulate. A number of medical devices and therapies have been developed for the treatment of disc degeneration, but most have failed to be successfully translated, due in part to the difficulty in testing and optimising the treatments before they reach clinical trial. The aim of this project is to develop preclinical testing methods for examining the mechanical performance of intervertebral disc treatments in a cadaveric model in vitro, and apply the methods to examine a new nucleus augmentation material that has been developed at Leeds.
The intervertebral disc tissue is challenging to examine in vitro due to its behaviour being highly dependent on the level of hydration; the behaviour under cyclic loading is seen to continue to change over many thousands of cycles. There are further engineering challenges in mechanically assessing the performance of disc treatments in vitro due to the large variation from specimen to specimen, and the difficulties in regulating the treatment itself, which often involved the injection of a material into the nucleus of the disc. This project will investigate means to control the hydration and extract mechanically comparable results in reasonable timeframes, for example by studying if short term cyclic loading can be a predictor of longer term performance. Methods to characterise the variance of the tissue and control the treatment procedure will also be developed so that the performance of different specimens can be robustly compared. The methods developed will be applied to examine the performance of a nucleus augmentation hydrogel developed at Leeds, using data from a parallel in vivo study for validation.
The methods developed in this study will provide a new suite of preclinical testing that can be used to examine a range of intervertebral disc devices and to optimise their performance before they reach animal or clinical trials. The characterisation methods will also provide information on the patient characteristics for which the treatment is best suited and any contra-indications. This will help accelerate the successful translation of new treatments and benefit healthcare providers and patients.