Functional and optimised imaging, image processing
We developed processes with two in house micro-CT scanners (Cabinet cone-beam microCT, Scanco & High-resolution peripheral quantitative CT, XTremeCT, Scanco), used for the characterisation of hard and soft tissues and whole joints. We have used both 9.4T and 3T magnetic resonance imaging systems to characterise soft tissue structures. For example in the spine, we are using these systems to capture the shape and micro-structure of vertebrae and build computer models. We have developed sequences to image the intervertebral disc and visualise the annular structures. We have developed bespoke equipment to image specimens using microCT or MRI under load for evaluating hard and soft tissue anatomy, properties and behaviour.
Subject-specific computational modelling
Multibody musculoskeletal modelling
Inverse dynamic analysis of the musculoskeletal system, which uses gait analysis data to generate predictions of forces within the joints. Collaborative studies with the LBRC and School of Sport Science to undertake biomechanical analysis of activities of daily living, and sports to determine the loading and motion within different joints of the body.
Subject-specific models from images, with direct validation process
Established protocols for building subject-specific finite element models from medical images, for evaluating biomechanics and the effects of variance in the patient population. We have developed protocols for extracting both the shape and the material property maps for vertebral bone, across multiple species. We use multiple specimens and multiple data sources for direct validation of subject-specific whole joint models, e.g. in the spine both load bearing and load sharing behaviour has been used in the validation of models of the ovine functional spinal unit, showing the importance of nonlinear fibres in the disc at high strain values.
In-silico assessment of joint replacements
In silico wear simulation
Linking finite element models with wear models to predict the wear of orthopaedic devices over millions of cycles. Our model predictions have been compared with simulator studies for some hip prosthesis bearing material combinations.
In silico characterisation of tissues and natural joints
Biphasic contact modelling
Modelling of joint contact mechanics with the inclusion of both solid and fluid effects. These methods has been applied to the natural hip joint to investigate the effect of a variety of daily activities.
Shape extraction, statistical and parametric shape characterisation
The detailed extraction of the shape of musculoskeletal tissues allows us to understand the population variation and capture that variation using principle component analysis, statistical analysis and parameterisation techniques. Development of techniques to scale and morph bony geometry within MSK models to replicate patient specific geometry. Using parametric shape modelling we showed that there are differences between male and female groups in the location of bone on the femoral neck, causing impingement in the hip joint.
Inverse methods & optimisation
Derivation of tissue properties using a computational model in parallel with experimental testing and property optimisation algorithms. We developed optimisation methods to calibrate simplified or image-based non-linear FEA models, either specific to cartilage indentation of osteochondral plugs or more generic tools for Abaqus (opti4Abq), including automatisation of post-processing of Abaqus models (postPro4Abq).