Realisation of the use of computational model as part of TKA surgical planning

Author: Willy Theodore

Theodore, Willy, 2019 Realisation of the use of computational model as part of TKA surgical planning, Flinders University, College of Science and Engineering

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Total Knee Arthroplasty (TKA), despite being a highly successful medical operation when measured in terms longevity, has a recurrent problem of patient dissatisfaction and complications in the range of 15-20%. Patient satisfaction is known to be a complex multifactorial issue with factors such as implant component position, pain relief, functionality or stability after surgery, patient expectation, other co-morbidities, experience of healthcare delivery. These factors can be largely grouped into surgical factors, patient factors and patient management factors. With the extensive variation between patients, clinicians need tools to help them triage patients, helping them make decision what resources needed to treat individual patient to achieve the best possible outcome for the patient while minimizing the healthcare cost. Surgical planning is one key aspect that can help clinicians better choose options for surgery.

Joint dynamics has been shown to influence clinical outcomes and is a result of complex interactions between the implant component design, component alignment, and patient specific anatomic characteristics. The relationship between these factors is not well understood and computational modelling is a scalable technique compared to other functional techniques that allow the study of both surgical and patient factors impact on joint dynamics following TKA. A computational model needs to have the right balance between complexity and practicality to be used in clinical setting.

This thesis presented a series of studies towards the development of a low-cost knee computational model that could be used to predict the clinical outcome of TKA on knee dynamics in clinical setting. The first half of this thesis discussed the development and validation technique used for the model. New registration techniques were developed to ensure the definition of reference frames between in-vitro and in-silico environment during validation is consistent. This was often overlooked in previous computational model validation studies. The computational model developed was able to complete a simulation cycle within few minutes while achieving great agreement with experimental data.

The second half of this thesis explored new non-invasive techniques to incorporate subject specific ligament properties into the developed model. Stress radiographs were used as surrogate of the load-displacement response of the knee and ligament properties were optimized to match the response. A wide variation in optimized parameters between subjects and ligaments were seen however its effects to the model dynamics is not yet well understood.

Lastly, this thesis discussed the work involved in realising the use of developed computational model as medical device. The low-cost knee computational model developed in this thesis was successfully registered as medical device and has been used in clinical setting. The model has been used to analyse approximately 1,800 post-operative complications and over 3,000 TKA pre-operative planning. In conclusion, with the right balance between complexity and practicality, it is possible to use computational modelling as part of TKA surgical planning.

Keywords: Computational modelling, TKA kinematics, surgical planning, model validation

Subject: Engineering thesis

Thesis type: Doctor of Philosophy
Completed: 2019
School: College of Science and Engineering
Supervisor: Prof Mark Taylor