Mechanical Engineering - Theses
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ItemPost-traumatic knee osteoarthritis after anterior cruciate ligament reconstruction: Psychological, functional and biomechanical factors and the effect of a targeted brace( 2015)Post-traumatic knee osteoarthritis (OA) after anterior cruciate ligament reconstruction (ACLR) is prevalent in younger adults and has the potential to cause substantial knee-related symptoms and limit physical function. Physical and psychological impairments are likely to adversely affect quality of life and work participation. Knowledge of modifiable risk factors associated with knee OA post-ACLR has the greatest capacity to lead to new interventions that could change the natural history of knee OA. What are the modifiable factors associated with knee OA post-ACLR? Section A of this thesis describes the results of two cross-sectional studies which revealed that individuals with knee OA five to 12 years post-ACLR have worse knee confidence and greater kinesiophobia compared with individuals who have no OA five to 12 years post-ACLR. In individuals with knee OA five to 20 years post-ACLR, those with worse knee confidence have worse knee-related symptoms, poorer function, greater kinesiophobia, and poorer perceived self-efficacy and health-related quality of life. Section B of this thesis investigated knee biomechanics during walking in individuals post-ACLR. Pooled data from a systematic review revealed that, compared to healthy controls and uninjured contralateral knees, ACLR knees have abnormal knee biomechanics, particularly in the sagittal plane. Systematic review findings also revealed that the type of graft (hamstring or patellar) and time post-surgery could also influence knee biomechanics. A cross-sectional study also evaluated biomechanics in people with lateral knee OA post-ACLR. Compared to healthy controls, individuals with lateral knee OA five to 20 years post-ACLR had greater knee flexion and lower knee internal rotation angles, as well as greater pelvic anterior tilt, and hip flexion angles. Is there a potential intervention for modifiable risk factors associated with knee OA post-ACLR? A targeted knee brace was investigated for individuals with knee OA post-ACLR. First, a within-subject randomized study investigated the immediate and four-week effects of a targeted knee brace on knee-related symptoms and function in individuals with knee OA post-ACLR. The brace produced improvements in knee-related symptoms immediately and following four weeks of intervention. Second, a within-subject randomized study evaluated the immediate effects of varus bracing on gait characteristics in individuals with lateral knee OA post-ACLR. Results revealed that the unloader brace significantly altered gait characteristics associated with lateral knee OA post-ACLR. Overall, this thesis sheds light on some of the modifiable risk factors associated with knee OA post-ACLR, and investigated one targeted intervention with the potential to improve quality of life of individuals with knee OA post-ACLR. Targeting psychological, functional and biomechanical risk factors in individuals post-ACLR may aid in optimal recovery, and slowing disease progression in individuals with knee OA post-ACLR.
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ItemA computational approach to investigate subchondral bone adaptation during the development and progression of osteoarthritis( 2013)Osteoarthritis (OA) is a degenerative joint disease widespread in the general population –particularly the aged. Advanced OA is most notably characterised by the gradual degradation of the protective cartilage tissues of articulating bones that can lead to severe joint pain and immobilisation. There is emerging evidence to suggest that observable changes in the structure and material properties of underlying subchondral bone (bone directly beneath the joint’s cartilage) play critical roles in the aetiology of OA. Factors driving these subchondral bone changes are largely unknown but it is believed to occur as a response to either stabilise or accelerate OA due to altered biomechanical loads. This study quantified the extent of subchondral bone adaptation from an experiment assessing two cohorts: mice with induced knee OA by surgical destabilisation of the medial meniscus and a sham surgery group of mice without OA. Time-dependent subchondral bone adaptations were quantified using microtomography imaging techniques prior to surgery and 4, 8 and 12 weeks post-surgery. Three-dimensional finite element (FE) models were created from the baseline image data and a bone (re)modelling algorithm was developed to iteratively update the FE models, simulating subchondral bone adaptation to load. Simulations were compared with the post-surgery image data for validation, and potential osteoarthritic load changes were identified. Simulated osteoarthritic bone adaptations matched the experimental results, where localised subchondral bone density changes occurred in response to altered biomechanical loads, verifying that the simulation was a physiologically accurate model.