Physiotherapy - Theses
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ItemEvaluating the effect of self-management interventions on medial tibiofemoral contact force using electromyogram-informed neuromusculoskeletal modelling in people at risk of, and with, established knee osteoarthritis( 2022)Knee osteoarthritis (OA) predominantly involving the medial tibiofemoral compartment is a major public health problem worldwide causing pain, disability, and reduced quality of life. Longitudinal data suggest that higher knee loads during walking are associated with structural disease progression in people with medial knee OA. Higher knee loads during walking are also associated with structural disease onset in high-risk groups such as people who have undergone arthroscopic partial meniscectomy (APM). As there is no cure for OA, conservative interventions such as strengthening exercise and “appropriate” footwear are recommended throughout the OA disease continuum. However, no studies have been able to demonstrate that exercise can reduce knee loads in those at risk of, and with, established knee OA and belief that exercise could generate harmful knee loads continues to exist among patients and clinicians. This ambiguity also extends to footwear interventions, where stable supportive shoe types are recommended in most clinical guidelines despite conflicting biomechanical evidence that suggests flat flexible shoe types may reduce knee loads. A critical limitation of the current body of evidence is the use of the external knee adduction moment (KAM) as a surrogate measure of internal medial tibiofemoral contact force (MTCF). Change in the MTCF does not necessarily correspond directly with change in the KAM, predominantly due to the role internal muscle forces play in stabilizing the knee against these external loads. The use of electromyogram (EMG)-informed neuromusculoskeletal modelling is a promising means to consider the influence of muscle in estimates of internal contact force. However, it has not yet been implemented to estimate loads in knee OA intervention studies. The overarching aim of this thesis is to implement EMG-informed neuromusculoskeletal modelling to estimate MTCF during exercise and footwear interventions in people following APM (high-risk for developing knee OA), and those with established medial knee OA. This thesis first describes secondary analyses from two randomised controlled trials. In Study 1 (Chapter 4), which involved 41 participants aged between 30-50 years with medial APM in the prior 3-12 months, no significant difference in MTCF (peak and impulse) was found following a 12-week functional weightbearing exercise program compared to no intervention. In Study 2 (Chapter 5), which involved 62 participants aged over 50 with medial knee OA and varus malalignment, no significant difference in MTCF (peak or impulse) was found between a 12-week functional weightbearing (WB) and a 12-week non-weightbearing (NWB) quadriceps strengthening exercise program. Interestingly, the functional WB exercise program reduced the external contribution to MTCF, while the NWB quadriceps strengthening program reduced the muscle contribution to MTCF. This thesis then describes two cross-sectional studies, both utilising the same cohort of 28 people over the age of 50 with medial knee OA and varus malalignment. The first (Study 3, Chapter 6) compared the immediate effect of stable supportive and flat flexible shoes on continuous and discrete measures of MTCF during walking. Statistical parametric mapping (SPM) showed lower MTCF in the stable supportive compared to flat flexible shoes during 5-18% of stance phase. For the discrete outcomes, loading impulse, mean loading rate, and max loading rate were lower in stable supportive shoes compared to flat flexible shoes. The second cross-sectional study (Study 4, Chapter 7) evaluated the MTCF and muscle forces during each of three weightbearing exercises (double leg squat, forward lunge, and single-leg heel raise), relative to walking. Results showed that knee extensor and flexor force was higher during squatting and lunging compared to walking, while the MTCF was lower during squatting and heel raises compared to walking. Collectively, this thesis does not provide any evidence that 12-week functional weightbearing exercise programs can change MTCF in people following APM and with medial knee OA and varus malalignment. However, novel findings suggest that stable supportive shoes can reduce aspects of the MTCF compared to flat flexible shoes, suggesting that this shoe type may be most suitable for people with knee OA and varus malalignment. This thesis also provides evidence that common weightbearing exercises (squatting, lunging and heel raises) do not result in harmful increases in MTCF. These exercises may therefore be used safely in clinical settings for people with knee OA and varus malalignment.