Summary: | The knee joint is the most common joint affected by osteoarthritis (OA). The medial compartment of the knee is more commonly afflicted with OA than the lateral compartment. Lateral wedge insoles (LWI), a common treatment approach for the conservative management of medial compartment knee OA, have previously been considered effective in reducing external knee adduction moment (EKAM). LWI aim to shift a proportion of knee load from the medial compartment to the lateral compartment of the knee joint, providing some symptomatic relief. Foot posture may influence the efficacy of LWI in reducing the EKAM due to its effect on the dynamic function and mechanical alignment of the lower limbs. This thesis investigated the role of foot posture on the magnitude of EKAM and impact on the effectiveness of LWI for the treatment of medial compartment knee OA. Firstly, a repeatability trial was conducted to ensure investigator competency, and reliability of the methods and outcome measures utilised. Secondly, a trial using healthy subjects assessed rearfoot posture using the Foot Posture Index (FPI) to determine if a relationship existed between static foot posture and biomechanical rearfoot motion and their effects on EKAM when wearing LWI, to determine whether clinical foot parameters have a role in the magnitude of EKAM. The role of foot posture in response to LWI, the effects of foot posture on the efficacy of LWI, and effects and impact on EKAM in patients with medial compartment knee OA were assessed. No relationship was identified between clinical static foot posture, biomechanical rearfoot motion, and EKAM. However, a relationship existed between rearfoot motion and EKAM. Rearfoot range of motion can therefore predict the response to LWI. The thesis then examined research questions in regards to the collection of rearfoot motion using different methods (a heel cup cluster and a heel pin cluster) demonstrating that heel pin cluster marker sets are an acceptable method of determining rearfoot motion in barefoot and shod walking. Due to changes in walking speed with lateral wedge insoles the role of increased walking speed on the magnitude of EKAM when wearing LWI was assessed. Increasing walking speed with LWI reduced biomechanical response. The thesis has demonstrated a further understanding of foot posture and ankle motion in healthy subjects and in individuals with medial compartment knee OA. Further clinical studies investigating the role of rearfoot motion and biomechanical response to lateral wedge insoles are indicated.
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