Physiotherapy - Theses
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ItemNeuromuscular and biomechanical factors in people following partial meniscectomy( 2014)Arthroscopic partial meniscectomy (APM) is a common surgical procedure for meniscal tears and knee osteoarthritis (OA) is often reported in people who have undergone an APM. Knee OA is a major public health problem worldwide causing pain and disability, for which there is currently no cure. Cross-sectional data suggest that people following APM have a higher knee adduction moment (KAM, an indicator of medial to lateral knee load distribution) during gait, as well as reduced knee extensor muscle strength compared to healthy controls. These factors are potential contributors to knee OA and are potentially modifiable with appropriately targeted treatments. However, prospective studies are needed to identify if these modifiable risk factors contribute to the development of structural changes to knee joint cartilage in this group. Moreover, interventions that target identified modifiable risk factors for knee OA in people following APM are urgently required to combat the individual and societal burden of the disease. Part I of this thesis describes analyses from a prospective longitudinal study that included 82 people assessed 3 months following medial APM and re-assessed 2 years later (n=66). A comparison control group of 38 healthy participants was also assessed at baseline and 2 years (n=23). Exploratory analyses revealed that the APM cohort had a higher KAM during gait and weaker knee extensor and flexor muscle strength compared to controls at 3 months following surgery. However, knee muscle strength improved in the APM cohort over time, such that no differences in strength were found 2 years later compared to controls. Peak KAM increased in the APM leg over 2 years, although this change in KAM over time was not significantly different to that seen in controls. An investigation into the mechanisms that might explain the increase in peak KAM following APM was performed. Results indicated that an increased varus position of the tibia during gait partially explained the 2-year increase in peak KAM in people following APM. Further analyses found no evidence to suggest that knee muscle weakness at 3 months predicted 2-year change in KAM. Part I also evaluated whether alterations in the KAM and knee extensor strength were associated with measures of knee joint structural change (cartilage defects and cartilage volume). These analyses demonstrated that in people 3 months following APM, a higher peak KAM during fast pace walking, but not knee muscle strength, was associated with medial tibiofemoral cartilage defect onset or deterioriation over the subsequent 2 years. Part II of this thesis describes a single-blind randomised controlled trial conducted to evaluate the effects of a specific neuromuscular exercise program (‘ALIGN’) on the peak KAM during gait and a one-leg sit-to-stand task in 62 people who had undergone APM 3-12 months earlier. Secondary outcome measures included peak KAM during fast pace gait, one-leg hop for distance, peak KAM impulse during one-leg sit-to-stand task, knee and hip muscle strength, objective measures of physical function and self-reported measures of physical function and symptoms. Findings showed that the neuromuscular exercise program did not significantly change the peak KAM during gait or a one-leg sit-to-stand task. No between-group differences were found for any of the secondary outcomes. Overall, this thesis provides some evidence to suggest that a higher peak KAM during gait may be related to knee cartilage degradation over time following APM. Interventions that aim to improve varus malalignment of the tibia could potentially delay or prevent structural changes to knee joint cartilage following APM. However, the neuromuscular exercises included in this research did not reduce the KAM during gait or a one-leg sit-to-stand task. Nevertheless, we did not quantify structural change in this study; we therefore cannot conclude that neuromuscular exercise fails to delay or prevent osteoarthritic structural change in APM patients.