Abstract
This thesis examines the clinical and biomechanical outcomes following a structured education and exercise therapy intervention for knee osteoarthritis (OA). It explores mechanisms explaining the clinical benefits and aims to identify patient characteristics that may influence individual responses to exercise therapy.Randomised controlled trials consistently show that exercise therapy provides moderate clinical benefits for pain and function in individuals with knee OA. However, its effectiveness has been questioned, with claims that these benefits may have been over-emphasised. Since randomised controlled trials may not reflect individual variability in responses, it is important to understand who may benefit the most. To date, few patient characteristics have been identified as related to an individual’s responses. Improving our understanding of the different responses to exercise therapy can improve clinical decision-making and guide treatment and surgical planning.
Understanding the mechanisms underlying exercise therapy effectiveness could lead to more targeted interventions. One proposed mechanism is a reduction in knee joint loads. However, current evidence suggests that the most common measure of knee joint load, the knee adduction moment (KAM), does not decrease following exercise therapy despite clinical improvements. Our literature review identified key gaps in biomechanical studies, with most focusing on KAM rather than measures like the Knee Flexion Moment (KFM), evaluating walking rather than more demanding tasks, and including only those with medial knee OA.
This thesis is structured around four related studies. The first, a systematic review, aimed to identify patient characteristics associated with responses following a combined OA education, weight management, and exercise therapy intervention for knee OA. It focused on five clinically relevant factors: age, sex, body mass index (BMI), imaging severity, comorbidities and depression. Although these are known predictors of OA progression, they are rarely studied as predictors of non-surgical interventions. The review found no evidence that older age, higher body mass index, more severe OA, presence of depression or comorbidities were associated with poorer pain or functional outcomes. Body weight and radiological severity were further explored in studies three and four. These factors were selected because clinicians and patients with knee OA often assume that higher body weight or greater OA severity predicts poorer responses.
The second study developed a statistical modelling approach necessary for estimating OA severity from radiological assessments for studies three and four. Studies three and four used a pre-post test design, including thirty-three participants who completed the Good Life with osteoArthritis: Denmark (GLA:D®) intervention. Study three assessed the relationships between radiological compartment severity, body weight and responses. It was found that a person’s body weight had little influence on pain or functional outcomes. However, greater medial compartment knee OA was related to poorer responses, while similar improvements were observed across all levels of lateral compartment knee OA. Greater patellofemoral (PF) compartment knee OA was related to larger improvements in pain and KOOS-12 scores. Study four examined whether KAM and KFM decreased following GLA:D® and whether changes were influenced by OA compartment severity or body weight during walking and chair-rise tasks. GLA:D® had minimal impact on KAM during walking, regardless of compartment severity. Larger reductions in KAM and KFM were observed during the more demanding task of chair-rise. Greater lateral and PF compartment severity was related to larger KFM reductions during both tasks. Weak relationships were found between body weight and KAM/KFM. Heavier individuals showed larger increases in KAM during walking, but this finding was uncertain.
Exercise therapy does not appear to reduce KAM during walking, despite the clinical improvements. Reductions in KAM and KFM were evident during chair-rise, particularly in those with greater lateral and PF compartment severity. The clinical implications of our findings remain unclear, as only one previous study has evaluated chair-rise following exercise therapy. Reducing KFM may be beneficial, as like KAM, it has been linked to OA progression during walking. Future research should shift the focus from KAM alone to include KFM and assess more demanding tasks such as chair-rise.
Despite concerns about its effectiveness and limited understanding of its mechanisms, exercise therapy remains integral to knee OA management. Identifying characteristics related to individual responses remains challenging. Our research found that body weight had little impact on outcomes, while greater severity in the medial compartment was related to poorer responses. Clinicians can be reassured that most patients will experience meaningful improvements in pain and function. Given challenges in engaging patients in first-line interventions, all individuals with knee OA should be encouraged to undertake exercise therapy, education, and weight management before considering joint replacement surgery.
| Date of Award | 2025 |
|---|---|
| Original language | English |
| Supervisor | Nick BROWN (Supervisor), Joseph Lynch (Supervisor), Andrew WOODWARD (Supervisor) & Jennie SCARVELL (Supervisor) |