Predicting osteoarthritis outcome through muscle tissue characteristics
My project within the KNEEMO network focuses on the predictive value of structural and physiological factors on outcome in knee osteoarthritis – specifically knee osteoarthritis progression and knee replacement risk. Knee osteoarthritis is responsible for over 600,000 knee replacements in the United States annually – a procedure driving a large portion of costs involved in managing knee osteoarthritis. The health and economic burden of knee osteoarthritis is expected to rise significantly above the current $9 billion spent annually in the United States, largely due to expanding indications for knee replacement, particularly among younger adults. Identifying predictors of knee osteoarthritis progression and ultimately knee replacement risk would be advantageous for studying targeted disease-modifying therapies as well as directing research and treatment in these patients.
The primary predictors that I am evaluating are thigh muscle strength and morphology. Specifically, for muscle strength, I am analyzing the impact of clinically assessed knee extensor and knee flexor weakness over a period of 5 years on subsequent knee replacement risk. Secondly, I am using advanced MRI techniques to evaluate knee extensor and flexor muscle cross-sectional area over a similar period prior to knee replacement. I will be collaborating with other research fellows within the KNEEMO consortium to develop an individualized model for muscle morphology assessment.
This program of research is ancillary to the Osteoarthritis Initiative (OAI), an ongoing multi-center longitudinal cohort study designed to identify biomarkers and risk factors for knee osteoarthritis incidence and progression (http://www.oai.ucsf.edu/). As part of the OAI, participants aged between 45 and 79 years with, or at risk of, symptomatic knee osteoarthritis in at least one knee were recruited at four centers in the United States. OAI participants were examined annually over four years using imaging and clinical outcomes, which included specific questions in regard to receiving a knee replacement in the preceding 12 months. Knee replacement was confirmed by radiography, or from hospital records when radiographs were not available.
Impact and Dissemination
Importantly, muscle weakness is amenable to non-pharmacological intervention. Identifying muscle weakness as a risk factor for knee osteoarthritis progression and knee replacement risk, independent of radiographic severity, may thus provide avenues to modify risk of knee osteoarthritis progression and replacement surgery.