The Multicenter Osteoarthritis Study (MOST) is an ongoing longitudinal study which aims to identify novel and modifiable biomechanical factors (e.g., physical activity), bone and joint structural factors (assessed through knee MRI), and nutritional factors that are associated with the onset and progression of osteoarthritis (OA)-related knee symptoms and radiographic knee OA. A secondary aim is to understand whether risk factors for new disease differ from those for OA progression. Data collection encompassed the following investigative themes: mechanical risk factors, causes of knee symptoms and pain, and the long-term disease trajectory of knee OA.

The study enrolled 3,026 participants aged 50 to 79 years old with preexisting OA or at a high risk based on weight, knee symptoms, or a history of knee injuries or operations. Participants were recruited through community outreach campaigns in Birmingham, Alabama and Iowa City, Iowa. Approximately 15% of this cohort are African American and 60% are women. Baseline examinations began in 2003 and follow-up visits occurred at 15, 30, 60, 72, and 84 months. Each follow-up visit, with the exception of the 72-month visit, included clinical assessments and the collection of radiological data (i.e., x-ray and MRI), as well as other measures and instruments. The 72-month follow-up visit was conducted solely through telephone interviews. Biospecimens (i.e., blood and urine) were collected at baseline, 30 months, and 60 months. In 2016-2018, an additional 1,500 "New Cohort" participants with early or mild knee symptoms and x-ray findings of OA were enrolled in the study. The “New Cohort” and surviving participants without end-stage knee osteoarthritis from the “Original Cohort” completed clinic visits and telephone follow-up contacts at 144- ,152- 160- and 168-months. In 2023, MOST was awarded grant funding to continue long term follow-up.