Analysis of the nonsymptomatic incidence cohort of the Osteoarthritis Initiative in relation to physical activity: Cartilage T2 of the patella and focal knee pathology derived from 3 tesla MRI

Christoph Stehling, Hans Liebl, John A. Lynch, Roland Krug, Nancy E. Lane, Sharmila Majumdar, Thomas M. Link

The Osteoarthritis Initiative (OAI) cohort study is a multicenter, longitudinal, observational study focusing primarily on knee osteoarthritis. The study will create a public archive of data, biological samples and joint images collected over time from a very well clinically characterized population of individuals comprising two subgroups: (1) those with clinically significant knee osteoarthritis who are at risk of disease progression; and (2) individuals who are at high risk of initiation of clinically significant knee osteoarthritis. As originally designed, up to 5,000 age-eligible women and men will be recruited and enrolled at four recruitment centers: the University of Maryland School of Medicine (Baltimore), the Ohio State University (Columbus), the University of Pittsburgh, and the Memorial Hospital of Rhode Island (Pawtucket). The OAI consortium includes public funding from the National Institutes of Health and private funding from several pharmaceutical company partners managed by the Foundation for the National Institutes of Health.

The goals of our study are the following:
(1) To assess the prevalence of cartilage abnormalities, meniscus, bone marrow, and ligamentous lesions in middle-aged patients (45-55 years) with high and low levels of physical activity and no clinical symptoms of pain.
(2) To correlate patella cartilage T2 with focal cartilage, meniscus and ligamentous pathology on 3 Tesla magnetic resonance examinations of the knee, as well as physical activity level.

Patients from the incidence cohort of the OAI with an age range of 45-55 years, BMI from 19-27 and no clinical symptoms of pain assessed with the Western Ontario and McMasters (WOMAC) pain score (WOMAC pain score of 0) will be included. Two hundred patients will be examined, 100 women, and 100 men, with each group divided into two subgroups: 50 patients with high activity level (strenuous sports) and 50 patients with low activity level, based on the Physical Activity Scale for the Elderly (PASE).

Sagittal 3-D dual echo steady state (DESS), water excitation (WE) and sagittal intermediateweighted fat saturated fast spin echo, coronal T1 3-D fast low angle shot (FLASH) WE, sagittal T2 maps of the knee and axial T1 fast spin echo of the quadriceps region will be analyzed by two radiologists. In addition, thigh magnetic resonance imaging will be used to obtain measures of skeletal muscle and fat distribution; also, the muscle diameter will be quantified. Pathology of cartilage surfaces, meniscus, ligaments, and bone marrow will be analyzed using a modified Whole-Organ Magnetic Resonance Imaging Score (WORMS). Cartilage T2 maps, volume and average thickness will be calculated at the patella. The KL-Score will be assessed at the plain radiographs.