Physical activity is associated with changes in knee cartilage microstructure

• Published in: Osteoarthritis and cartilage 2018-06, Vol.26 (6), p.770-774
• Main Authors: Halilaj, E., Hastie, T.J., Gold, G.E., Delp, S.L.
• Format: Article
• Language: English
• Subjects: Accelerometry; Cartilage microstructure; Cartilage, Articular - anatomy & histology; Cartilage, Articular - diagnostic imaging; Exercise; Humans; Knee Joint - anatomy & histology; Knee Joint - diagnostic imaging; Magnetic Resonance Imaging; Male; Middle Aged; MRI; Multivariate statistical modeling; Physical activity
• ISSN: 1063-4584; 1522-9653
• DOI: 10.1016/j.joca.2018.03.009

The purpose of this study was to determine if there is an association between objectively measured physical activity and longitudinal changes in knee cartilage microstructure. We used accelerometry and T2-weighted magnetic resonance imaging (MRI) data from the Osteoarthritis Initiative, restricting the analysis to men aged 45–60 years, with a body mass index (BMI) of 25–27 kg/m2 and no radiographic evidence of knee osteoarthritis. After computing 4-year changes in mean T2 relaxation time for six femoral cartilage regions and mean daily times spent in the sedentary, light, moderate, and vigorous activity ranges, we performed canonical correlation analysis (CCA) to find a linear combination of times spent in different activity intensity ranges (Activity Index) that was maximally correlated with a linear combination of regional changes in cartilage microstructure (Cartilage Microstructure Index). We used leave-one-out pre-validation to test the robustness of the model on new data. Nineteen subjects satisfied the inclusion criteria. CCA identified an Activity Index and a Cartilage Microstructure Index that were significantly correlated (r = .82, P