Association of hyperintense signal alteration in the prefemoral fat pad and the worsening of patellofemoral osteoarthritis-related structural damage

To describe the cross-sectional and longitudinal associations between MRI hyperintense signal alteration of prefemoral fat pad (PFP) and patellofemoral structural damage in older adults. We used data from the incident osteoarthritis (OA) cohort of the Pivotal Osteoarthritis Initiative Magnetic Resonance Imaging Analyses (POMA) study. A convenience sample included 708 subjects at baseline and left 540 subjects at 24-month follow-up. Sagittal intermediate-weighted (IW) fat-saturated 2D turbo spin-echo (TSE) sequence was used to assess the presence of PFP hyperintense signal alteration at baseline. Baseline and 24-month semi-quantitative MRI Osteoarthritis Knee Score (MOAKS) variables for cartilage damage and bone marrow lesions (BMLs) were involved in this study. Regression analyses were applied to investigate the associations between baseline PFP hyperintense signal alteration and concurrent baseline MOAKS variables and their worsening in follow-up, adjusted for variables associated with patellofemoral and tibiofemoral OA. Baseline PFP hyperintense signal alteration was significantly associated with concurrent patellofemoral cartilage damage and BMLs cross-sectionally, as well as subsequent structural worsening of patellofemoral cartilage damage and BMLs longitudinally. Overall associations showed consistently significant associations in the lateral patellofemoral joint [adjusted OR (95% CI): 2.48 (1.63–3.76) cross-sectionally; 2.48 (1.47–4.18) longitudinally]. PFP hyperintense signal alteration was associated with lateral patellofemoral osteoarthritis-related structural damage cross-sectionally and longitudinally in older adults, suggesting that it may serve as an important imaging marker in patellofemoral osteoarthritis. The study was registered in ClinicalTrials.gov on March 24, 2004, with registration number NCT00080171.