Qualitative and quantitative measures of prefemoral and quadriceps fat pads are associated with incident radiographic osteoarthritis: data from the Osteoarthritis Initiative

Summary Objective To determine if qualitative and quantitative measures of prefemoral fat pad (PFP) and quadriceps fat pad (QFP) are associated with incident radiographic osteoarthritis (iROA) over 4 years in the Osteoarthritis Initiative (OAI) study. Design Participants in this nested case-control study were selected from the OAI study with knees that had a Kellgren Lawrence grading (KLG) = 0 or 1 at baseline. Case knees were defined by iROA (KLG≥ 2) over 4 years. Control knees without iROA were matched 1:1 with case knees. Magnetic resonance images (MRIs) were read at P0 (time of onset of iROA), P-1 (1 year prior to P0) and baseline, and used to assess PFP (i.e. prefemoral hyperintensity alteration, patellofemoral hyperintensity alteration, maximum axial area) and QFP (i.e. hyperintensity alteration, mass effect, maximum axial area). Conditional logistic regression analyses were performed to assess the associations between PFP/QFP measures and iROA, after adjustment for covariates. Results 354 case knees with iROA were matched to 354 control knees. 66.9% of the participants were female, with an average age of 60.1 years. PFP prefemoral hyperintensity alteration measured at three time points (OR [95%CI]: 1.46 [1.18–1.82], 1.50 [1.20–1.88], 1.52 [1.22–1.89] respectively), PFP maximum axial area (OR [95%CI]: 1.07 [1.01–1.14], 1.08 [1.01–1.15], 1.08 [1.02–1.15] respectively) and QFP hyperintensity alteration (OR [95%CI]: 1.59 [1.27–2.00], 1.44 [1.13–1.82], 1.38 [1.09–1.73] respectively) were significantly associated with iROA in multivariable conditional logistic analyses. QFP mass effect measured at BL and P-1 (OR [95%CI]: 1.42 [1.11–1.82], 1.33 [1.01–1.73] respectively) were significantly associated with iROA. Conclusions Qualitative and quantitative measures of PFP and QFP are associated with increased iROA over 4 years.