Zhao C, Gao X, Liu Q, et al. - A within-person knee-matched case-control study was performed to evaluate the relation of trochlea morphology and patellofemoral alignment to prevalent radiographic patellofemoral osteoarthritis (PFOA). Researchers selected individuals with unilateral radiographic PFOA from the Multicenter Population-based Osteoarthritis Study (MPOA) in three towns in northern China that was approved by Peking University Health Science Center Ethics Committee. They applied posterio-anterior and skyline views of the knee to measure radiographic PFOA, radiographic tibiofemoral OA, sulcus angle, patellofemoral index and patella displacement.  Sulcus angle, patellofemoral index and patella displacement were divided into quarters and investigated the relation of each of these measures to prevalent radiographic PFOA. This study included a total of 451 individuals (mean age: 65.2 years, women: 66.8%). Evidence suggested that extreme sulcus angles as well as higher values of patellofemoral index and patella displacement were correlated with higher prevalent radiographic PFOA.