Ye Q, et al. - Using the intraclass correlation coefficients, Bland–Altman plot, standard error of measurement, and minimal detectable change, researchers determined the intra-observer, inter-observer, and inter-scan reliability of common patellar instability (PI) measurements on magnetic resonance imaging (MRI). Patients were eligible to be included in the research if they had at least two identical knee MRI exams performed on the same MRI unit within six months. The authors concluded that all PI measurements demonstrated satisfactory intra- and inter-observer reliability on MRI. Except for the angle of Grelsamer, congruence angle, and patellar trochlear index, most measurements showed adequate inter-scan reliability.