Wirth W, et al. - A total of 120 radiographically normal knees from the Osteoarthritis Initiative were examined by the researchers in order to develop a model of early osteoarthritis, by investigating whether radiographically normal knees with contralateral joint space narrowing (JSN), but without contralateral trauma history, illustrated higher longitudinal cartilage composition change (transverse relaxation time; T2) in comparison to the subjects with bilaterally normal knees. Of 60 Kellgren Lawrence grade [KLG] 0 case knees, 21/22/13/4 demonstrated contralateral JSN 0/1/2/3, respectively. In comparison to matched KLG0 reference knees, the longitudinal raise in the deep layer cartilage T2 between Y1 and Y4 was observed markedly higher in the 39 KLG0 case knees with contralateral JSN. In superficial T2 change, no important variations were recognized. T2 at Y1 was markedly higher in the case in comparison to the reference knees, especially in the superficial layer of the medial compartment. Hence, in contrast to bilaterally normal knees, radiographically normal knees with contralateral, non-traumatic JSN, demonstrated an appropriate model of early osteoarthritis, with deep layer cartilage composition (T2) changing more rapidly.