Juvenile osteochondritis dissecans (JOCD) is a disease affecting the knee joint of young active patients that can lead to early osteoarthritic changes. JOCD lesions are formed deep to the articular cartilage with late changes in the overlying articular cartilage. Our study was motivated by clinical observations that the opposing articular cartilage might be affected early. In this study, we observed a significant increase in T2* relaxation times in the articular cartilage of the medial tibia directly opposing the lesions when compared to the control region on the lateral site. These findings might indicate compositional changes in the tibial cartilage matrix due to increased biomechanical loading. Further study of T2* mapping as a potentially clinically realizable method to stage and prognosticate JOCD are warranted.