Additional Study Information: Growth of the skeleton happens at the growth plate, a disc of cartilage at the ends of all long bones. The purpose of this research study is to find out if a technique using investigational MRI called diffusion tensor imaging of the growth plate cartilage of the knee (MRI-DTI), is able to predict growth. For this purpose, we are studying children during the growth spurt, to see if MRI can predict how much they are going to grow in the next year and how tall they will be. We hope that this information will help people who have problems with growth of the entire skeleton or a limb. Participant will have MRIs at the beginning, at 4, 12, 24, and 36 months later. In each visit, participants will complete a short questionnaire. Participant will receive reimbursement for each visit.