Growth plate of the normal knee: Evaluation with MR imaging

The purpose of this study was to establish the characteristics at magnetic resonance (MR) imaging of the normal physis of the tibia and of the fibula during development and maturation. Sixty MR imaging studies of the knee were performed in male and female subjects aged 1-20 years who had no clinical symptoms or radiographic abnormality in the lower extremity. Images obtained with both T1-weighted and field-echo pulse sequences were reviewed to establish developmental characteristics of the distal femoral and proximal tibial growth plates. Four stages of physeal development were identified. A fieldecho pulse sequence with repetition time of 700 msec, echo time of 20 msec, and a flip angle of 40° best depicted growth-plate cartilage. Some coronal and sagittal images of the normal knee show discontinuity of the physeal cartilage (drop-out sign), which should not be mistaken for premature closure.