NORMAL MATURING DISTAL TIBIA AND FIBULA - CHANGES WITH AGE AT MR-IMAGING

PURPOSE: To describe the normal appearance of the maturing distal tibia and fibula at magnetic resonance (MR) imaging. MATERIALS AND METHODS: The authors retrospectively studied 50 MR examinations of patients aged 2 months to 21 years, dividing them into six developmental groups according to the appearance of the distal tibia and fibula. Epiphyseal ossification, physeal closure, and the signal characteristics of physeal cartilage were evaluated. RESULTS: Distal tibial epiphyseal ossification and physeal closure both began anteromedially and usually occurred earlier than in the fibula. The tibial physis developed an anteromedial undulation (Kump hump) before closure; volume averaging at the Kump hump simulated premature closure. The cartilaginous epiphysis had a lower signal intensity than the physis on T2-weighted images. The physis was most conspicuous on gradient-recalled-echo and fat-suppressed spin-echo proton-density-weighted images. CONCLUSION: Developmental cartilaginous and bone changes in the distal tibia and fibula follow a definite pattern and are well seen at MR imaging.