Normal Maturation of the Distal Femoral Epiphyseal Cartilage: Age-related Changes at MR Imaging

Purpose: To determine how signal intensity in the cartilaginous distal part of the femoral epiphysis varies with (a) age, (b) sex, and (c) distribution to the medial or lateral condyle on magnetic resonance (MR) images.

Materials And Methods: Sixty-six sagittal T2-weighted or inversion-recovery MR images of the distal femoral epiphysis in children aged 2 months to 5 years 5 months were evaluated. Epiphyses were categorized into five types on the basis of progressive signal intensity changes within the epiphyseal cartilage along the weight-bearing region and posterior condyles. Epiphyseal type was compared with age, sex, and distribution of signal intensity changes within the condyle.

Results: In early infancy, epiphyseal cartilage was homogeneous. During the 2nd year, signal intensity along the weight-bearing region decreased. With further advancing age, signal intensity in the posterior femoral condyles increased and became progressively more focal. The increase in epiphyseal grade correlated with age for both the medial and the lateral femoral condyles (r = 0.71 and r = 0.77, respectively; P < .001). There was no significant difference in epiphyseal changes between boys and girls or between medial and lateral condyles.

Conclusion: There is normal age-related variation in MR imaging signal intensity within the cartilaginous epiphysis of the distal femur. This may be related to weight bearing and epiphyseal maturation and should not be confused with disease.