The distal femoral and proximal tibial growth plates: MR imaging, three-dimensional modeling and estimation of area and volume.

OBJECTIVE: To explore how the size of the growth plate changes with age using three-dimensional (3D) models of the distal femoral and proximal tibial growth plates in pediatric patients. DESIGN AND PATIENTS: We retrospectively created 3D models of the normal unaffected distal femoral (n=20) and proximal tibial (n=10) growth plates in 14 patients (9 males, 5 females) age range 3.8-15.6 years who were referred for evaluation of premature partial closure of the growth plate or hyaline cartilage abnormality. All patients had one or more 3D fat-suppressed spoiled GRASS sequence from which models were made of normal growth plates. Total projected area was estimated from standardized maximum intensity projection (MIP) views, and volume was computed from the entire model. We also included the total projected area of the distal femur (n=7) or proximal tibia (n=8) in 11 patients (8 males, 3 females, 5-13 years) who had previously been evaluated for bone bridging.
RESULTS: The 3D femoral and tibial growth plate anatomy was displayed. Femoral growth plate area varied from 804 mm2 to 3,463 mm2. Femoral physeal cartilage volume varied from 2.1 cm3 to 12.6 cm3. Tibial growth plate area varied from 736 mm2 to 3,026 mm2. Tibial physeal cartilage volume varied from 1.9 cm3 to 13.2 cm3. The growth plate area values appear to increase linearly with increasing age.
CONCLUSIONS: The distal femoral and proximal tibial physeal plates have complex anatomy. Both area and volume of the growth plates appeared to follow a linear increase with age and reached a plateau in adolescence, although there was some scatter. Area appears to have less measurement variability than volume, and may be a more reliable predictor of growth plate tissue quantity. Copyright 2004 ISS