Normal epiphyseal cartilage measurements in the knee in children

Objectives-Thepurpose of this study was to validate previously reported distal femoral cartilage measurements in healthy children of different ages using an alternative sonographic imaging plane and patient position than previously reported and to provide preliminary proximal tibial epiphyseal cartilage measurements in healthy children. Methods-Distal femoral and proximal tibial epiphyseal cartilage thickness was measured using sonography in a cohort of healthy children based on a coronal image at the medial aspect of the femorotibial joint with the knee in 30° of flexion. The average of 3 measurements of femoral and tibial epiphyseal cartilage was obtained and correlated with age and sex. Femoral epiphyseal cartilage measurements were compared to recently reported measurements at the patellofemoral joint. Results-Sixty children (31 boys and 29 girls; newborn to 21 years; mean, 9 years; median, 7 years 11 months) were imaged. Seventy-four percent of distal femoral cartilage epiphyseal measurements fell into the 95% confidence intervals predicted by previously published reports. At age ranges outside those previously reported, there was less concordance between measured cartilage thickness values and those predicted. Conclusions-Valuesof distal femoral epiphyseal cartilage thickness measured by sonography of the femorotibial joint are similar to those reported at the patellofemoral joint. We propose that femoral epiphyseal cartilage thickness be measured on the basis of a coronal image at the medial femorotibial joint. This technique requires less knee flexion, which may prove advantageous when evaluating cartilage in patients with joint inflammation and a limited range of motion. It also allows concurrent measurement of tibial epiphyseal cartilage and thus provides another parameter for assessing cartilage loss.