New measurement of patellar height in the knees of children using the epiphyseal line midpoint.

The height of the patella was reevaluated by the ratio of the distance from the center of the patella to the epiphyseal line midpoint in the proximal tibia (PT) to that between the distances of the distal femur and of the proximal tibia (FT) on 59 knees of 36 normal children whose ages ranged from 3 to 18 years (average 10.6 years). The averaged ratio of PT to FT was 1.31 +/- 0.9 at full extension and gradually decreased to 0.99 +/- 0.06 at 90 degrees flexion. Changes in value were minimal within the range of 0.99-1.20 in the range of knee flexion from 30 to 90 degrees.