"normal: 0.37 (range 0.09–0.65) 1"
"It has been found to be a reliable measure of patella height, although has a better intra- and inter-observer reliability on MRI than x-ray 3."
"A: length from the anterior physeal line of the femur to the superior margin of the patellar articular surface"
"B: length of the patellar articular surface"