Our daughter, age 11, first got her bone age done when she was two. From that point it has been a bi-annual exam with the endro and wrist x-ray. This was to confirm the bone age and that she was not growing to fast thus stunting her growth during puburiety. The reading is subjective, however it one more piece of data to weigh with the androstien, 17OH, renin, and growth chart. We are all idiviguals with different growth patterns. A child may be in the 50th percentile but have a bone age 2 years over the chroniclogical age. Or vise-vera. Point -more data more opinions--sort it out --and you be the final judge-- to many doctors make errors just like accountants, teachers ,etc.