How strong are teenage vertebra?

I can imagine that this post will make me unpopular with some but I feel that this subject needs some attention. There is no fixed age that in the teens or even people in their early 20’s can be sure they have stopped growing. The growing vertebral body is not as strong as the fully developed. Growing spines have more cartilage growth centers on the top and the bottom and are prone to fracture. If care is not taken to limit the compressive loading on the spine ( think squats and deadlifts) a condition known as Scheuermann's disease may develop. Scheuermann's disease involves fractures of the top and bottom of the vertebral bodies. Scheuermann's disease can be painful and the spinal deformities are often permanent. 

The prevailing method of measuring spinal maturity has been to take x rays of the long bones  an look for the growth plates. As you can see in the x-ray of the knee below the  growth plates are line of cartilage where the growing body adds new bone tissue. 

The idea being that once the growth plates have closed the person has likely stopped growing and has reached skeletal maturity. Unfortunately, there is no sure way to X-ray the spine to see if the growth plates are closed. The vertebral bodies do not have growth plates like the long bones ( arms and legs.) Rather the spine has growth centers that are located on the top and the bottom of each vertebra. The spinal growth centers can not be seen on x ray, are made of cartilage and do not stand up to compressive force like bone.  Once the growth plates of the long bones have closed the spine can continue to grow for up to two years.