Patients younger than 13-15 years old often still have some degree of growth continuing at the knee. ACL reconstruction surgery involves drilling tunnels into the thigh bone and leg bone. This may result in injury to the growing zones of the knee. This might cause a stoppage of the growth on that knee, or may cause the knee to grow abnormally (one side of growth plate damaged and not growing, which the other side of the growth plate continues to grow).
Traditionally many surgeons in the past would have advised these younger patients who have torn their ACL to "stop sports until you're 16 years old and then get your ACL reconstruction done". Unfortunately there is a lot of recent research evidence from top childrens hospitals around the world, that this is not the right approach. It is impossible to "stop kids from playing". Even if they are taken off the soccer, netball or rugby team, they are often still in school or downstairs with their friends playing, jumping and kicking as normal kids do. Studies have shown that a delay in performing ACL reconstruction in younger teenagers "to wait for growth" results instead in the development of severe cartilage and meniscus tears because the knee continues to be unstable. Many of these unnecessary cartilage and meniscus injuries might not be reparable, could have been avoided with ACL reconstruction surgery, and may have a negative impact on the long-term future durability of the knee.
As such, the best recommendation is to have the ACL reconstruction performed, but in a modified way so as to avoid damaging the growth plate. 2 main techniques have been recommended. One technique avoids drilling tunnels altogether, another technique is to drill tunnels, but in different directions from an adult ACL reconstruction so as not to damage the growth plate.
The exact ACL reconstruction technique required should be discussed with your surgeon. In fact the amount of growth remaining in most girls aged 13 years and older, and most boys aged 14-15 years and older is so little, that often a standard ACL reconstruction can safely be performed without the need for special techniques.