Key Points:
- We are seeing more ACL injuries in young growing athletes than we used to several decades ago, and more young athletes choose to have early ACL surgery
- ACL surgery in a growing athlete requires special considerations to minimize chances of injury to the growth plates
- With proper techniques, risk to the growth plates is low and success rates for surgery are very good although results are not as good as they are for adults after ACL surgery
An ACL tear in growing athletically active kids is a challenging issue to manage from a 
surgeon?s standpoint. It appears that the number of young people sustaining ACL tears is on the rise, and in particular we are seeing more ACL injuries in kids who are not done with their growth.
As compared to kids who are still growing, teenagers who are done growing can be treated as adults when it comes to surgical decision making. Regardless of age, the main issue with a torn ACL is that the knee is typically unstable, making some sports and daily activities difficult. A knee with a torn ACL often gives way or buckles with activities.
Some surgeons will recommend that a young patient modify activity and possibly wear a brace until growth is finished, and then go through the ACL surgery. This is theoretically possible but it?s often very difficult to successfully manage a young person?s activity level, leading to quite a bit of unhappiness. This study showed that only 6% to 52% of young athletes were able to remain physically active to their desired level when managed without surgery, whereas 80% to 100% of young athletes managed surgically were able to successfully return to their desired level of activity. The surgical option tends to be much more appealing to most kids and parents.
The surgery for a torn ACL- called ?ACL reconstruction?- involves building a new ligament by drilling tunnels in the tibia and femur, and then placing a new tissue called a ?graft? in those tunnels. As the graft heals and matures it functions as the new ACL. In a young growing athlete the key consideration is that the areas of the bone where growth takes place, the ?growth plates?, can theoretically be damaged by the surgery. This means that there?s a chance that either the leg length or the angulation of the leg could be altered by the surgery.
Considerable research has gone into the ways to minimize risk to the growth plates during surgery. Some techniques involve modifications to the tunnel positions to avoid crossing the growth plates. Other research has studied the effects of various types of ACL grafts on growth using conventional surgery techniques.
Not surprisingly, in this relatively new area of ACL research there is some controversy. The growth plate sparing techniques may have somewhat reduced stability compared to a conventional technique. And some graft choices may have a higher risk of damage to the growth plate. For example, a patellar tendon graft with bone plugs is commonly used in adults but there appears to be a higher risk of growth disturbance if the bone plug crosses the growth plate. Hamstring tendon grafts and conventional tunnel drilling technique seem to have the best combination of stability, excellent return to sport, and low risk of injury to the growth plates.
Some recently published studies have shown excellent functional results from the surgery with low rates of bone growth issues. This study of surgery on young people with open growth plates using conventional surgical technique and hamstring grafts showed about 15% of kids with some x-ray evidence of growth issues at 4 years, but none of the issues was limiting to the young athlete. Interestingly, this study showed that during the 4 year follow up period 16% of the kids retore the ACL, and 16% tore the ACL in the other knee. Success rates are quite a bit higher in adults.
This is a controversial area with a number of important considerations when deciding treatment pathways. My advice if you?re a parent of a young growing athlete with an ACL tear is to seek the opinion of highly experienced sports medicine surgeons, or possibly a pediatric sports medicine specialist to assist you in your decision.
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