Better Fix for Kids' Torn Knee

Older adults may not need surgery to fix a torn anterior cruciate ligament (ACL - the ligament that keeps the shin bone in place). But young children who have a lifetime of sports activities ahead of them will.

New research reports on the most recent techniques to repair this injury.

All-Inside, All-Epiphyseal ACL Reconstruction (AE) may be a better way to repair the ACLs of children, compared to another common type of ACL reconstruction for children.

Ask your doctor which ACL surgery is best.

It can be hard to perform ACL reconstruction on people who are still growing. If ACL reconstruction in children was done the same as in adults, the replacement ligament would be drilled through the patient's growth plate (the area of growing tissue at the end of long bones), which could make a patient's legs grow unevenly or with deformities.

For their study, Frank Cordasco, MD, of the Hospital for Special Surgery in New York, and colleagues set out to compare these two ACL reconstruction methods for children: the AE method and the over-the-top reconstruction. Both methods try to reduce contact with the growth plate.

The researchers found that both methods worked similarly well.

However, ACLs reconstructed with the AE method worked better when the knee was bent 15 degrees - a common position when someone is running.

"The AE technique is not available except in a few select centers around the country including the Hospital for Special Surgery," said Dr. Cordasco.

"We believe the AE should be the preferred procedure for ACL reconstruction in the skeletally immature [i.e., growing children]," he said.

In their study, the researchers used legs from deceased humans with unbroken ACLs. Using a robot, they tested different positions, motions and levels of stress on the knee.

Then they tore the ACLs and ran the same tests. Afterwards, they reconstructed 10 ACLs using each of the reconstruction methods.

To make the replacement ligaments the same size for each method, the researchers used a thicker replacement ligament to test the over-the-top technique. As such, over-the-top surgeries may have worse results in actual patients who have the smaller replacement ligament.

Just a couple decades ago, doctors rarely saw children and teens for ACL injuries.

But today, ACL injuries are much more common, as children are starting sports at younger ages and play at more intense levels. Many of these young athletes are focused on just one sport, which may put them at risk of injury from overusing their joints and muscles.

With this kind of injury becoming more common in children, it is important to know which surgeries lead to the best results.

Past studies compared joint stability after reconstruction with these two methods. This study by Dr. Cordasco and colleagues is the first to compare contact stresses on the knee.

According to Dr. Cordasco, both reconstructions improved joint stability and contact stresses but neither method fully restored the knee to its normal state.

Knees reconstructed with the over-the-top method could handle more stress at a 15 degree bend, compared to those repaired with the AE method, he said.

"This is important because most field and court sports involve knee function close to this position," he said.

Dr. Cordasco pointed out that over-the-top reconstruction requires an opening in the skin, which increases the risk of complications.

"We believe the AE is preferable in the pediatric and young adolescent population," he said.

This study was presented July 13 at the American Orthopedic Society for Sport Medicine's annual meeting in Baltimore. As such, the research has yet to be published in a peer-reviewed academic journal.