3 Things Most People Don’t Know About ACL Surgery

If it seems like you are increasingly hearing about ACL (anterior cruciate ligament) injuries, it doesn’t mean you’re simply watching too much ESPN during the pandemic. 

You might also be hearing about it on the sidelines of your kids’ games. In those between age 6 and 18, this type of knee injury has steadily increased (2.3% annually) over the past 20 years, according to the American Academy of Pediatrics. And in children and adults who’ve had a torn ACL already, the odds of an ACL re-tear are as high as 20%.  

It’s the job of your ACL to keep your knee stable during quick changes in direction, a necessary function for sports like soccer, basketball, football, and lacrosse. An ACL injury, which can range from a sprain to a full rupture, is not only painful, but can put an abrupt end to an athletic season. 

These injuries often require surgery, as well as ample recovery time. In fact, many surgeons now recommend that patients wait nine to 12 months, sometimes even longer, before returning to their sport. There’s also an increased focus on preventing a re-tear of the ACL after surgery, says Elizabeth Gardner, MD, a Yale Medicine orthopaedic surgeon and head orthopaedic surgeon for Yale University Athletics. 

We talked with Dr. Gardner about this and other timely topics regarding ACL, and what stands out about Yale Medicine Orthopaedics. 

Most often, surgeons recommend ACL reconstruction after it tears. For this procedure, the surgeon will remove the damaged ligament and replace it with a new one, called a “graft,” which can be made of tissue from the patient’s own kneecap tendons or hamstrings—or from a deceased donor.  

One technique, which utilizes the quadriceps tendon, was developed by Yale Medicine’s John Fulkerson, MD. “Dr. Fulkerson is one of the pioneers of this technique, and although a small group of surgeons has been using it for decades, it is now being adopted nationally and internationally,” Dr. Gardner says. In the procedure, we use the tendon above—not below—the kneecap, she explains. 

“This graft has a lot of advantages for many of my patients. I have been incredibly lucky to learn from Dr. Fulkerson, who originally described his technique back in the ‘90s—you can’t find that type of experience everywhere.”  

Use of the quadriceps tendon can be especially beneficial to younger patients and those who play sports that require impact on the front of the knee, such as volleyball or wrestling, Dr. Gardner says. 

“While the quad and patella tendons have similar structures, the quad tendon is bigger and thicker. And it is located above the knee, rather than on the front of it,” she says. “As a result, when we take a graft from a quad tendon, we are not affecting the native tendon as much, and we are taking it from a less troublesome area of the knee.”  

This generally results in less pain with kneeling, jumping, and sports that cause impact on the front of the knee, Dr. Gardner adds. 

The ACL controls both the front-to-back and rotational movements of the knee. And while modern, minimally invasive surgical repairs of the ACL do a good job restoring control of these movements, the risk of re-tear remains higher than we would like, Dr. Gardner explains. In research studies, the risk of re-tear ranges from about 2% to 20%, depending on the patients studied.

One potential reason for the high re-tear rate is that there are some patients whose genetics or mechanics predispose them to re-injury, which commonly occurs with another rotational movement to the knee. “In terms of a re-tear, the surgeon may have done a very good surgery; it could simply be that those patients are very loose-jointed or they tend to move in a way that puts more rotational stress on their knee,” Dr. Gardner says.  

So, in addition to emphasizing rehabilitation after surgery (to improve the way a patient moves, thereby lessening stress on the ACL), surgeons are returning to a more traditional procedure that provides extra rotational support to the knee and further protects the ACL.

“Before we were able to treat ACL tears arthroscopically with a camera, it was common for surgeons to tighten a ligament on the outer side of the knee,” says Dr. Gardner. “This tightening procedure was typically done in lieu of replacing the ACL itself.”

Called the anterolateral ligament of the knee, its role in rotational stability has been discussed for many years. Recently, renewed attention has been focused on how it may play a role in modern surgery.

“As technology advanced, we abandoned this tightening procedure, and have spent decades perfecting our reconstruction of the ACL,” Dr. Gardner says. “However, surgeons have recently explored the possibility that certain patients may benefit from an anterolateral ligament procedure to provide added rotational stability to their knee.”  

Surgery on the anterolateral ligament can be either a tightening procedure or a reconstruction using another graft. It is typically performed at the same time as ACL reconstruction, usually via another incision, and it does not generally change the rehab timeline or how long it will take an athlete to return to their sport, she adds. 

“We don’t yet know exactly who might benefit most from this procedure—it is still being studied,” Dr. Gardner says. “But right now, I am considering it most for my patients who have re-torn their ACL graft or for those rare patients who are very rotationally unstable at the time of their initial ACL surgery.”

In addition to the concern about re-tears, recent studies have shown that more than half of people who tear their ACL develop knee arthritis five to 10 years after surgery. 

“This makes initial injury prevention very important,” Dr. Gardner says, adding that a special focus should be placed on testing athletes for strength deficiencies not only before an injury happens, but also both after their injury and before they return to their sport following surgery and recovery. “During rehab, we’re aiming to return the athlete to their prior level of strength and function; to do that, we focus on the neuromuscular process—to address the bad movement patterns that caused the initial ACL tear.” 

Furthermore, a greater emphasis on recovery time after surgery can help prevent the risk of re-tear from happening, Dr. Gardner says. 

“In the past, some doctors would clear an athlete to return to play six months after surgery, often without any good assessment of how the knee is doing on the field or court. But that is now the exception to the rule,” says Dr. Gardner. “Today, with an understanding that each patient is different, we often recommend at least a nine-month recovery time—sometimes more—for a return to pivoting sports.”