The first time I tore my ACL — or anterior cruciate ligament, if you want to be precise — I collided with a hulking defender in a co-ed soccer league. I had no idea what that popping sound in my knee was; it just hurt like hell. But my teammates, all medical interns, did. From their faces, I immediately understood the noise wasn’t good.
Some 20 years and two reconstruction surgeries later, my left ACL is torn for the third time. Thanks to this unfortunate hat trick, I now know more than I ever imagined possible about this centimeters-long piece of collagen. One in approximately 3,500 people will hurt their ACL at some point in their lives — in fact, the ACL is involved in almost half of all knee injuries. Playing sports like soccer, basketball, football, and skiing heightens the risk of a tear, because such activities skew heavy on the kind of cutting lateral movements and quick changes of direction that typically cause an ACL to tear during running or jumping. Anatomy also plays a role: Women are three to six times more likely to suffer ACL injuries than men are, according to a study published in the peer-reviewed British Journal of Sports Medicine.
“Our pelvises are a little wider, so it puts more stress on the knee because the angle from the hip to the knee is wider in women than men,” explains Pamela Mehta, M.D., a board-certified orthopedic surgeon and founder of Resilience Orthopedics in San Jose, California. “Men can take a greater torque to their knee before they tear their ACL, and for women, it doesn’t have to be that pronounced. It can just be like a simple twist the wrong way or landing the wrong way.” Here’s what to know about the little ligament that can spell big trouble, and what to expect if you happen to find yourself in what’s sometimes known as the ACL Club.
What is an ACL?
A major stabilizing ligament that runs diagonally through the middle of the knee and connects the femur to the tibia. According to the Cleveland Clinic, there are three grades of ACL injury: grade one, in which the ligament has overstretched but remains intact; grade two, in which it tears partially but remains connected to the bone; and grade three, in which it tears in two.
How common is a torn ACL?
Again, very. According to National Institutes of Health statistics, more than 400,000 ACL surgeries take place every year. Some anecdotal evidence to round out the data: About a half-dozen of the top players eligible to compete in the 2023 Women’s World Cup — including Catarina Macario, an up-and-coming standout for the U.S. Women’s National Team — were sidelined from the tournament with ACL injuries.
How do you know if you’ve torn your ACL?
It’s not always easy to know for sure whether that post-game pain in your knee is from a torn ACL or a simple sprain. But there are a few key warning signs to be aware of. One is pronounced knee swelling after a sudden twisting movement or change of direction. You may also hear that dreaded popping, which is the sound the actual ligament makes when it tears, explains Shawn Anthony, M.D., associate chief of sports-medicine service at Mount Sinai Health System. But the number-one symptom he sees in patients is instability, Anthony explains, the feeling “that they can’t trust that knee anymore, and it often gives way.”
As a first step toward a diagnosis, your doctor will likely perform what’s known as the Lachman test: bending the knee about 20 to 30 degrees and pulling the shin forward. An MRI is another common way to detect a tear, and CT scans also can be used.
How do you fix a torn ACL?
Most ACL injuries require surgery, especially when they happen to high-level athletes hoping to return to competition.
The bad news if you’re facing one? It’s a major surgery, especially if it’s an ACL reconstruction. Unlike an ACL repair, in which a surgeon can use a graft to stitch together the two ends of an ACL that are still attached to bone, a reconstruction involves several additional steps. First, the surgeon must drill holes, or tunnels, into the bone for the new ligament to attach to. The damaged ACL is replaced with tissue that’s either harvested from a patient’s own body — sometimes from the patellar tendon, sometimes from the hamstring — or from donor tissue, known in medical terms as an allograft.
The good news is that the field has seen some significant advancements lately. One is the improvement of knee arthroscopy technology, which utilizes a miniscule camera to look inside the knee, assess the injury, and treat it. Such scopes also allow for more accurate ACL reconstructions, enabling doctors to more exactly pinpoint the place they’ll drill tunnels into the bone. “Tunnel location is the number one prediction of good outcomes,” Anthony says.
In addition, Anthony notes many of the patients who would have undergone a full reconstruction may be candidates for a repair, which is a more minimally invasive procedure with comparable outcomes to traditional reconstruction. He points to a procedure known as BEAR (or, bridge-enhanced ACL restoration) that has resulted in what he calls “a huge paradigm shift” over the last few years. The procedure uses a collagen-based implant to “bridge” the torn ACL; as an example of its efficacy, Anthony points to patients who have received a standard reconstruction on one knee and a BEAR repair on the other.
“They universally have said that six months out to one year out, their BEAR ACL repaired knee feels more natural, more stable,” he says. “It feels different, it feels more normal compared to a reconstructed ACL.”
How long does it take to recover from an ACL injury?
Unsurprisingly, recovery is a mentally and physically grueling process. First, you’ll be hobbling around on crutches for a couple of weeks. Then, there’s the physical therapy: approximately two to three sessions a week for at least six months, often longer (and often depending on how much your insurance will cover). Many orthopedic surgeons tell their patients to anticipate a full year to be able to fully return to their pre-injury activity levels.
“People who tear their ACL are generally pretty active people, and they’re not used to being sedentary,” Mehta says. “They take for granted that they can just walk normally and run and bike and all those things. So I think being prepared that it is going to take one full year to get back to your pre-injury self is really important.”
Is surgery always necessary?
Not always. Mehta is a prime example: After tearing her ACL while skiing, she opted to not have the surgery, instead focusing on rehabbing the knee and doing exercises to strengthen the muscles around it.
“We have lots of ligaments and muscles in our body, and they can often do the job for the ones that are torn,” she says. “So you can strengthen your knee to a point that you don’t need to have the ACL surgery.”
In addition, people who do have an ACL-deficient knee — that’s doctor-speak for one with a torn ACL that hasn’t been surgically repaired — can benefit from custom braces specifically designed to support the knee, essentially functioning as the ACL. Mehta wears one while skiing, but also notes that it’s the only “cutting” sport she continues to do. However, if you’re a high-level athlete or you can’t live without playing soccer or basketball, then surgery is often the best choice.
Currently, I’ve opted to hold off on my third surgery, at least for now. I gave up soccer a long time ago, but I’m grateful that I can still do my longtime workout of choice, running, even though I’ve reduced my mileage. I’ve also added quad-strengthening squats into my routine, and I’ve dug out my knee brace — a purple, custom-fit contraption I got after that first injury — to help give me more stability when I’m kicking the soccer ball around with my son. Thankfully, Roboleg, as I nicknamed it, still fits.
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