Dr. Martin Leland on the Discovery of a New Knee Ligament

Proposed anatomy of the anterolateral ligament of the knee (Image via the Journal of Anatomy)

Anatomy of the anterolateral ligament of the knee (Image via the Journal of Anatomy)

Last month, surgeons from a hospital in Belgium announced that they had found a new knee ligament located on the outside, front part of the knee called the anterolateral ligament, or ALL. The Belgian surgeons, who published their findings in the Journal of Anatomy, say that this new ligament could explain why some reconstructive ACL surgeries have disappointing results because they don’t address potential injuries to the ALL.

J. Martin Leland III, MD

This seems like a surprising discovery after more than 100 years of knee dissections, surgeries and scans. And if it does contribute to overall joint stability, does that mean surgeons will have to rethink the way they reconstruct knees?

University of Chicago orthopedic surgeon Martin Leland, MD, was one step ahead of us, and posted a few thoughts on Twitter last night after some of his patients have already asked him about the new discovery.

Science Life spoke to Dr. Leland in more detail today about whether or not this really is a new ligament and how its discovery could affect those undergoing ACL surgery.

Science Life: What’s the significance of this discovery? Is it really a “new” ligament?

Martin Leland: It’s bringing attention to a ligament that’s kind of been described before, but no one really talks about. Robert LaPrade, who’s a sports medicine specialist at the Steadman Clinic in Vail, Colorado, has an article on his website about it, where he says congratulations to these researchers in Belgium for their “rediscovery” of this ligament. It was first described by a French surgeon named Paul Segond in the late 1800s. It’s always been there and it’s gone by numerous names. I wouldn’t take it away from them and say, no, this is clearly a well-known ligament, but it’s something that no one is really talking about currently.

Here’s the real problem though: I had a patient who I did an ACL reconstruction on, and they re-ruptured. I revised them about two months ago, and they wrote me an email last night saying, “Do you think this new ligament is why I re-ruptured? Maybe I tore that new ligament too.” A lot of people are starting to get very concerned, hence my tweets about it.

SL: Why do you think there’s so much confusion about it?

ML: There’s a lot of media coverage about it, and a lot of people are going to get very concerned because they didn’t have this ligament reconstructed in their knee. But what they don’t understand is, first of all, surgeons did know about this for quite some time, about aspects of this at least. But we don’t know its role at all. We have no idea if fixing it is going to make a difference, and there are so many other things that surgeons look for and pay attention to that are significant contributors to the stability of the knee. This is a very, very distant thing way down the road.

One of the things that some surgeons have compared it to—and I’ve also been talking about when it pertains to this—is there was a time about 30 years ago when they were adding what’s called an extra-articular aspect to ACL reconstruction. The ACL is inside the knee, so it’s intra-articular. At the time they were reconstructing the ACL, but then also putting a part called the iliotibial band, which is on the lateral side of the knee [where the new ligament is located], flipping it over and tacking it down. And quite frankly if you look at that surgery, you’d say, wow, even though they didn’t necessarily know the new ligament was right there, by doing this extra-articular reconstruction they were totally reconstructing this ligament that they didn’t know existed. And they found it gave no benefit whatsoever, and has been abandoned over the last 30 years. It gave no benefit by doing this extra piece. Now maybe they weren’t doing it perfectly anatomically or maybe there were some other issues, but in medicine, there’s a slogan: What’s old is new again.

SL: If it really is a separate ligament, what does it mean in the long run?

ML: In LaPrade’s article, at the very last line he says, “all of us look forward to seeing the results of those studies over the next 5 to 10 years.” That’s really the scope that we’re looking at. Patients are thinking that if they tear their ACL next week they’re going to get an anterolateral ligament reconstruction in addition to the ACL. This is something that’s going to take a decade to start figuring out, and if it’s ever appropriate, then it’ll be started. But it’ll be a decade before we’ll look at that.

SL: So it’s going to take years of looking at outcomes from reconstructions to see if repairing the ALL was really making a difference.

ML: Right. I would basically say this is the equivalent of the Wright brothers and putting a man on the moon. It’s like the Wright brothers started the process, but it took almost 70 years from the Wright brothers to put a man on the moon.

J. Martin Leland III, MD is a skilled orthopaedic surgeon and sports medicine physician. He provides expert care for adults and children with injuries of the bones, joints and muscles, and specializes in the care of sports-related injuries, with a particular focus on injuries of the shoulder and knee. You can follow him on Twitter @DrMartinLeland.

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Claes S., Vereecke E., Maes M., Victor J., Verdonk P. & Bellemans J. (2013). Anatomy of the anterolateral ligament of the knee, Journal of Anatomy, 223 (4) 321-328. DOI:

About Matt Wood (514 Articles)

Matt Wood is a senior science writer at the University of Chicago Medicine and nonfiction editor for Another Chicago Magazine.

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