A New Ankle Ligament Complex We Never Knew About

POSTED ON 11/3/2018 IN Foot and Ankle BY Chris Centeno

third ankle ligament complex

It's crazy that at the beginning of the 21st century we're still discovering ligaments that we didn't know existed. A few years back it was an important knee ligament, and now it's an ankle ligament. How is this possible? We were all poisoned by Netter. Let me explain.

Anatomy Class and Surgery Are All Artificial Representations of Actual Anatomy

Way back when in anatomy class as we dissected our cadavers to learn where everything lives in the body, we kind of knew that we were bulls in the china shop of the actual anatomy. Trying as hard as we could to define the structures they wanted us to see, we inadvertently destroyed others. I've seen the same behavior in arthroscopic surgery. For example, critical stem cell reservoirs of the knee are the fat pads that live just under the kneecap and around the middle ligaments (ACL/PCL). However, these fat pads are in the way of visualizing other structures, so they are often cut out by the surgeon. Does this make common sense to sacrifice stem cell reservoirs to improve the view? Nope. But you quickly see why we're still discovering ligaments in the early 21st century, as surgeons are also bulls in the china shop of the actual anatomy.  

Poisoned by Netter

One of the most brilliant anatomical illustrators of the 20th century was Frank Netter. Hit any Wikipedia page on anatomy and his images will be prominently featured, even decades after this death in the early 1990s. He was a surgeon, so he provided us the "cleaned up" view of the body that surgeons prefer. This is called "overdissection," which is when you try to make the anatomy look logical to human eyes by destroying key structures. 

When you first start to master ultrasound imaging, you quickly learn just how bad Netter's drawings were versus the real McCoy. Nothing viewed through an ultrasound image of the live body looks remotely like his drawings or any other anatomical drawing you've seen. In fact, even MRI pales in comparison because in ultrasound images you can see the body move and react. What's different? Everything has a crazy level of connectedness that you were not taught existed.

What do I mean? Muscle tendons that are supposed to end at a certain spot really don't, they just blend into another tendon. Ligaments that are supposed to look like distinct structures (as you recall from Netter's drawings) are closely adherent and aren't distinct. In fact, pretty much everything is a ligamentous complex. Meaning a group of thickened bands of tissue that we were taught had unique names and functions are really a whole complex working together to accomplish a biomechanical task. It's that connectivity that Netter and medical school eliminated that underlies the reason that we're still discovering ligaments.

What We Already Know About Ankle Anatomy

While our focus today is on ankle ligaments, it’s important to understand that the ankle joint is also made up of other structures, such as bones, nerves, and tendons. The proper functioning of the ankle is a precise collaboration among all of its structures. The ankle joint actually consists of a series of small joints, but the tibiotalar joint is the main ankle joint. It connects the lower ends of the leg bones (the tibia and fibula) with the talus bone. The talus bone rests between the lower-leg bones and the heel.

What we already know about the ankle ligaments is that there are many ligaments on the inside and outside. These ligaments provide support for and enable very precise movement of the ankle. Individual ligaments that support the medial, or inside, of the ankle are called the deltoid ligaments and there are anterior, middle, and posterior parts. Individual ligaments that support the lateral, or outside, of the ankle include the posterior talofibular (PTF), anterior talofibular (ATF), and calcaneofibular (CF) ligaments.

New Ankle Ligament Complex Discovered

The new study reported findings on examinations of 30 human ankle specimens that had no prior foot or ankle injuries, surgeries, joint stiffness, or instabilities. The first thing that the authors describe is "overdissection." By that, they mean the penchant for anatomists and surgeons to destroy important structures by trying to make their view look like the anatomy pictures they remember. Sound familiar? 

ankle LFTCL complex

Researchers found that when you don't overdissect, the front part of the anterior talofibular ligament (ATF) is actually a distinct structure. The back part of the ATF shares a connection with the CF ligament with both structures connecting at the same spot on the fibula (lower leg bone). It’s these two ligaments that form one functioning unit, now known as the lateral fibulotalocalcaneal ligament complex (LFTCL, in blue above).

So why is it important that we’ve found a new ligament complex in the ankle that we didn’t know existed before? Because this means that we've messed up countless ankle ligament reconstruction surgeries due to overdissection and not recognizing this new ligament complex. Interestingly, the authors noted that when both the ATF and CF ligaments are ruptured, repairing just the ATF seemed to work well. 

Ankle Pain and Instability Shouldn’t Go Untreated

Our ankles are prone to sprains. They are expected to support our entire body weight as well as navigate every obstacle in our walking path day in and day out. All it takes is one wrong step, and a twisted ankle can create ankle pain and long-term instability if left unaddressed. In addition, that untreated ankle instability can create excessive wear and tear on the joint and result in arthritis over time.

If the ankle sprain is severe or accompanied by a ligament tear, your doctor might recommend surgery, but ankle surgery often results in arthritis over time and other big risks, such as abnormal motion, chronic pain, lengthy rehabilitation, and so on. In addition, the study above also suggests that surgery may be destroying the ligament fibers that are now known to be important structures in the newly discovered LFTCL complex. Additionally, since there are interventional orthopedic solutions for ankle instability, in most cases, surgery can be avoided.  

For that last treatment, precise injections of your own healing platelets or stem cells are used to prompt repair in damaged ligaments. This is much less of a bull in the china shop than surgery and preserves the natural connections, which I've shown this morning are pretty complex. So please avoid ankle surgery if you can!

The upshot? It's cray cray that in the early 21st century we're discovering ligaments and other anatomical structures we didn't know existed! This is a problem when your only approach is to chop out damaged ligaments and try to replace them, as if you don't know the correct anatomical connections of these ligaments, what you install will, at best, be a very bad copy of the original equipment. Hence, a much better approach is to get the damaged ligaments to heal through precise interventional orthopedics!


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