All of those with a previous ACL injury please stand up. But, wait! Don’t do it too quickly. There is a good chance you will re-tear it again. Sarcastic humor aside, the risk of re-injury after an ACL tear is still rising, especially amongst high-school aged athletes over the past 20 years. And, to date, there are currently 7 professional NFL players who have gone down with an ACL injury before the 2020 season kicks off! Despite advancements in technology, testing, and surgical procedures, we are still no better at reducing the risk of ACL ruptures than we were in the 90’s. Where is the disconnect?

The disconnect is occurring where the rubber meets the road, at the feet. In this comprehensive look at current practice in rehabilitation and strength and conditioning, we will discuss the “steps” needed to take in order to get ahead of this ACL injury epidemic.

See The Forest Through the Trees

The current climate of ACL injury prevention or risk mitigation is characterized by three main components: Reductionist Thinking, Isolation, and Muscle Focused.

Most methods of ACL rehabilitation include localized treatments that focus on the bum knee rather than targeting the cause of the injury. Sure, localized treatment after surgery is warranted. A little E-stim to the quads, some massage to help flush fluid, or even some terminal knee extension with a resistance band are great in the early stages to reduce swelling, downregulate the pain response, and jumpstart neuromuscular recruitment. But, the sooner we can move away from isolation and into integration of movement, the better. Reductionist thinking when it comes to movement has a futile hope that focusing on one area at a time, like quad or hamstring strength, will have an impact on the whole system. Yet, we still see athletes with a quad index “within normal limits” who still re-tear their ACL (Losciale, 2019). Looking at the foot and how it impacts knee and hip function are vital for enhancing kinetic chain communication prior to return to play. This is even more important in later phases of the athlete’s rehabilitation journey and physical preparedness programs.

90% Isn’t Good Enough 

I believe there are many well intentioned strength coaches and providers out there who have the best interest of their athletes in mind. In fact, it is now (mostly) common practice to look elsewhere in the body when designing programs. We spend time testing glute strength, analyzing running mechanics, squatting and deadlifting until the cows come home, and comparing side to side differences in single leg hop stability. Yet, is it possible we are still looking in the wrong places? What happens when we have to legs that appear to be “symetrical” in size, strength, and stability, but come to find out that the non-injured side just regressed to that of the “bad leg,” resulting in two weaker legs? You may have an injured knee that is within 90% strength as the opposite side, but what context does that percentage represent? 90% of the weaker side? Many are leaving out one very important variable – what is occurring at the foot and ankle. If you are testing, assessing, and progressing with shoes on, you are doing it wrong.

Strength training success is usually viewed as the weight and the numbers going up in a particular lift. That means our athlete is getting stronger, right? Maybe…but in what way? Have we looked at the foot to determine how it is communicating with the knee and hip? The foot plays a critical role by creating a spiraling pathway that allows for force attenuation and dispersion. We need to be able to visualize how the foot is interacting with the ground. Looking at movement with shoes on leaves a very large piece of the biomechanical puzzle off the table.  Without analyzing the foot, we haven’t corrected the compensation patterns that led them to an ACL injury in the first place. Even if an athlete hasn’t sustained an injury, have we considered where the foot might be contributing to a deficiency  in their movement literacy? What are they missing? Otherwise, we could just be strengthening dysfunction, supporting the case that ACL re-rupture and initial injury rates are still on the rise, with an increase of 147.8 percent over the last 10 years, and increasing 2-3 percent annually according to the American Orthopedic Society of Sports Medicine (2019).

The Feet are Rooted in Movement 

The human body craves movement in all 3 planes of motion, and true athleticism expresses all 3 of those dimensions at any given moment in sport. Our body is designed to move in a variety of ways in order to withstand gravity and other forces, like a charging linebacker, in our environment.

The best way to improve all areas of athleticism, including balance, posture, alignment, speed, power, and strength, and reduce risk of future injury, is to teach our athletes how to utilize each and every joint position in the range of motion necessary given the context of their sport. Where does this three-dimension wave of motion begin? You guessed it. The foot. Our feet direct all of the rotatory and spiraling pathways up the entire kinetic chain that lead to seamless movement, torque production, and force attenuation.

The foot ultimately plays a much larger role in knee function than the hips.

In dynamic movement, muscles both lengthen and shorten…turning on and off with each step. This means that eccentric and concentric muscle contractions come together as a pair. They aren’t separate. Using the two together, instead of isolation, helps the brain and nervous system relearn how they are supposed to work in movement and sport. The isometric portion of the muscle contraction sequence occurs when the muscle has eccentrically lengthened into its most elongated state prior to the initiation of the concentric muscle action of force production, OR when the brain decides that it needs to change direction. We call all three of these contractions working together as motor control. Their ability to fire and wire together is dictated by joint position.

Joints Are the Drivers 

Many of the perceived “muscle deficiencies” we see following ACL injury are actually more of a joint problem than a tissue problem. Sure, we know that only 20cc’s of fluid,or swelling, at the knee joint following injury or surgery can inhibit quadriceps firing. ⁣However, what happens when most of the swelling is down and you still can’t get the quad to fire? More E-Stim? ⁣More Dry Needling? ⁣More Terminal Knee Extensions? ⁣More Leg Lifts? ⁣A focused attack on the muscle itself using these strategies won’t get you very far. ⁣We need to look at the joint, and how it’s moving. ⁣And, No, I am not referring to the knee joint. ⁣Instead, we need to travel down to the foot…yes, the foot. The position and pattern of the foot will dictate quadriceps firing capacity, and ultimately knee extension capability. ⁣The same can be said for knee flexion capacity and hip mobility. The foot’s shape – pronating or supinating – dictates the motions occurring at the lower leg, the knee joint, and the hip and pelvis.

You can’t extend the knee with a pronated foot, just like you can’t flex the knee with a supinated foot. Sure, you can bend it, but that doesn’t account for the motion occurring in the transverse plane – the rotational, spinning motion of the tibia and femur necessary to actually flex the knee and attenuate forces.

When you ask someone with feet that are stuck in pronation (foot flat) to extend their knees, you’ll see the quads turn on, but the knee won’t extend. It will only extend the knee as far as the joint will allow. We can fix this by encouraging the calcaneus to invert better, creating supination to  pull the foot out of pronation, initiating  instant extension of the knee. Knee extension requires the foot to be able to pull out of it’s pronated shape, allowing the quad to do it’s real forceful extension. ⁣So, if we want our athletes be able to turn on their quad after an ACL injury, we better start teaching them how to supinate.⁣

Knee Over Toe

The current paradigm of ACL rehabilitation fixates on trying to perform every movement with the knee over the toe in order to prevent any of that nasty valgus movement that is the catalyst for every ACL tear. Over the years we have deemed this knee over the second toe position as THE safe position for the knee, creating a dichotomy between movements – labeling anything outside this position as bad or unsafe. The science for this is strong, yet this doesn’t reflect all movement, especially in sport. Sure, when squatting a heavy barbell, having your knee stacked over your ankle and 2nd toe is probably a good idea, creating a stable pillar to lift a ton of weight. But, that position rarely occurs in sport. Just look at any NFL running back changing direction or even Usain Bolt coming out of the blocks.

In an effort to make the knee safe, we are actually making it weaker in the long term. At the same time, we are eliminating the role of the human foot and ankle as dynamic movers, excluding any possibility of a relationship between the foot, ankle, knee, and hip.

A safe knee is one that can move in accordance with the foot and ankle. Think about the mechanism behind an ACL tear. The foot gets planted in one direction and the knee goes in the opposite direction. More specifically, we see a foot that is collapsed inward (pinky toe coming off the ground) with the toes turned out. The knee then travels inwards while bending (not flexing). In this scenario, there is no coordination of muscles firing in the right way to stabilize the knee, because thee joints (starting with the foot) are out of position.

By teaching the foot how to remain in contact with the ground (all 3 points of the tripod) while pronating (flattening to the earth) and allowing the knee to safely come inside the big toe, we can establish a foot that is better at absorbing load and transmitting that energy through a spiraling pathway up to the hip.

By only training a knee over the second toe, , we are making the knee strong in one position that it may never get to experience on the pitch, court, or field. Just take a look at any running back, soccer player, or sprinter coming out of the blocks and you will be able to visualize the many different positions and relationships between the foot, knee, and hip in a given game or event.

Master Your Movement: Explore 

We shouldn’t be consciously fearful about limiting range of motion at the knee and ankle, trying to protect against damage. Instead, we need to explore these other positions that are 99% more likely for an athlete to experience. Awareness of the relationship between the hip, knee, foot, and ankle always leads to an improvement in performance and return to the playing field.

Failure to account for the foot will lead to long term  failure in ACL rehabilitation. Biomechanical function of the foot is just one aspect of best practice. In part 2, we will dive deeper into the sensory system housed in the feet, and how circus trick training on unstable surfaces makes you better at circus tricks, not a more durable athlete.

References:

1. Fältström A, Kvist J, Gauffin H, Hägglund M. Female Soccer Players With Anterior Cruciate Ligament Reconstruction Have a Higher Risk of New Knee Injuries and Quit Soccer to a Higher Degree Than Knee-Healthy Controls. Am J Sports Med. 2019;47(1):31-40. doi:10.1177/0363546518808006
2. Losciale JM, Zdeb RM, Ledbetter L, Reiman MP, Sell TC. The Association Between Passing Return-to-Sport Criteria and Second Anterior Cruciate Ligament Injury Risk: A Systematic Review With Meta-analysis. J Orthop Sports Phys Ther. 2019;49(2):43-54. doi:10.2519/jospt.2019.8190

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