Knee pain is highly disruptive to your life. Patellar tendonitis, meniscus issues, ACL tears, patellar tracking issues, your basic “ache in your knee”…all of them tend to last far longer and be more frustrating to heal than issues that arise in other areas of the body.
When you lose knee function, you are likely to see your body make adjustments and compensations both above and below the knee. Conversely, you can also see knee issues arise because of poorly functioning joints above and below the knee. Today, we’ll focus our attention on the knee itself and how it is build to function.
In this post, you’ll learn four movements your knee must be able to do if it is to function well (two of which most people do not know about, and are astounded to find they cannot do yet).
Knee Pain? Start Here
Having joints function as they are built to function is imperative. When your joint doesn’t function as it’s built to, you’re going to get compensations and adaptations to the hard and soft tissues that make up, and support, the joint. This can sometimes lead to pain and injuries.
Far too often, I see individuals seriously considering all manner of intensive and invasive treatments for their knee, and yet they’ve never actually looked to see if their knee is functioning like a knee.
You can do all of the treatments in the world, but if your knee is not functioning the way it is built to, you’re skipping over an important step. If your knee has full function and you still are having issues – then it makes sense to consider intensive and invasive treatment options.
There are several things your knee is supposed to be able to do. This is true regardless of your age, size, gender, or history. The only caveats here are for those with surgical changes to their structure. If you have a surgical change to your knee, you may not have exactly the same capacity that I outline here, and instead, your goal may be to “get as much of what is considered ‘normal’ as possible knowing it may never be the same as someone who has not had a surgical change to their joint.” Or maybe it will be. Worth finding out, eh?
Your Knee Is Built To Function & Move Like This
In addition to full flexion (bending of the knee), and full extension (straightening of the knee), your knee needs to be able to do two other crucial things…
And these two movements are frequently overlooked, yet are vital for the knee to adequately handle moving through life, activities, workouts, and sports.
I’ll cover those two movements first, then wrap up with details about knee flexion and extension that are important to know…
*Note: friendly reminder, you should not push into any movements that are painful. If you experience pain, you need to talk to a clinician to evaluate the pain and clear you for activity.
The three leg bones that meet at your knee joint are the femur (your thigh bone), your tibia (the larger “shin bone” of your lower leg), and your fibula (the thinner bone on the lateral portion of your lower leg).
The tibia should be able to rotate without pain, and without compensation from the femur or ankle. Check out the video below to see the tibia in motion the way it is built to move, then try moving your tibia.
Tibial internal rotation is important for promoting proper meniscus motion and for supporting dynamic movements like changing directions, cutting, or pivoting (you don’t have to be an athlete to do these movements, even every day versions of them require tibia rotation).
Tibial rotation is valuable to maintain (or re-gain) whether you’ve had surgery on your knee, or not.
Another interesting tidbit about tibial rotation is that the lack of it influences how much movement freedom you have in your knee. From this excellent post by Dr. Michael Chivers, a peer I admire greatly,
“The dynamic lack of tibial internal rotation will limit somatosensory input from the knee altering control strategies and synergies which will impair the athlete’s ability to adapt to constraints, reduce the necessary degrees of freedom and trap the knee into a state of low coordinative variability. The literature on post op ACL patients shows that this impaired feedback from the knee leads to a noisy and unpredictable system kinematically and implies more rigid behaviour the long term consequences of which can be detrimental to returning to previous levels of sport and can lead to undesirable future consequences.”
You want your knee to be able to adapt to constraints, to be free to move, and to be well-organized and controlled in how it moves. Lack of tibial rotation impairs that.
Your patella is the largest sesamoid bone in your body, which means it is a bone embedded within a tendon or muscle, in this case, it’s the quadriceps tendon that the patella is embedded in.
Your patella should be able to glide in all directions fairly smoothly, without pain. Check out the video below of Dr. Andreo Spina moving the patella the way it is built to move, then try moving your patella.
When is the last time you checked that your patella could do that? The thing is, your patella should be able to do that. If it cannot, you’re likely to see compensations and adaptations that can lead to biomechanical issues, degenerative changes, and pain.
Your knee joint is built to flex, so that the calf can come all the way to the back of the thigh easily and without pain. This is valuable range of motion to have not only so that you can sit on the floor with your shins tucked under you, but also so that you can walk, run, go up stairs, go down stairs, and do workouts or activities you enjoy.
Check out the video to see knee flexion in motion the way it is built to move, then try moving your knee into flexion.
When you cannot move into full knee flexion, several things can occur, including:
- decreased neural drive to the hamstrings
- reduced external force that needs to be placed on passive tissues of the knee joint (meniscus, ligaments, tendons) in order for them to be grow, strengthen, and turn over healthfully
- Alterations to hip and ankle mobility as they attempt to make up for what the knee is no longer doing
Your knee joint is built to extend, so that you can completely straighten the knee joint into what is called ‘terminal knee extension’ (TKE), which is approximately 5° past “neutral”/fully straight.
Check out the video to see knee extension in motion the way it is built to move, then try moving your knee into extension.
Terminal knee extension is a crucial piece of range of motion to maintain or restore, and loss of TKE can create all sorts of issues, including:
- becoming unable to disperse load across the joint and thus overloading some aspects of the joint cartilage and underloading others
- altered angle of pull on the patella, which can create inflammation in and around that area
- loss of optimal quadriceps force production
- Increase of lumbar extension to compensate for lost hip extension
Not only can these issues create pain, they disallow optimal function and movement of the lower body.
Does Your Knee Work Like A Knee?
First thing to remember if you have discovered that your knee doesn’t do all of the things that knees are built to do is this:
You’re not stuck like that forever. Your body is always receiving the signals you send it, and responding accordingly.
Like I instruct my beginners, it doesn’t have to be complicated in order for you to get started, in fact, better that it’s not.