When I first began training (many) years ago, the first correlation in the body that might sense was the way the hip influenced the knee. It seemed like common sense that the femur, which spans the acetabulum to the tibia, would affect how the knee moves through space. (I was a little slow to realize similar connections can be made wherever a bone exists between two joints, but I got there eventually). It took me a while, more accurately, several years, to fully appreciate more fully how the knee dynamically functions during movement.
The knee cap, aka the patella, is a sesamoid bone that attaches to the trochlea of the femur (1). Stability is provided via the patellar tendon, joint capsule, and ligamentous structures.
The tibia, or shin bone, doesn’t connect directly to the patella, but it does connect to the tibia (2). The knee joint is considered the articulation between the femur and tibia and the patella and femur. It is a hinge joint that allows some rotation when flexed.
There are also several ligaments provide stability at the knee joint. The tibial collateral ligament and the medial patellofemoral ligament provide stability medially, while the fibular collateral ligament and the IT band provide stability laterally (1,2). The PCL and ACL form an x to prevent the knee from hyper flexing or hyperextending. There are also menisci, flat, crescent shaped discs comprised of fibrocartilage that absorb shock and attach at the intercondylar portion of the tibia.
When we walk, there is a moment after our foot lands that it moves into pronation. This sets off a chain reaction all of the way up into our pelvis. At the knee, it is estimated about 70% of the force is directed through the medial compartment (3). Before you imagine knees collapsing inward and eventually wearing out due to this force, remember there are muscles, specifically the quadriceps, hamstrings, gastrocnemius, and TFL that counteract the adduction moment and keep everything from coming completely unhinged (4).
It’s important to remember we aren’t all put together exactly the same. When you consider our anatomy as well as our habits, it shouldn’t come as a surprise researchers in India found significant variation in the tibial plateau angle, the area of the tibia which articulates to the femur (5). Variations like this cause movements like knee flexion or extension to look different between individuals; variation is not an indicator of dysfunction.
Locking the knees:
Remember how up above I talked about the ligaments preventing hyperextension? While this might not be indicative of pain, any time someone bypasses muscular effort and uses the ligaments for postural support instead, the long term effects might be an issue. (Or it might not. A 2013 paper points out joint hypermobility as a predisposing factor for ACL injury is controversial (6)). What we do know is teaching people to use muscular effort, rather than ligamentous effort, during activity aids in proprioception, which improves coordination, which at the end of the day makes things more efficient.
This isn’t to say that knee extension is bad; I work with a couple of people who were told to soften their knees for so many years, they don’t have the strength (or confidence) to fully straighten their knees. Think of the arm- we can all agree the arm should be able straighten fully with muscular effort. The same is true of the knee joint.
The knee joint enjoys another wives tale regarding the amount of force it can withstand during a squat. There was a 1982 that showed patellofemoral forces during a squat were between 4.7 and 7.6 times an individual’s bodyweight (7). Another well known paper, published in 2001, concluded healthy individuals shouldn’t squat below 90 degrees “because injury potential to the menisci and cruciate and collateral ligaments may increase with the deep squat,” (8).
At this point, most fitness professionals understand the knee is meant to bend and as long as tissues are exposed systematically. Recent researchers have thrown the whole, “squatting is bad for your knee” theory out with the bathwater. A 2013 review of the research found no evidence supporting the theory that deep squatting is harmful to passive tissues (9). (Plus, squatting is hip flexion, knee flexion, and ankle dorsiflexion. If you have these three things, you can squat with relative ease.
Training clients with knee pain:
Let’s take a look at how to work with individuals that have knee pain. It can stem from a minor meniscus tear, or maybe it falls into the catch-all category of “patellofemoral syndrome.”
Research suggests things like torn menisci don’t always require surgical intervention (10). This is sort of amazing, since I told you earlier those particular structures are responsible for cushioning and stability. Yet the knee (like all parts of the body) is capable of finding work arounds. Muscles and tendons can be strengthened and provide support in a similar way.
I’m not writing this to suggest surgery is never indicated; only a doctor (or three), can determine that. I am sharing this with you so that if someone comes in and tells you she has a partial meniscus tear and decided not to operate, you don’t panic and worry about her fragility.
Back to the knee. Let’s assume (because it’s easier) the hypothetical client has general knee pain. It’s uncomfortable to deeply bend, kneeling positions don’t feel great unless there is extra padding between the knee and the floor, and, to add insult to injury, the doctor says there really isn’t anything wrong. For a little context, the individual is 49 years old, not very active, about 20 pounds overweight and “stiff as a board.” What do you do with her?
Here’s the deal. If you put this person into a situation where you ask her to squat or lunge right away, her knee will hurt. Almost guaranteed. Why? Because the client is scared to bend the knee. So if the first (or second) thing you do with this person is try and have her do the very thing that she is certain will cause her knee to explode, there will be muscle guarding, fear, and generalized discomfort afterwards. In addition, it is possible the way she achieves a lunge or squat motion could be approved upon or altered in a way that minimizes knee discomfort.
Instead, work on hip mobility and ankle mobility. Supine ninety/ninety (with the feet on the wall) is a great place to start. You can teach the person how to feel the wall with the feet and what it feels like to flex at the hips while maintaining awareness at the pelvis.
“But wait!” you might be thinking. “Isn’t supine 90/90 just a squat on your back? And didn’t you just say not to squat?”
Yes, which makes it an excellent way to introduce the idea of hip and knee flexion in a place that feels “safe.” It’s also a great way to work on rib cage position. You can even have the person actively hang out there while performing an upper body exercise, turning a mobility/awareness exercise into a way to improve strength. (I am all for multi-tasking).
Typically, with knee pain clients I see one of two things happen at the hip. The first is a bias towards external rotation. When you place these individuals in supine 90/90, they will set up with their feet turned out a little bit and/or the weight will primarily be in the pinkie side of the foot, their hips externally rotated. If I get the person to ground through his feet by dispersing the weight through the ball of the foot so the big toe is pressing into the wall as well, this will change the person’s experience. Often, he will begin to feel work in his adductors, especially if I cue any sort of awareness through the front of the pelvis. For these individuals, I will often cue “pretend like your two front hip bones are coming towards each other. (I have one client for whom this cue eliminated her knee pain. If she ever feels her knee while walking, she thinks about this and her knee pain goes away. She has a torn MCL and decided to skip surgery. It’s amazing what a change in perspective will do). I sometimes cue the arch of the foot pressing towards the wall as wall if there is a lot of rigidity in that area. (There are a lot of drills I use for the foot, which I covered in a previous post).
The second bias I see is towards internal rotation. These individuals appear knock-kneed. When I place them on the wall, I see if I can get awareness on both sides of the foot (there tends to be a little more weight towards the arch). If the arch is flat, I might use a few tricks to wake that area up.
Next, I work to get external rotation at the hip. This is different than abduction, though they work together. I teach it by having the person take his hands to his outer thigh and gently rotate the skin out. I then have the person remove his hands and mimic the same sensation. Usually, this will cause an increased awareness in the lateral hip or quadriceps area.(Make sure the person has a good connection with the ribcage and the pelvis).
Both of these drills improve awareness and give alternative movement options. Once we have done this a few times, I might work towards standing up and sitting down with out hands, cueing the same sense of the foot. *Usually,* this works really well. Clients don’t deem the movement threatening because they do it all of the time. The focal point placed on an area other than the knee generally works well.
Notice I didn’t mention whether or not I coach the feet in parallel. Sometimes parallel causes pain. If this is the case, I tell the client to turn out one (or both) feet so that there isn’t any pain. Or I widen the stance. Or narrow the stance. I give people permission to find the option that works for them. I add a little bit of guidance in the way of suggestions, but in the 15+ years of training clients, I have always been able to find a position that allows people to get up and down off of a bench (multiple times), eventually with weight and away from the bench, pain free.
Also, I find that doing a lot of awareness work at the foot and the ankle allows people to (eventually) move towards a more parallel stance. Cues like, “spread the floor with your feet,” “reach your heels away from each other,” or “pretend like your arches are pulling towards each other” all change what the person experiences. (Which cue I use is dependent upon what I am trying to teach).
At some point, straight leg raises were vilified as a less than useful exercise. I disagree. I use supine straight leg raises to teach hip flexion. Frequently, knee clients are either a) scared to straighten their knees or b) prone to hyperextension. Supine straight leg raises are a nice way to teach hip versus knee movement while keeping a straight, but not locked, leg.
Another tool I use is supine knee flexion. Sometimes I use a strap, sometimes I use hands at the back of the thigh for feedback. Examples of both of these drills can be found here. You would be amazed how many people think that in order to flex their knee on their backs, the need to flex their hips. This very basic drill begins to separate knee movement from hip movement.
We can also flip it over and look at prone knee flexion. In the last two years, I have worked with two people that really wanted to be able to do dancer’s pose, a yoga pose involving a lot of extension. Stuck in the middle of all of that extension is knee flexion. Having the strength to flex the knee makes the rest of the posture easier.
One of my favorite ways to work on knee flexion is shrimp squats without holding the back foot on the way down. It is harder than it looks, and turns up the volume in the hamstrings.
Finally, hip mobility and strength make a huge difference in what a person experiences in his knees. The GMB hip mobility sequence below here is one of my favorites when I am short on time.
Your knees are designed to last for a long time, over many miles. Keep the structures surrounding them strong, mind your feet, and isolate your hips for many years of happy knee bending.
*Spots are filling in the June 2-4 Napa Valley Nature and Movement retreat. For more information or to register: http://www.bewellpt.com/events/2016/9/11/mind-body-nature-a-two-day-movement-retreat
Your in health and wellness,
Loudon, J.K., (2016). Biomechanics and pathomechanics of the patellofemoral joint. International Journal of Sports Physical Therapy, 11(6), 820-830.
Moore, K.L., & Agur, A.M., (1995). Essential Clinical Anatomy. Lippincott Williams & Wilkins: Philadelphia.
Hurwitz, D.E., Sumner, D.R., Andriacchi, T.P., & Sugar, D.A., (1998). Dynamic knee loads during gait predict proximal tibial bone distribution. Journal of Biomechanics, 423-430.
Windy, C.R., & Lloyd, D.G., (2009). Muscle and external load contribution to knee joint contact loads during normal gait. Journal of Biomechanics, 42(14), 2294-2300.
Medda, S., Kundu, R., Sengupta, S., & Kisor Pal, A., (2017). Anatomical variation of posterior slope of tibial plateau in adult Eastern Indian population. Indian Journal of Orthopedics, 51(1), 69-74.
Vaishya, R., & Hasija, R., (2013). Joint hypermobility and anterior cruciate ligament injury. Journal of Orthopedic Surgery, 21(2), 182-184.
Dahlkvist, N.J., Mayo, P., & Seedhom, B.B., (1982). Forces during squatting and rising from a deep squat. MEP, 11(2), 69-76.
Escamilla, R.F., (2001). Knee biomechanics of the dynamic squat exercise. Medicine & Science in Sports & Exercise, 127-141.
Hartmann, H., Wirth, K., & Klusemann, M., (2013). Analysis of the load on the knee joint and vertebral column with changes in squatting depth and weight load. Sports Medicine, 43(10), 993-1008.
Shivonen, R., Paavola, M., Malmivaara, A., Itala, A., Joukainen, A., Numi, H., Klaske, J., & Jarminen, T.L.N., (2013). Arthroscopic partial meniscectomy versus sham surgery for a degenerative meniscal tear. The New England Journal of Medicine, DOI: 10.1056/NEJMoa1305189