What the Femur?

👣 In this series I’ll discuss the femur’s relationship with the pelvis, I’ll explain the difference between terminal extension and hyper extension at the knee , I’ll let you know why we don’t really enjoy internal rotation of the hip AT ALL, and how all of this can lend itself to your back pain. This all becomes clear in my Closed Chain Biomechanics of the Human Body in Motion online education courses.

The femur – foot relationship

👣  The femur itself is the longest bone in your body and forms the link in the chain between your pelvis and your shin bone. Between the pelvis and your femur is the hip joint. This is the articulating space between the two structures. Between the femur and the tibia is the knee joint. The hip operates in three dimensions and the knee strictly operates in only two. The dimensions are explainable through the articulating surface of the joints where the structures meet. The hip joint is much more free, mobile and rangey with it’s ball and socket arrangement than the knee which is limited to a bending and straightening with either an internal or external rotation.

👣 The femur itself has in my opinion a cute relationship with the foot. This may not be obvious given that it is one whole bone removed from the foot. The tibia or shin bone sits between the two AND YET an interesting consistency occurs between the foot and the femur, with one certainly impacting on the other.

👣 When a foot pronates, or flattens (educate yourself more on what this means in my Wake Your Feet Up programme) the femur always rotates internally (this is for the thigh bone to rotate inwards toward the midline of the body). When a foot supinates, or increases in arch height, the femur always rotates externally (this is for the thigh bone to rotate outwards away from the midline of the body)

👣 Given that the vast majority of people spend their life in a pronated foot posture, this tells us that most people’s femurs will already be resting internally rotated. If you cannot supinate the foot well, the femur will struggle to rotate outwards – this is a key movement for health of the pelvis, hip joint, knee, flow through the femoral triangle (arteries and nerves etc). Likewise if your struggle to externally rotate the femur, the foot will lack the ability to supinate and get you out of your pronated posture.

Relationship with the pelvis

👣 Above I touched on the foot’s relationship with the femur. When it pronates or flattens, the femur (thigh bone) rotates internally. When the foot supinates or increases in arch height, the femur rotates externally or outwards.

👣 Something else to pay attention to here is when the femur rotates internally it creates the conditions for an anterior tilt (AT) of the pelvis: this is where the pelvis tips forward creating an arch in the low back; when the femur externally rotates it creates the conditions for a posterior tilt (PT) of the femur – pelvis tips back and down.

👣 We can now link, by following the chain, a connection between the foot and the pelvis. Foot pronation > anterior tilt of the pelvis and foot supination > posterior tilt of the pelvis.

👣 If your foot is flat and you find that you can’t posterior tilt your pelvis, this could be why (you will have tested this if you have sampled my Wake Your Body Up programme). It might also explain why you can’t anterior tilt your pelvis since the flatter your foot, the more internally rotated your femur will be and the less space to anterior tilt into you will have.

👣 Something a lot of people will try to do is to anterior and posterior tilt their pelvis without consideration of the femur. The two need to move together. Add the foot into this arrangement and all of a sudden it becomes a lot to consider, and to be inconsiderate of these things highlights how you can remain stuck in the same pelvic posture for years on end. 

👣 Are you the type of person who’s pelvis slips forward in space over their forefeet? If so you will find that your pelvis is neutral or posterior tilted, this forward send of the pelvis naturally rotates the femurs externally. Interestingly this posture is usually on somebody who’s feet are pronated (flat) where the tactic, if you like, of placing the pelvis in this position reduces the internal rotation of the femur and therefore minimises any further pronation of the foot. In this case the external rotation of the femur encourages foot supination as a way of minimising foot pronation. Hope that makes sense? If the foot is pronating, and the pelvis is posterior tilting, we have a problem as the two movements do not connect together in a flow, therefore one is blocking the other – this scenario always leads to a reduction in the movement of all the structures involved. The system has to be working together in order to optimise movement; in this case to be able to both anterior and posterior tilt the pelvis, internally and externally rotate the femur and pronate and supinate the foot.

👣 This system has to be working together in order to optimise movement. You may have spent years trying to supinate the foot. Did you pay attention to your pelvis and your femur at the same time? You may now have begun to look at improving pronation of your feet. In doing so are you paying attention to the femur and the pelvis at the same time?

👣 The joint surfaces create the movement. They either all do what they should or they don’t. If we are in the “they don’t” space, then it’s time to ensure that they can begin to experience movement, increasing the range at each structure, not individually but as an integrated whole.

Internal rotation – and why we don’t really enjoy it

👣 I’m not one for writing controversial posts… but some of you might find this to be controversial. Since so many schools of thought exist around the requirement for improving hip internal rotation. I just want to state that this is something I would never do. The reason being that the hip itself doesn’t actually enjoy internal rotation. You should try it. And When I say try it I mean try to achieve an ACTUAL hip internal rotation in the closed chain – with your foot on the ground and the whole chain taking part in this hip IR.

👣 So, the only way to truly achieve a closed chain hip internal rotation is to pronate (or flatten) your foot, this internally rotates the tibia, internally rotates the femur and in turn there will be a desire for your pelvis to simply rotate away from this foot. However this would create an external rotation at the hip joint. So instead what I would like you to do as you pronate the foot (let’s say the right foot), I would like you to rotate the pelvis to the right at the same time. You will notice that you pinch right up in side that hip immediately. You don’t have to travel very far to make this happen. There literally is very little room to rotate your hip internally. If anyone turns up in this posture, it’s likely they will report discomfort on the inner part of their groin. What I am saying is not an opinion, you can actually feel it.

👣 As previously mentioned, this is exacerbated by the fact that you may be one of the 95% of people who’s feet are more pronated than not, in which case your femurs are already internally rotated. How is improving hip internal rotation going to be of benefit in this scenario? For those of you who enjoy an internal rotation test, say laying a patient on their back and manually rotating the legs inwards, you might find that one leg just doesn’t roll in as much as the other. This might not be an indication that they cannot internally rotate their hip BUT THAT THEIR FEMUR is already internally rotated. Stand them up check the foot for pronation, the femur for internal rotation and the knee to see if it is flexed or experiences hyper extension (more about the knee below).

 

👣 In gait, as observed in the creation of my Flow Motion Model™, you NEVER EVER see the hip joint experience an internal rotation. The femur internally rotates, but always with an external hip rotation and on the occasions where the hip does actually internally rotate it’s always rotating from an externally rotated position back to a neutral point and never actually enters the arena of a true internal rotation.

👣 To complete this idea, when you internally rotate a femur it always rotates the pelvis away from itself in the closed chain (upright and in motion) and when you externally rotate a femur it always draws the pelvis towards itself in a rotation. The femur should never rotate towards a pelvis that is rotating towards the femur – that causes a true internal rotation and IS NOT A COMFORTABLE POSITION IN YOUR BODY. If you are doing ‘open chain’ hip internal rotations, it’s unlikely that you really create a true internal rotation, so this is quite a safe way to do it… but I do often wonder if there is any actual point. If you are attempting this in the closed chain, it’s my strong suggestion that you don’t try too hard – especially if you have pronated feet and internally rotated femurs.

The Femur and the knee

👣 Above, I dropped a bomb and claimed that we don’t like hip internal rotation and yet it is something that is preached and hailed in both the fitness and therapy industry. When femur’s rotate internally they push the pelvis away which actually creates a hip external rotation in the closed chain. When you rotate your pelvis towards your femur, thinking you are internally rotating your hip, you are actually pushing the femur into an external rotation, reducing the amount of hip internal rotation you can achieve.

👣 In this scenario there is also unsurprisingly an impact at the knee. If you rotate your pelvis to the right, when standing up, you should notice that your left knee naturally enters into a knee bend. This is because the left femur rotates internally as a result and connects down to the foot which must pronate (flatten), so we can equate foot pronation and femur internal rotation with knee flexion (or bending). At the same time you should notice that the right leg begins to straighten. This is because the right femur rotates externally as a result of the pelvic rotation and connects down to the foot which must supinate (increase in arch height), so we can equate foot supination and femur external rotation with a knee straightening or extension. The problem now becomes if you can or cannot supinate your foot and externally rotate the femur. 

👣 If you lack external rotation in your femur, you will not be able to achieve what is known as a terminal extension of the knee. An actual full extension of the knee that creates a locking between the femur and the tibia and ultimately a straight leg. Most people are trying to straighten their leg on a pronated foot (or an anterior tilted pelvis) with an internally rotated femur. This is not a good idea since one of two things can happen: either the knee will not be able to straighten, since femur internal rotation is a precursor for a knee bend on a pronated foot OR the knee will enter a hyperextension (extending beyond a straight position) thanks to the internal rotation of the femur and the inability to supinate the foot.

👣 If you have a knee hyper extension, it is because your femur does not externally rotate (and most likely neither does your foot). Again this is a highly controversial subject, and yet there is a distinct difference between a straight leg and a hyper extending knee. If you cannot externally rotate your femur, you will have difficulty straightening your knee correctly. Promoting femur internal rotation with the straightening of the knee is a recipe for disaster in my book. 

👣 Technically if you are thinking about weightlifting and dropping into a squat, you can bend the knee with your femur externally rotating by sending your knees out towards your little toe, the requirement to enable this to happen is for the foot to supinate, if you struggle with that, the femur will not XR, the knee will bend regardless and you’ll recognise the fight between pushing your knees out and your feet trying to roll in!

👣 So far we have seen the femur relating to foot pronation and supination, to pelvis anterior and posterior tilt and to knee flexion and extension. Probably a useful thing to consider in both our own movement and the observation of other’s movement too.

External rotation and what it tells us

👣 So in the context of “What the Femur” what’s actually missing in our life is most likely femur external rotation which couples with foot supination and pelvic posterior tilt. This hopefully makes sense when the majority of people find themselves anterior tilted with pronated feet and a resultant internal rotation of the femur.

👣 The hip joint itself has way more access into external rotation than internal rotation as I alluded above. Oddly in gait, external hip rotation occurs when the femur rotates internally, this creates the conditions for a pronating leg shape. Foot pronation / knee flexion / femur internal rotation / anterior tilt. What we really want to be able to access to pull us out of this shape is the opposite movements. Foot supination / knee extension / femur external rotation / posterior tilt. This forms a straightened supinating leg that will efficiently drive us forwards and into our next step. It will also take the pressure off our pronated feet, our bunions, our neuromas, our plantarfasciitis, our medial knee pain, our piriformis discomforts.

👣 This is because human movement is always about being able to access both ends of the movement spectrum. If your femurs are internal and can’t go external (supinating the foot when they do), then you are going to struggle to straighten your knee and open up the anterior part of your hip with a posterior tilt. So you remain valgus, knock kneed, flat footed and anterior tilted. That is not to say that these movements are bad, we need them, we need all movement capabilities as to be able to have both: to internally and externally rotate the femur, to anterior and posterior tilt the pelvis, to flex and extend (correctly) the knee and to pronate and supinate the foot, is the true definition of movement.

👣 This is what your skeletal system craves and has most likely forgotten how to access. You normally focus on one thing or the other thing rather than creating the opportunity to focus on multiple things all at once. It’s easier to do the former, I get it, but in the human body it does not make sense. All movements in the human body require each other.

👣 So next time you think about supinating your foot, think about making sure the femur externally rotates – put your hand on it, feel if it rotates outwards with you or not.

👣 Next time you pronate your feet, make sure the femur internally rotates – put your hand on it, feel if it rotates inwards with you or not. Next time you check your anterior tilt, make sure the femur internally rotates – put your hand on it, feel if it rotates inwards with you or not.

👣 Next time you posterior tilt your pelvis, make sure the femur externally rotates – put your hand on it, feel if it rotates outwards with you or not.

👣 Next time you bend your knee, make sure the femur internally rotates – put your hand on it, feel if it rotates inwards with you or not.

👣 Next time you straighten your knee, make sure the femur externally rotates – put your hand on it, feel if it rotates outwards with you or not. 

👣 Want to delve further into this concept? we have self-assessment programmes called WAKE YOUR BODY UP and WAKE YOUR FEET UP and an online education programmes called Closed Chain Biomechanics of the Human Body in Motion.

Femur and back pain

👣 Low back pain can come in a variety of forms, there can be SIJ pain, compression in the lumbars on one side or the other, or tension in the lumbar tissues arising from the resting posture of the structures.

👣 This internal rotation of the femur has that direct impact on the pelvis to encourage an anterior tilt. The anterior tilt of the pelvis forces the ilium bones of the pelvis to compress forwards onto the sacrum. The joint between the ilium and the sacrum is known as the SIJ (sacroiliac joint) and is what can be being compressed in this environment.

👣 This anterior tilt in the pelvis also creates an extension or increased lumbar curvature in our low back. The greater the increase in the lumbar curve, the more compressive forces are placed upon the posterior parts of the intervertebral joints. This compressive force can often be a source of discomfort for people. When you then couple this with a rotation in the pelvis and therefore a rotation in the spine (for a rotational outcome at the pelvis one femur must be more internally rotated than the other and one foot more pronated than the other; and/or a side bend to one side perhaps through a weight shift, this would increase the forces running through the low back. Is it the back’s problem? No it’s a whole body problem.

👣 So once again, foot pronation leads to the IR of the femur, which creates an environment for both the pelvic anterior tilt and a knee flexion (or hyper extension). To resolve all of this, we always come back to what’s missing?

👣 Can you both internally and externally rotate the femur? Anterior and posterior tilt the pelvis? Pronate and supinate the foot? And can you do all of that together in one sequenced motion? That’s when things get really good, when we expand our focus from one part to many parts. And that is the focus of our self-help programmes to help you take ownership of your own body through understanding and education – the content of which is all underpinned in my Closed Chain Biomechanics of the Lower Limb course, our online education course that introduces you to a very detailed look at the bones, joints and muscles of the lower limb to lay the foundation for future learning with us here at AiM. 

👣 Sometimes as mentioned in this series, the pelvis shifts forwards in space, externally rotating the femurs and I talked about this being a tactic to minimise further foot pronation. The external femur puts a supination motion into the foot to counter its need to pronate – but at the same time clams everything up to the point of minimal motion. This forward shift of the pelvis also creates increased lumbar curvature as it leaves the ribcage behind and yet again we have created an environment for lower back discomfort – not everyone like this has lower back discomfort but if they have you might want to consider helping them (for yourself) to undo that.

Common Question / Answers

Question: At rest (lying on my back) my right foot turns out more than my left. Is this my body’s way of compensating by having a femur more rotated to the right because my foot struggles to pronate?

Answer: Thanks for asking this great question. In a nutshell your leg appears to rotate externally to give you more access into pronation. It is a very clear indicator that you need to improve the quality of pronation in this foot. Interestingly as you follow the foot up – you think the femur is rotated externally – but in actual fact your femur will be more internally rotated than your tibia which will be more internally rotated than your foot. The foot turn out is the real external rotation here. The external rotation you are seeing will either be at the hip and could even be at the knee. Our clever bodies turn our feet out to benefit from more pronation. So if we take that as guidance from our bodies, we can work out that the more turned out foot wants better pronation, and so it’s a good idea to give it that opportunity. Hope this is useful. Gary

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