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Knee Injuries

We recently ran an anatomy workshop for Yoga Instructors with Meadowlark Yoga.  I ran a session on the most common injury in Yogis; left knee medial meniscus tears. It had such fantastic feedback that I thought I would repeat it here to help spread the message further.  Obviously it is here without the cadaveric specimens but I hope the drawings and your imagination can fill the gaps.

 

The most common injury in Yoga people in left knee medial meniscus tears.  Why should that be?  I’m hoping that if I explain a little of how the knee joint works you may be able to work out what the problem is and what can be done to mitigate it.

The knee is the most complex joint in the body.  You only have to look at the diagrams to appreciate all the tendons and moving parts that make up the joint.

To keep it simple, the joint is not a hinge joint as it is often described. The articulating surface of the femur is a lot larger than the articulating surface of the tibia in the lower leg.  As the joint hinges it also has to slide to ensure these surfaces stay in contact with each other.  It is the role of the cruciate ligaments, both anterior and posterior, to ensure that the femur does not slide too far in either direction

To further increase the surface area at the top of the tibia we find two semi circular shaped cartilage wedges (thicker at the edge of the knee, so almost triangular in cross section).  These increase the surface area and also help to hold the femur in place on top of the tibia.

These semi circular wedges are the menisci, one lateral – to the outside of the knee, and one medial – towards the inside of the knee joint.  As you can see in the diagram above, the lateral meniscus is not connected to the ligaments at the side of the joint and so it is held in place only at the two end of the C shape.  It can move around more easily inside the joint than the medical meniscus which is joined to the ligament at the inside of the knee joint.

As the knee flexes (foot moved towards your bottom) the menisci move to the back of the joint. If your knee is fully flexed then your menisci are quite safely held at the back of the joint.  How many people do you know who can get their foot all the way to their bottom?  If your leg isn’t fully flexed then the menisci are in the process of moving backwards.

The knee isn’t only a sliding hinge joint, it also has a degree of rotation.  If you have a straight leg and rotate the limb then all of that motion is coming from the hip.  If you now bend your leg you can get a few degrees of rotation at the knee joint.

If you medially rotate your lower leg, turn your big toe in towards the centre of your body then this will cause the medial meniscus to move forwards and the lateral one to move back.  Just pause for a moment and imagine the two bones on top of each other, rotating and you can see what would happen to the menisci if they are just held at the end of their C shape.

Now imagine what you are asking your knee to do if you medially rotate your lower leg whilst also flexing your knee joint.  This is the equivalent of reaching down, grabbing your foot and lifting it up towards your stomach, something you see quite a lot in an exercise setting.  The flexing motion is asking your menisci to move back and the medial rotation is asking your medial meniscus to move forwards.  You are trying to move the same piece of cartilage in two opposite directions at the same time!

So why left knee injuries?

It’s traditional to go into the lotus pose in yoga with your right knee first.  This means to bring the left knee into this pose you have to lift it over the right leg that is already in position.  It doesn’t matter how flexible you are – that is an impossibility.  The result, you are twisting a not fully flexed knee.  It is a potential risk for the meniscus.

What can you do to help it? Don’t do lotus or if you are not prepared to go that far – or you can’t do lotus anyway so you want to know how to protect your knees for other poses – try to laterally rotate your lower leg if it isn’t fully flexed.

Rather than reaching down and grabbing your toes, reach underneath and grab the heel.  Ensure that if you move your lower leg at all that the toes would rotate outwards rather than inwards.

I’ve written about anatomical issues with the lotus position for yoga moo if you want to see the article on hip rotation than click here

 

 

Lost in translation

How often have you heard something and thought that maybe the message has lost something in translation.  It’s a challenge in communicating to people about how their body works.

I have spoken before about how when you raise your arms above your head, you need to rotate the arm otherwise a lump of bone at the top of your arm bone (humerus) bangs into your shoulder bone (scapula) and your shoulders end up around your ears.  For years exercise instructors would tell people to correct this by pushing their shoulders down not realising they were asking them to do something anatomically impossible.

I was treated to an excellent example of this message getting corrupted last week.

In an exercise class, the instructor asked us to take our arm above our head.  The way we had approached this in the class meant that our arm was actually rotated anyway.  Then they added to not forget to rotate your arm so that your shoulders stay down.  At this point they then spun their hand over to face in the opposite direction.

Where to start?

Clearly they had heard about the shape of your arm bone affecting your shoulders.  Great!

They didn’t remember what side the lump of bone was (or maybe weren’t told) and so were suggesting the arm be turned the wrong way.  Not so great.

They rotated their hand to correct the problem. Doesn’t work!

Why doesn’t it work?

Your forearm is a master piece of engineering that can place your hand in a wide range of positions.  That is really the whole point of the arm; to position the hand in space.

You can turn your hand through almost 360 degrees.  This is achieved by a combination of shoulder rotation and a twisting action at the forearm in a movement called pronation or supination (depending which way you go). Supination is when the palm is facing up in a way you could put soup in it.

 In anatomy we have this position called ‘anatomical position’.  This is someone standing up with their hands by their sides and their palms facing forwards.  Anything towards the mid line is called medial, anything towards the edge of the body is called lateral.  Your thumb is lateral, your pinkie is medial.  Doctors use this language to ensure they are talking about the same part of the body.  It does not matter the position you are in, everything is referred to as if it were in the anatomical position.  Your thumb will always be lateral, even if you turn your hand around.

As you can see from the image, pronation and supination are movements that happen around the elbow joint – its actually a little joint at the side where the two bones in the forearm meet each other.  The radius (the lateral bone on the thumb side of your forearm) can rotate around the other bone (ulna) allowing the hand to face in the opposite direction.

So, we get in to position in the class and then flip our hand around to face the other way.  has it had any effect on our shoulder? No.

Has the instructor covered enough anatomy to know that was going to have no effect on the shoulder?

Does it matter?  Maybe not, but it is fairly fundamental.  You can’t look after your body to the best of your ability of you don’t know a little bit about how it works.

 

 

And on that Note

Last week I was at a concert (how on earth is she going to relate this to anatomy?)

Whilst the way in which we hear is fascinating and complex, I actually wanted to talk about public engagement and getting your message across.

We have all heard the message about how you should lift with your legs, keep your back straight and bend at the knees and hips.  It must be one of the most prominent messages about people’s anatomy, and yet, does anyone ever listen to it?

I watched as the young people cleared away the instruments.  This included lifting several heavy percussion instruments onto a stage that was about three foot high.  One of the lifts involved 8 people.

The kid at the left hand end was the only one that I saw keeping a straight back and lifting as instructed. (This is because he has had anatomy forced upon him at home)

Some of the lifting techniques being displayed were truly wince inducing and I’m sure they will be making physical therapists wealthy for a long time to come.

Why are we so bad at taking in messages that are meant to do us good?

It is the eternal battle of public engagement.  Engage without preaching. Make what ever it is fun and relevant.

Anatomy should be so easy to make relevant – we all have it.

As we enter the International Science Festival I wonder if we will be able to get our message across any better than those people who deliver manual handling courses.

 

 

Sum of your parts

sum

I was recently struck by a phrase in BBC’s silent witness.(This is not unusual, I have friends who work in forensics, I am often bombarded with phrases about silent witness, although I note that it is now much clearer that they are an independent lab and not part of the police force.  Do we sub contract out forensic investigations? – I digress)

 

The phrase was said whilst watching a post mortem when a body is reduced to weights and measures and it was ‘that we are so much more than the sum of our parts’

Never is this more true than in the case of Neuroanatomy.  We take a mass of grey and white cell matter and we divide it into areas, we name things (in fact, being anatomists we name things several times over; is that your putamen or your lentiform nucleus?)

We identify pathways we draw on areas but when it gets down to the fundamentals, we still aren’t sure how it works.

It’s great to get the opportunity to make people stop and wonder about the body that they are living in.

I recently had a conversation with some students about reflex arcs.  They had drawn out a lovely team diagram of a reflex arc showing a hand being pulled away from a flame. They clearly understood it and were finished earlier than the other groups.  How to keep them occupied?

Do you want to draw out the diagram for standing on a LEGO brick?

There was almost an audible tut, a few minutes later they had drawn out exactly the same diagram replacing the hand with a foot.

That’s great! Is that what actually happens?  You walk across the room, stand on a LEGO brick and lift your foot directly up?

‘No, you usually stumble a bit and swear.’

Ok, why do you stumble? What would happen if you just lifted one foot directly up?

‘You would fall over.’

Exactly, so what else has to happen?

‘You must tighten up the muscles down here’, ‘but wait you stumble so you must loose your balance.’  ‘It must go up to the cerebellum!’  ‘But how do you know you’ve lost your balance?’  ‘It must have inputs from the eyes and ears.’  ‘But wait, you swear, it must involve the speech areas.’ ‘Do you need to double check it’s appropriate to swear, do we need a feedback loop in there?’

Their diagram expanded, it drew in things they had learned about weeks before.  It had gone from a simple little loop to a series of pathways that all happen in the blink of an eye and all subconsciously.

We are so much more than the sum of our parts.

New Year Resolutions

How are you doing with your New Year Resolutions?

I have a friend who is doing really well with hers.  Its a bit unusual.  She decided to take up alternate nostril breathing.

As the name suggests this is breathing through alternate nostrils.  Usually the other one is held shut with your fingers.  It’s a yoga technique and you can read a lot about which fingers you should use to shut the other side of your nose and the benefits of the technique.

There is no doubt it works.  No one knows why.  There is no scientific evidence for any of the effects (I’m not sure anyone has really looked).

It claims to calm you down, reduce stress, make you more mindful, stimulate your nervous system and reconnect the two hemispheres of the brain.

I’m not sure about the last two.  The two hemispheres of my brain are connected quite well by the corpus callosum and doing anything stimulates your nervous system – that’s the point of it.

I suspect the other benefits might well be brought about by sitting quietly and thinking about your breathing – whether you are using one or two nostrils.

I ran a workshop on breathing last year.  We didn’t do any fancy exercises, I simply explained how breathing works; what bits are designed to move etc.  The participants managed to reduce their breathing rate from 12-14 breaths a minute down to around 4.  If you understand how things work you can use them more efficiently.

 

Anyway – she is sticking to it and it is working for her and that is great.

The thing is – the body does it anyway.  Experiments have shown that over the space of about 30 minutes, the body automatically alternates between which nostril is the predominate air intake route.  You’ve probably never noticed it unless you have been lying on your side in bed with a cold.  Eventually it gets easier to breathe.

When you do alternate nostril breathing you must spend sometime breathing through the nostril which isn’t the route of choice at that given moment.

Maybe if the body is doing it anyway there is something in it!

Paws for thought

I’ve been looking at comparative anatomy recently for an event next year but my mind went to it again this morning as I pulled on my boots to walk out into the frosty -7 degrees park.

I was wrapped up against the elements but the dogs were essentially barefoot.

Why didn’t their paws get cold?

It turns out that dogs have the same circulatory system in their feet as artic foxes and polar bears, allowing their feet to be a constant temperature down to temperatures of -30 degrees.

Usually veins travel beside arteries.  We have a similar systems in our limbs but in these animals the veins are so close to the arteries that it allows heat to transfer between the two vessels.  The heat of the arteries is used to warm up the blood in the veins so that the dogs core temperature does not drop too low.  The result is that the feet stay at a fairly constant temperature.

This is nature’s answer.

Man’s answer is to invent booties that are strapped around the dogs legs.  Strap them too tight and you may affect the blood flow that is actually keeping the dogs paws warm, defeating the purpose of putting boots on your dog. Almost the definition of ironic.

If you use booties on your dog to stop them licking off the chemicals that are spread all over the pavement then that is a different use, but be careful not to disrupt natures own heat exchanger.

Gym Confusion

I was recently asked for some advice on a gym exercise by a young rugby player.  He had been at the gym and had been shown an exercise that concentrated on working his inner biceps.

Why?  Why would anyone want to work their inner bicep? and what is it anyway?

The bicep does have two heads (bi – two, cep – head).  They are usually called long and short but arguably one is more medial (closer to the centre line) and hence you could call them inner and outer, I suppose.

We will gloss over the naming and why someone would want to do this because there is a more important point coming up.

The exercises are below.  They consist of holding a bar bell in either a narrow, normal or wide grip and then performing a bicep curl.

I have tried this and I can confirm that the wide grip version does feel like it is doing something to the inside of your arm.  But what?

The elbow joint is a hinge joint.  It is designed to hinge in such a way that your hand comes up to your shoulder.  The ulna bone of the forearm has a large hook like structure at the end of it called the olecranon.  This is the point of the elbow and it fits snuggly on the end of thelbowe humerus.  The whole structure is surrounded by many ligaments that stablise the joint.  It is not designed to have any sideways motion.

Try it yourself.  Put your forearm out at 90 degrees and move your hand away or towards your body.  What you will find is that the movement is actually happening at your shoulder joint.  If you take your arm out to the side and then flex your elbow, your hand still comes up to your shoulder – your whole arm has rotated at the shoulder joint.

If we go back to the exercises – the narrow hold one, the humerus rotates in so that when you bring your hands up they are still fairly near your shoulder joint.  The normal spaced grip brings your hands up to your shoulders.

The wide spread grip is another matter.  If you were doing this with dumb bells then it wouldn’t be a problem.  The whole arm would have rotated outwards and when you do the bicep curl the hand would still come up to the shoulder joint.  But this is a barbell!  The hands are fixed in a position wider than the shoulders.  When you do a bicep curl in this position you are forcing the joint, trying to bring the hand up to some distance to the side of the shoulder joint.

It doesn’t like it. It hurts.  You feel tension in all the structures you are trying to pull out of their normal position.  Yes you can feel it up the inside of your bicep, but you aren’t working it – you are torturing it.

If you want to do this exercise (I guess its a bicep curls that also works on your shoulder area and your rotator cuff – if that is important to you) then please do it with dumb bells.

If you have any other strange exercises that need explaining please let me know.