The Secret Life of Bones: Reflections on training, injury and the equine skeleton as dynamic, living tissue

Nov 25, 2013

 

Look at the picture of the skeleton below. Just some old, dead, bones… right?

 

When we think of bones and skeletons, we often consider them in the context of death.

A while back, I shared the following photo of the 6th lumbar vertebra and sacrum of a horse with some quite serious pathologies. My friend, Caroline Larrouilh, made a comment which truly resonated:

 

“I think we forget that bone is alive.”

 

 

 

Take that statement, and I’ll let you think on it for a second.

Then, I want you to consider this quote from another equine professional I admire, Professor Robert Bowker. He has a saying that comes up in many of his lectures (multiple times in some of them!), that “conformation is a moment in time.”

When we think of a skeleton, we don’t just associate it with death; we also tend to think of it as static, even in the living horse. And, as Caroline commented when she read the first draft of this article, we also don’t think of bone as tissue.

In my massage training, and in discussions about massage and muscles all around the world, we often use a saying, that “bones don’t move muscles; muscles move bones.” It is one of my favourite sayings. But it talks about muscles being responsible for movement, and bones providing the anchors for those muscles to work on; we’re considering those bones as levers – levers for the muscles; something static and strong and hard.

We don’t think of them as something that constantly changes and adapts.

Another important topic that has garnered more attention in recent years, is the concept of just how long it takes a horse to mature, and the fact that we ride them well before their growth plates have closed.

But does that mean the skeleton has stopped changing when the horse is mature? When that last vertebral growth plate has closed? Does that mean it no longer adapts and transforms?

No, it doesn’t.

 

We often use a saying, that “bones don’t move muscles; muscles move bones.”

It is one of my favourite sayings. But it talks about muscles being responsible for movement, and bones providing the anchors for those muscles to work on; we’re considering those bones as levers – levers for the muscles; something static and strong and hard.

We don’t think of them as something that constantly changes and adapts.

 

It isn’t as simple as bone just being a collection of minerals, or something hard to anchor muscles on. All riders and trainers need to understand how bone works, what it is made up of, and how those cells behave.

The worker-bee bone cells are called osteoclasts and osteoblasts. In the most basic terms, osteoclasts are the ‘bone-breakers’, associated with resorption, while osteoblasts are the ‘bone-makers’ – and the main subject under the microscope in this discussion.

In healthy bones, these cells function together to elicit a natural, normal turnover of bone tissue.

But what happens if we create unnecessary stress, or something throws that fine balance of turnover out of kilter? What happens if there is abnormal tension on a particular part of a bone, or if there is undue wear and tear, or inflammation? What happens if there is instability?

Just as bone can degenerate, it can also throw down more bone via our osteoblasts, as a way of trying to support the body when something goes wrong. When everything falls apart, if the soft tissue isn’t functioning properly, bone will create extra bone to try and make up for it.

Sometimes, this is when we can start to see things like bone spurs. How we will refer to these depends on where we find them. ‘Bone spur’ is a pretty general term, and the one many of you are probably familiar with. But let’s break it up a little further so you can understand how they work.

We have two types to consider in this discussion. One is the osteophyte, found on joint margins or in joint spaces as a bony projection. In contrast, the enthesophyte is found where soft tissue such as a ligament or a muscle’s tendinous attachment inserts upon bone.

What we need to realise is that such bony growths are a response to stress, and when either of these are created, there has already been significant damage done. Wear and tear is one thing; but it is not normal to have excessive bony proliferation.

We could get into where you could find these in the legs, and in particular, the feet, but what I really want to talk about is the horse’s spine.

The equine and human spines differ somewhat, with the horse’s intervertebral discs being of a more fibrous nature, relatively thin, and less elastic. As bipeds, the human spine is designed to absorb shock and torsion in a way that the spine of a quadruped such as the horse cannot. However, the spines of both species also possess pairs of synovial intervertebral articulations, commonly known as facet joints.

I’ve heard it said time and time again, that in humans, facet joint arthritis is “normal” in a large percentage of the population, particularly in the lumbar area, and simply part of the aging process.

As someone who, at 19 years of age, had an MRI reveal changes to my own lumbar facet joints, I beg to differ. When the orthopaedic surgeon viewed my MRI results, he said that at 19, I had the spine of a 45 year old.

How did that come about in my own body? Well, the MRI was taken because of an injury that occurred six months earlier, and the general consensus was that those changes could not have occurred in the space of six months; that they would already have been underway earlier in my teens.

I’d had mild back pain before, but nothing like this injury. But, what was occurring in my body, according to these orthopaedic specialists, was that not only was I very tall, with a long torso and long, fairly weak back, I also had hypermobile joints.

So, yes – these changes had been under way for a while from some slightly abnormal stresses.

These changes in my back didn’t really bother me, until I upset the apple cart. While a simple injury, once it happened, I could suddenly feel exactly where those changes were, because there was inflammation.

Getting back to the horses, I’ve read in many scientific journals and equine textbooks that, like humans, changes in the equine spine are a normal sign of aging.

I don’t know which horses they were studying, how they found them, their age, or what their histories were. However, I do wonder WHY those horses were on the dissection table, for them to be able to find these changes in such numbers as to be able to call it “normal”.

Why?

These are things that often can’t be seen without opening up the horse. You can image some lesions in the horse’s spine, but it’s very difficult to identify many problems radiographically. Imaging is not yet at a stage where it can visualise everything in the horse; often, there is simply too much in the way to be able to gain clear pictures.

Of course, it is normal to have degeneration to some extent; to have some changes. We are all going to accumulate wear and tear as we age. That’s life.

But what I find very concerning, are the severe changes in the bones of horses that are the result of asymmetry.

I do not believe that such severe changes, and asymmetrical changes, can be accepted as normal. I think we need to reflect on why.

The horse in the photo that Caroline commented on was the subject of a dissection conducted by Sharon May-Davis. A warmblood in his early 20s, he had been retired from dressage sometime in his late teens, to my knowledge. We found many things on dissection that pointed to some traumas, some things that the horse had been carrying since a very young age, but also some things that were the result of longstanding asymmetry and dysfunction.

His skeleton was to become the first in my growing collection, and after the dissection concluded, I cleaned his bones by hand; a task undertaken with appreciation and respect, with the thought that he could teach people for many years to come through the stories held in his skeleton.

This horse was found to have severe temporomandibular disorder, being that at the temporamandibular joints (TMJ), where the skull meets the jaw, there was significant damage, with restricted motion to the right, and virtually no movement whatsoever on the left.

During the dissection, we discovered countless other changes to various joints and soft tissue structures, and we did also find changes to some bones.

But until I actually cleaned the skeleton, we weren’t able to see the extent of the damage to his bones. We weren’t able to see the extent of the asymmetry, and the changes it had caused.

When I rinsed off the bones of the vertebral column, and laid them out in order, I did not find a single pair of symmetrical facet joints.

Some were milder than others, but the changes in other pairs were severe. Some were razor sharp.

And as we see in the photos of that last lumbar vertebra, the dorsal process of that bone had begun to skew and curl over. It reminded me of the orca from Free Willy, and the way his dorsal fin curled over after time in captivity.

 

 

To see such an important bone so skewed, and so damaged… It was a bit of a shock to the system.

This wasn’t the only change to his lumbar vertebrae. He also had a bony hook, more correctly termed ventral spondylosis, on the underside of one lumbar vertebra. This was located in front of two lumbar vertebrae where the transverse processes, the big wings that extend to each side, had fused together.

Several of these transverse processes had overlapped and fused, but mildly enough that after cleaning, the bones separated in those areas. This one, however, was properly fused. There was no way those two bones were going to come apart with any amount of cleaning. There was so much extra bone there that it looked like someone had taken to the area with a tube of Selleys All-Fix. There was no way of separating that.

One of the first areas of concern, I found by accident, when we were initially taking things apart in preparation for cleaning. When I disarticulated the cervicothoracic joint, where C7 meets T1 at the base of the neck, the osteophytes on the facet joints were so sharp that I sliced my glove open and cut my finger.

 

 

I had the privilege of assessing this horse prior to euthanasia, and among other things I observed, he had little flexibility when it came to turning his head, and when he did have any bend through his neck, you could hear audible popping and crunching of the joints of the lower cervical spine.

So, did those joints become restricted because of something else? Because of inflammation and injury itself? Or did they become restricted because he stopped moving them properly, since it was uncomfortable to do so?

 

 

According to what we are so often told, that is just normal wear and tear, and part of the aging process. Based on the correlations I could make from life to death with this horse, let alone the horses I have my hands on from day to day, I’m inclined to disagree.

I could continue describing the changes I found on this horse’s skeleton, but I think I’ve made my point, and I think it is very simple. As Caroline summed it up, “I think we forget that bone is alive.”

 

 

For those asymmetrical changes in the spine to occur, there were asymmetrical changes in the soft tissue first. The horse was crooked.

For these changes to have occurred the entire way through the spine? I guess we’ll never know what exactly came first; whether it was changes to his hind end, of which there were many, or whether it was changes that started in the structures of the head, because the horse had sustained an injury at a younger age that may have created the perfect storm for those changes to begin. Perhaps it was some other form of crookedness that started in the front end, the hyoid, the TMJ, from the poll, the feet… Who knows which end it started from, and how much was exacerbated by other factors like training?

What we do know, is that a problem in either end will affect the entire body.

This is undeniable. The horse’s body is structured in such a way, that dysfunction in one area, will snowball through the muscular system and all its fascial connections, until it affects many areas.

This happens in humans too, but I think it is perhaps more important in horses, who, along with being inappropriately designed for carrying heavy loads on their backs, are so inherently connected from the back end to the front end. And this is something that dressage people have drilled into them constantly; that they have to have the horse driving from the back end, connected and “over the back.”

The other thing I need to point out is that this connection isn’t just the muscles, isn’t just the thoracolumbar fascia, but is all the fascia. We underestimate the importance of the myofascial system.

Fascia is like a web of fibrous, collagenous sacs, encasing all of the muscles, and interconnected throughout the entire body. It really should be considered as almost an organ or system in its own right. It is part of the musculoskeletal system, sure, but it is also so integral to healthy locomotion and neurological health, that it really needs to be considered according to the importance of its healthy function.

 

 

Any damage to any fascia, anywhere, is going to cause damage somewhere else. It is torsion, tension and dehydration in fascia that restrict some muscles and result in overuse of other muscles to compensate.

The notion that compensation for one tiny little niggle in one area, can lead to asymmetry and crookedness throughout begins to make more sense when we view the horse’s body through this holistic lens.

 

 

 

Any number of things can set up a pattern of crookedness in the horse. Natural laterality; uneven feet, whether from grazing in a particular stance, or from injury; a small soft tissue injury that has gone unnoticed and untreated because it’s something you can barely put your finger on; a crooked rider (that is one we don’t like to admit!); a crooked saddle…or a straight saddle on a crooked horse that can exacerbate it further; riding the horse stiff, crooked and tense (perhaps one of the biggest culprits); or any combination of the above.

Bringing these thoughts back to our main point, that bone is living tissue; that it breaks down and builds up, turns over, regenerates, and responds to stress…

Does it make sense now, that if you have crookedness, if you have asymmetry, or if you have dysfunction and compensation, that it is only natural for the bone to respond; to try and stabilise and protect, by producing more bone tissue? By growing osteophytes and enthesophytes?

Because that is just the thing. We cannot treat bone as though it is dead. We cannot treat bone as something that remains static and unchanging once the horse matures.

We have to consider it as living tissue; that it is as alive as muscles, or the heart, or the mind. Because bone IS alive.

And when we mess up something else, bone will do its best to compensate. Bone is affected by crookedness as well as concussion, and the manner in which bone is laid down is affected by movement, whether correct or not.

The result? Pictures like that lumbosacral joint, where one facet joint looked a bit odd, and the other was just diabolical, pointing in a completely different direction, with three or four times as much bone in that area, trying to make up for what else wasn’t working.

Soft tissue, much of the time, we can heal; treat; improve; fix the dysfunction. But when you fail to treat soft tissue, or when you fail to correct your horse’s crookedness by training them to move freely with suppleness and straightness, you are setting the horse up to have bony changes. As Dr Kerry Ridgway says, muscle issues occur first, then tendon and ligament problems, and finally, skeletal changes.

And those, you can’t simply massage away. You can’t just manipulate them and restore the movement. While the bone is alive, it does not mean that we can change it once past the point of no return.

Those bony changes become a problem in and of themselves, instead of a response to a smaller problem that could have been fixed.

So, let us look at that first picture of the skeleton again.

Sure, they might be old, dead, bones. But there is more to this image than meets the eye.

 

 

“Ginger” was put together by Sharon May-Davis, Libby Franz, Anita Evers, Lynette Eggleston, and a number of previous dissection students as an evening project during a workshop at Andrew and Nicky Bowe’s rehabilitation centre in Victoria. Ginger had been the subject of another dissection previously, and with a bit of history, along with the findings of that dissection workshop, they were able to consider what they could see on Ginger’s skeleton in the context of how it had occurred, instead of just as dead old bones, or merely something average and normal.

But that’s not all. Ginger was put together in such a way that her legs can be moved. And this is where she really comes to life once more, as a teacher even in death.

With a student on each leg, Ginger can be made to go through all sorts of different movements. Students can discover how the bones are meant to move, create incorrect movements, and see and feel just what is right and wrong, and what incorrect movement can do underneath the skin; something we can only imagine when we’re looking at a live horse.

But perhaps one of the most valuable things about Ginger, and something I really treasure as a lesson from Sharon in itself, is that she has a name.

Before a dissection workshop with Sharon can begin, the class needs to acknowledge the horse’s identity; that, even though it is now on the table, the horse still has a name and a history.

And if that horse is anonymous, the horse is given a name by the students, so that they can value the horse and think of it, not just as a carcass on the table, but as a creature. A creature who could move, and feel.

And, as we often find on the table, a creature who could feel pain.

 

This doesn’t relate directly to our concept of bone as something that is alive. But I think it is incredibly important.

Because even when we look at dead old bones, if we look at them as being something that came out of a living horse, and think about how those bones moved, or weren’t able to move in life, and how they came to be that way, how those changes actually occurred…

We can understand that bone is living tissue, as much as any other kind of tissue we find inside the body; that, as Sharon often says, bone never lies.

We realise that when we ride our horses, and feel that something is not quite right, we need to stop at nothing to find out why. To not just manage the symptoms, but to try and get down to the root cause, and treat the primary problem.

The fact is that bone is alive, and if we don’t fix a problem, bone will try to, whether it does it in a beneficial way or not.

This is knowledge to take to the saddle, and every other aspect of horse care and management.

Muscles don’t just move bones in the sense of locomotion. Through their role in posture, crookedness and concussion, muscles can change bones.

When we are talking about different forms of bodywork – chiropractic treatment, or massage, or myofascial release – we need to consider the musculoskeletal system as a whole; as a collection of living tissues that work together.

So, to conclude, let’s go back and build on that saying.

 

Bones don’t move muscles; muscles move bones.

And if things are not moving properly, muscles will change bones.

 

 

© Cat Walker 2013