Why does my back hurt?

Did you know that around 85% of all cases of back pain have no known cause?

Contortionist_Ravi_standing

Specialists call these “non-specific” or “mechanical”. “Mechanical” because pain is typically aggravated or relieved by a particular movement or position, such as bending forward or standing still. Non-specific back pain can range from mild aching and stiffness to severe and disabling pain.

At one time, specialists believed that back pain was due to injury or “wear and tear”, visible on X-rays or scans. Now we know that signs of disc injury or wear and tear are very common and have only a very weak relationship to pain.

The mysterious nature of idiopathic back pain is a real problem. Sufferers often go to their GP, who often feels under pressure to provide some sort of explanation. Unfortunately this is sometimes “it’s your age” or “wear and tear” when in fact it’s neither of those. Often people with back pain are referred for an X-ray or MRI scan if it’s not getting better. If the report comes back saying the back is normal, you could be left with the impression that either your back has some sinister undiagnosed disease, or you are complaining for no good reason. If you get to read the report, you might be lead to believe that normal wear and tear indicates your back is damaged and weakened. Not a happy situation.

Most cases of back pain can’t be diagnosed by MRI, X-rays or even blood tests. However, these can be useful to rule out more specific conditions. So what does cause back pain in most cases? How can you get a painful and disabling condition without disease or injury?

Well, there is a third alternative to disease and injury: dysfunction. That is, the tissues are basically healthy but the organism is in some way uncoordinated, and that puts strain on tissue, leading to symptoms: pain and stiffness.

But how can the back become “uncoordinated”, and how does that lead to pain and stiffness? The thought that the back (or the body in general) could let you down like that is rather unsettling! You have to remember that the body, like everything else in the physical world, must obey the laws of mechanics. When designing a mechanical device, an engineer is faced with certain trade-offs and needs to find the right balance. In the case of the human body and the spine, evolution/God (take your pick) has also had to ‘decide’ between stability and adaptability.

redundant chain

‘Redundant’ chain-like structures such as the spine have many ways of to carry out the same task.

This leads us to how “redundancy” is used in the design of mechanisms. Redundancy means having more than one way to do the same thing. Consider the design of spacecraft. Unlike cars, they have many layers of redundancy built in because you can’t just call out the AA if it breaks down. So, for example, the NASA Curiosity rover has six wheels instead of four, each with its own engine.

Similarly, the human spine has a ridiculous number of joints in it – 74, not including the joints between the spine and the ribs. No-one ever needs that many joints, not even for the most extreme contortionist’s party trick! Think how many joints you actually need for bending forward – you only really need one hinge joint. No engineer in their right mind would design a crane, for example, with 20 hinge joints. It would be grossly unstable unless you had a very sophisticated control mechanism, sharing out the load just right.

On the other hand, the problem of building a crane with just one hinge joint is that if that joint seizes up the crane will not work at all. But if you have two, you can use the control mechanism to change the motion pattern, which will allow the crane to carry on working. Here lies the benefit of having a spine with so many joints. There are many people walking around with worn-out intervertebral discs who have no back pain or stiffness. Their spines have adapted happily to this change.

Unfortunately, the spine doesn’t always adapt in such a way that it can carry on regardless. The fact that it can move in an infinite number of ways also means that it has the freedom to move in ways that put excessive load on certain parts of the system. It can also fail to coordinate properly so that the muscles are working against each other, leading to painful spasm. Muscle is often the immediate source of the pain in these cases because it has the ability to cut off its own blood supply. When a muscle contracts, the pressure inside the muscle rises and it doesn’t take much for that increased pressure to counteract the weak pressure pushing the blood through the muscle. If a muscle stays contracted for too long, the lack of oxygen will lead to pain and stiffness.

These cases of back pain are like an engine out of tune. If you were to take an engine that is out of tune and X-ray it, or even take it to pieces, you wouldn’t find anything wrong with it. But if you were to run it, you would hear that the engine was not coordinating properly, causing strain and back-firing.

Osteopaths aim to restore normal function to sort out the back problem. We make extensive use of palpation (locating and assessing painful areas by touch) and observation to detect things like muscle tightness, shortening, uneven distribution of spinal joint motion, imbalance of muscle activity and so on. Through advice on movement and posture, exercises, manual treatment of tight tissues and joints we aim to get the engine back in tune.

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