Let's start by explaining what we mean by chronic low back pain. The official definition of chronic or persistent pain is when something hurts for more than 6-12 weeks. The term 'acute pain' is used to describe pain that has been around for less than 6-12 weeks.
When medical professionals talk about the word 'chronic' they are not describing how severe or bad the symptoms are. They are talking about a type of pain, not how it feels. If you have heard someone say 'my lower back is really chronic today' meaning that they are having a bad day with their symptoms; this is not the same as the medical term.
This time frame is chosen as that is the normal healing time for most tissues – most things get better in 6-12 weeks, even broken bones. So if you still have pain after 12 weeks then something other than tissue damage has probably got something to do with it.
This is just a rule of thumb and personally I find these 6-12 weeks a bit confusing and not always very helpful as the time frame differs for everyone. You can start to have chronic pain much earlier than 6-12 weeks and sometimes acute pain lasts longer than this and does eventually go away.
The video below explains the reason for the 6-12 week timescale.
So although this 6-12 week timeframe is a useful guideline I prefer to think about it in a much more simple way:
Pain is a brilliant survival system. We need to know if we are injured so that we can:
You only have to look at people with diseases that affect feeling to see how easy it is for them to overlook injuries that then become infected or worse. Take a diabetic with peripheral neuropathy and loss of feeling in the feet who may not have noticed a foot ulcer developing. The consequences of this can be terrible and can result in the loss of the limb.
If you are experiencing pain it is natural to try and get to safety, it lets you know you need to move or get away from the threat to you. For example I have been swimming in the sea and been stung by jellyfish, my overwhelming instinct was to get out of the water first and foremost – 'get me out of here' my brain was yelling at me, this environment is dangerous to me. And that was helpful pain; it made sure I took myself away from danger and didn’t get stung again.
Most of us try not to repeat painful mistakes. Watch a toddler putting their fingers into everything and the shock and surprise on their face when they experience pain. We learn to keep ourselves safe by evaluating these experiences and deciding if they pose a threat to us and hurt is an important teacher. Not many of us touch a hot stove more than once unless it is accidental.
Note – all these three things - taking care, running away, learning from experience - are all things that are processed by our minds. It is our brains that decide how we behave toward this painful experience. This is a very important point that I will come back to.
With chronic pain there is no longer anything to protect - any soft tissues injuries will have healed, longstanding changes to joints such as degenerative changes generally don’t need protection from movement – the opposite in fact.
This is not keeping us safe from danger and it does not even teach us useful experiences about what to avoid in the future because the pain is often unrelated to an injury. For example some people feel worse just thinking about certain movements –this is not helpful.
Chronic lower back pain does not help you do well – it has the opposite effect.
This collection of ill effects is called chronic pain syndrome.