What are intervertebral discs and why do they "slip"?
We've all heard it, "I've slipped a disc in my back, i'm in agony! I was only picking a sock up off the floor!"
This blog will attempt to clear up a few common misconceptions about your discs or Intervertebral Discs are they're referred to medically.
First, we will hold a little anatomy class, this will help you understand just whats going in your back when you injure a disc.
Intervertebral discs are roughly the same shape as a kidney bean. The inner part or the core of the disc is made up of a soft almost gelatinous tissue called the Nucleus Pulposus. The Nucleus Pulposus is surrounded by and held in place via a very strong, fibrous structure called the Annulus Fibrosus.
So if the Discs aren't "slipping" what are they doing?
Well, now that we have an idea of the anatomy of an intervertebral disc we can talk about how they get injured and why they can hurt so much!
The most common reason an IVD will cause you pain is because of a protrusion. This is where the softer nucleus pulposus pushes against the annulus and forces it to bulge outwards, the nucleus doesn't burst through the fibrous ring in this case but rather just pushes it outwards. Sometimes as a result of this bulging, the nerve roots that lay very close to the discs can become compressed or pinched, sending pain down the leg/s. So, the whole structure has not slipped out from in-between the vertebra its just changed shape slightly.
How do I know if I have a disc injury?
Well fortunately they are quite rare, making up just between 1-3% of all lower back pain cases.
Usually patients are between the ages 25-45 this is because the nucleus pulpous is at its most hydrated within this age range.
There is a male prevalence with a ratio Male 3:2 Female.
Usually a sudden onset of lower back pain & potential leg pain which goes past the knee.
Pain may follow heavy lifting but can be from a fairly innocuous activity.
The pain is most commonly described as shooting or electrical type pain.
So why did my disc protrude when I picked a sock up off the floor, they aren't heavy?
In this case, the disc protrusion is a result of repetitive micro trauma. For example, if you have bent over to pick something up incorrectly 10,000 times in your life, then that nucleus pulposus has been forced to push against your annulus fibrosus 10,000 times. Each time you did it, the annulus got marginally weaker but over time this micro trauma makes the disc weaker and weaker and eventually we have a case of the sock that broke the camels back..or your back.
Microtrauma has a wide and varied array of mechanisms. Most commonly it is caused by poor seated posture particularly for those who work long hours at office jobs. Poor sitting posture, i.e. slumped forward, shoulders rounded head held forward puts an enormous strain on your discs and they tend cope very well with this, until one day they don't.
Lets do some maths, we shall use a 70kg person as an example. When that person is standing with good posture the disc load (pressure) is at 100%. When that person is sitting with good posture, the disc load increases to 140% of body weight or 98kg of pressure. Sitting with bad posture takes this up to 185% or 129.5kg of pressure within the disc. So, this makes it a bit clearer as to why sitting with incorrect posture over a prolonged period of time can cause disc damage.
What are the main symptoms of a disc herniation?
The symptoms vary depending on the severity of the herniation but the most common signs and symptoms are:
Electrical type shooting pain that may radiate down the leg to the foot.
Muscle weakness in the lower limb
Numbness in the lower limb
Tingling in the lower limb
Lower back pain
Foot drop i.e. struggling to lift your foot upwards to your head.
Will I need surgery if I damage a disc?
Fortunately, most disc herniations do not require surgery. However, if this disc is severely degenerated as well as herniated, it can cause a severe disruption to your every day life and in this case surgery might be necessary.
If you are in the majority that does not need surgery, less invasive treatment will be used to help you make a full recovery. Chiropractors use techniques such as:
ice/ heat therapy
specific stretches and exercises,
flexion distraction technique
How will the Chiropractor diagnose a disc herniation?
Any diagnosis starts with a thorough case history. The chiropractor will want to know as much as they can about your pain such as when it started, how long it has been going on for, what are your main symptoms? etc, etc.
The chiropractor will then perform a physical examination starting with a neurological exam to try and identify if you have a disc herniation, how severe it is and what level of the spine the disc is located.
You may also need some imaging such as an MRI scan which can show the spinal cord and the discs in great detail.
How do I prevent a disc herniation?
Use proper bending and lifting technique, do not bend at the lower back. Instead, bend your knees and hinge at your hips keeping the lower back straight.
Maintain a strong core, a fantastic exercise to strengthen your core is the plank.
Maintain proper sitting and standing posture.
Maintain a healthy weight and don't smoke.
Thanks for reading.