• Slipped discs as you would imagine from the name, don’t actually exist! This is a popular term for a common injury that has lead to a lot of misperceptions about back pain and sciatica – so let’s clear it up and explain what is really going on.

    spine anatomy and slipped discsLet’s start with the basics: Quick anatomy

    Your spine is made up of bony vertebrae stacked on top of each other with a shock absorbing and flexible disc and vertebral end plate in-between each of them. Your spinal cord runs down a tunnel behind the main body and or the vertebrae and the disc as shown.

    At every level, a spinal nerve branches out of the spinal cord innervating your entire body. Having these nerves in such close proximity to your vertebrae and discs is why back pain now be so painful in the very acute/early stages and this makes the area very sensitive.

    The interesting thing about the vertebral end plate is that there is both a bony and cartilaginous endplate that create an exceptionally strong connection to the annulus of the disc making it IMPOSSIBLE for the disc to SLIP. Yes, you heard that right. DISCS CANNOT JUST SLIP OUT OF PLACE willy-nilly like a bar of soap in the shower. The endplates function to hold discs in place, evenly spread applied loads, and to provide anchorage for the collagen fibers of the disc. They also act as a semi-permeable interface for the exchange of water and solutes which can be seen in the following illustration.(4)


    slipped disc herniated disc physio ashburtonSo now let’s move on to the mechanism of injury, how does a “slipped disc” happen?

    The technical term for this injury is actually disc herniation or protrusion disc, which describes the injury much more accurately.

    Many people freak out when they imagine that a disc in their back has somehow slipped out of place, but really they can’t go out of place – this is a really common misperception.

    In reality, the injury is caused not by one accident generally but a build up over time. Here are the three main causes of disc protrusion:

    1. Repeated microtrauma – A gradual build-up

    This is the most common method by far. The disc can be injured through repeated or sustained twisting, flexion (bending forward) or compression. Here is an example of this:

    • Poor posture. If you have poor posture when sitting at a desk at standing then your spine is receiving extra stress. Sustained rounding out of your spine places a lot more pressure through the front of your disc, increasing the pressure on the back of the disc as the gooey substance in the nucleus gets pushed backwards. Over time this can lead to herniation to the disc and injury.

    2. Sudden trauma

    This is when your spine gets a huge amount of load through it, causing a tear int he outer part of the disc, leadign to a protrusion. This can occur from things like car crashes.

    3. Genetic

    Genetics comes into play with a lot of injuries, leaving you at greater risk of injury by way of 1 or 2 above. Genetics is very hard to change though so it is best to try to minimise the risk of the above two causes.


    What are the signs or symptoms of a disc injury?

    • Pain when:
      • Bending forward
      • Sitting
      • Coughing or sneezing
      • Lifting
      • Getting up first thing in the morning
    • Pain referring down your leg (sciatica)
    • Pins and needles
    • Weakness in your legs

    So how do we help disc protrusions?

    The good news is that 90% of cases have a good outcome with conservative treatment – so if you have any of the above symptoms, or in fact any back pain – book in to see a physio because it does help and the majority of people are pain free within 6 weeks.(3)

    Your physio can help you with:

    • Relieving muscles in spasm
    • Decreasing inflammation
    • Showing you the correct strengthening and stretching exercises to address it at home
    • And most importantly teach you the right technique to lift and how to work with a better posture.