Updated: Oct 1, 2019
"Inter vertebral disc"- the elusive mystical creature that lives in your back. Many believe that it is capable of bringing pain in the back and leg when its wrath is upon you. Without any wrongdoing this poor disc has gained a lot of bad reputation in our society.
People believe that this disc is very fragile, the myth being- it can get injured very easily and can move out of the spine like a soap bar slips out of hand while bathing. These days everyone seems to be talking about this disc, people know very little but have a lot to say about it.
So what is right about the disc? Is it fragile? How does it get injured? How does it heal?
Let's get to know:
When you see the anatomy of a disc you will understand what role it plays. Below diagram shows the disc between your vertebrae:
Our spine consists of 32 vertebrae which are divided into five regions, those are: cervical (neck), lumbar (low back), thoracic (mid back), sacral and coccyx (tail bone). The sacral, coccyx and first two cervical vertebrae do not have any disc between them. However, the disc is present between the other vertebrae, these discs form a joint between two vertebrae and allow movement.
Discs are composed of outer fibrous ring referred as Annulus fibrosus. It consists of several ring like structures and made up of fibrocartilage. This annulus surrounds an inner gel like substance called nucleus pulposus.
Nucleus helps in absorption/ distribution of forces coming on to the spine, it prevents these excessive forces to reach the ligament, bone or end plate which can cause further damage.
Annulus and vertebral end plate form a very strong connection which makes it impossible to slip. I repeat again THIS DISC CANNOT SLIP.
How strong is our disc?
The shape and structure of the disc mechanically makes it easier to dissipate load and provide mobility at the same time. According to researches our disc can bear compressive load of more than 350 Kgs. This study was done on a cadaver but with dynamic nature of human body it can easily bear more load.
Your back pain is because of disc?
I can't even count the number of patients who have told me that now they can't do bending, walking, running, exercising or live a life because they have "slipped disc". According to a 2015 study by researchers in Japan, done on more than 1200 people of different age groups and gender who didn't had any pain during the study. More than 90% people presented with disc bulge on MRI in young age and 70% people who were more than 50 years had disc herniation and they didn't complain of any pain.
This study clearly suggests that MRI findings of disc bulge, back and leg pain doesn't have any co-relation.
What if disc is injured?
As any other tissue in our body, a disc can also get injured and heal. Disc is usually injured when there is shear forces working on it, same as any ligament injury in knee or ankle.
When the disc is injured, our body follows a simple rule for healing- larger the disc bulge body deems it more threatening.
Sequestration (very very large disc bulge) disc can regress upto 96% and in 43% of individuals it can resolve completely.
Extrusion (very large disc bulge) 70% regression and 15% complete resolution.
Protrusion 41% disc regressed on its own.
Mild disc Bulge 13% regression.
In conclusion, this is now understood that the disc can get injured and it can also heal itself. Self resorption can take some time, and nobody can wait or suffer for that long. That is when creating a right environment for healing comes into play with help of Physiotherapy, medication and other therapies to make the person pain free till the body can heal itself.
Author is Principal Physiotherapist & Co-founder of Synchrony orthopedic & sports physiotherapy clinic.