Why Do Disc Herniations Occur?

Ask anyone who has gone through the recovery from a major spinal disc injury and they will tell you that they would have done everything in their power to prevent it, if only they could go back in time. A strong, healthy back allows you to play with your kids, play golf, go for a walk, and do all the other things that make life worth living. A severe disc injury, like some disc herniations, can take you away from the important things in life but can also take you away from your livelihood as well. The first step in preventing these disc herniations from happening is by learning about them. Hopefully, this article can help you with this first step.

To understand how intervertebral disc herniations occur, we must first discuss some anatomy. The spinal vertebrae are separated by cartilaginous discs that act as spacers between the vertebral bodies and function as shock absorbers.

What are intervertebral discs?

I often compare the intervertebral disc to a jelly donut.  The center of the disc is the jelly. The jelly center is contained by thick concentric fibrous rings of connective tissue. In a healthy disc, the jelly sac is full of fluid and the fibrous rings are hydrated and strong enough to contain the jelly within the center of the disc.  The fluid content of discs make them highly effective shock absorbers.

What are the causes of disc degeneration?

Intervertebral discs have very little blood flow. Instead, discs use a process called ‘imbibition’. Like a sponge, when a disc is compressed the water is squeezed out. When the compression is removed, the water is drawn in and fills it up again.  This process keeps the discs healthy and hydrated.  If the discs do not go through this activity frequently with normal spinal function, they dry out.  If a lack of proper spinal motion continues, the once strong, fibrous rings begin to crack. Like a tree that has been cut down, eventually the wood becomes brittle and much easier to break as the moisture content is decreased.

What causes a disc herniation?

Intervertebral discs can undergo a variety of biomechanical forces. They can be stretched, twisted, sheared, or compressed.  While these are normal forces for discs, they tend to be more susceptible to injury during twisting and compression. Repetitive stress to a disc will eventually displace the jelly towards an outside edge. If there is any cracking, this powerful hydraulic pressure will eventually cause the jelly to migrate and exert pressure on the outside fibrous rings. Initially, this pressure can result in a bulging disc.  Eventually, this pressure can push through the outer rings and lead to what is called a disc herniation or disc protrusion. If the jelly is forced out and separated from the disc, it is often described medically as a progression from a ‘disc extrusion to a disc sequestration’. It is possible to create enough force to herniate a disc with a single compressive load; however, it is more likely that is occurs suddenly following years of this powerful hydraulic pressure exerted on a disc that has dried out due to the effects of degenerative changes.

If you are spending hours sitting at a computer desk with a slouched posture (checkout our blog post about Office Ergonomics) or doing repetitive tasks in awkward postures (check out this post about sitting, standing and lifting postures), you are exerting more stress on the discs and less likely to allow for proper hydration during normal spinal movements. Typically, I find that disc injuries happen when you least expect it. The body’s ability to guard and stabilize the spine is normally very effective at preventing injury. If you are thinking about a certain movement or lift, it is possible to contract your core stabilizer muscles to guard against excessive shearing or rotational stresses that may cause injury. When you are not consciously thinking about the movement, you are depending solely on your intrinsic core stability system that braces and prevents excessive motion on it’s own. Unfortunately, the old adage is true: “If you don’t use it, you lose it”.

Following injury, sedentary lifestyle, or chronic poor posture, we find our bodies lose their capacity to stabilize when they need it the most. If I were to pick the most likely scenario in which a disc injury can occur, it is not from moving heavy furniture awkwardly, although it is possible.  It happens more often, after you are lifting heavy furniture awkwardly all day long or when you are slouching at a computer all day; And then, while exhausted, and not thinking about about the simple motion, you attempt to pick up a penny. This, or a similar scenario, is how you are going to throw your back out and end up with a disc injury. Please don’t let it get to that point.I will follow up with articles about how to work towards improving spinal health, including core strength and stability. Please don’t hesitate to ask myself or your health care provider if you have any questions about preventing these injuries.

Please comment below and let me know what you think!




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