When you look at the structure of your spine and consider the multitudes of pressures you place on it daily, it’s easy to understand how instability could become an issue. But what exactly is spine instability, how do you know if you have it, and should you be concerned about it if you do? Let’s take a look at the anatomical structure of the spine before we address these questions.
How the Spine Is Designed
The spine consists of 24 bones called vertebrae. While these are stacked one atop the other, the spinal column is not stick-straight. There is a gentle inward curve in the cervical (neck) and lumbar (lower back) segments and a gentle outward curve in the thoracic (upper back) segment.
Between the vertebrae are the discs, which cushion the bones, absorb shock, and support movement. Behind each disc, the vertebrae above and below come together at the facet joints. These joints allow for motions such as bending forward (flexion) and backward (extension) and twisting from side to side. And all of this, from top of the spine (at the base of the brain) to the bottom (ending at the pelvis), forms a protective barrier around our spinal cord, the huge bundle of nerves that transmits signals to and from our brain and, via branches, to and from the rest of our body.
The spine is also made up of strong supporting structures, such as ligaments to control the limits of movement in the spine and the large multifidus muscle that provides stability to the vertebrae. This is where we are going to focus our discussion today, because it’s the ligaments and muscles that hold the key to spine instability.
What Is Spine Instability?
When the supportive spine ligaments or muscles are injured, this can cause too much motion in the vertebrae, or spine instability. If, for example, a ligament has become lax or torn or the muscle has weakened, the vertebrae will move too much, placing stress on the structures around it. Unstable vertebrae create excessive wear and tear on the discs as well as the facet joints and can compress the nerves.
Your doctor may order a back X-ray or an MRI to diagnose your back pain; however, while the these might show a pinched nerve or disc damage, for example, or may even look completely normal, it’s not going to show the instability. Addressing the result (e.g., bulging disc) without addressing the instability isn’t really going to solve the problem, so if you have back or neck pain, it is critical to determine if spine instability might be the culprit.
How Can I Find Out if I Have Spine Instability?
In order to diagnose spine instability, we must be able to see how the vertebrae respond while you are moving. Knowing the standard still images on X-ray and MRI aren’t going to accomplish this, how in the world do you find out if you have spine instability?
The answer lies in a flexion-extension X-ray. This is a live X-ray that takes a video image of your vertebrae as you are moving. To assess for instability in the neck, for example, the images are taken as you look down toward your toes (flexion) and then up toward the ceiling (extension). To assess for instability in your lower back, the images are taken as you bend forward (flexion) at the waist and then as you bend backward (extension). The key is to get as much flexion and extension in the movements as possible so we can get a clear visual of the spine instability if it exists.
Should I Be Concerned if I Have Spine Instability?
Yes. Stability is critical to proper function. Spine instability is a sign of worse things to come. Addressing it now will help to prevent problems later. What kinds of problems? First, spine instability can lead to instability elsewhere, such as the knee (there are some self-tests here you can perform as well). Spine instability can also stress the facet joint and lead to arthritis or put pressure on the nerves, irritating not just the back or neck but also other structures the affected nerve branch supplies (e.g., the hip, knee, or ankle if it’s a lower back nerve). Discs can become overly stressed, causing bulging, herniations, or degeneration.
A simple flexion-extension X-ray will allow your interventional orthopedic physician to assess you for spine instability. If there is spine instability and/or other spine issues, such as those discussed above, there are nonsurgical treatment options that may be able to help. However, making sure you have the right test to assess the source of your back pain is key!