I regularly see patients who’ve been told that they have “arthritis, bulging discs, herniated discs, bone on bone, ruptured discs or degenerated discs”. They are terrified that they will become increasingly disabled and need to be especially protective of their spines. Their lifestyle may become quite limited. We know that if you view any body part as “damaged”, you’ll tend to focus on it and the sensations from that area become magnified. Then the next logical step in thinking your spine is “a disaster” is to be worried about becoming paralyzed. None of this is true. We don’t know the exact source of back pain most of the time. But we actually do know that the discs between the vertebrae are not the source of chronic pain.
Discs lose water content and become stiffer as we age. Since MRI scans are dependent on the signals created by water, less hydration means less signal and a darker disc on scan. That’s it. That is all it means. It doesn’t mean it’s a source of pain. A more accurate term for this condition would be “normally aging discs” instead of “degenerative disc disease.” It’s not a disease. It takes me some time to explain to them that none of these conditions are a source of back pain.
A less flexible spine doesn’t usually correlate with a painful spine. There have been multiple studies done in the cervical, thoracic, and lumbar spine demonstrating that there is little correlation between a degenerated, herniated, bulging, or ruptured disc and back pain. (1) For example, if you randomly study 100 people who have NEVER experienced significant low back pain, by age 50, the majority of them have bone spurs, herniated or ruptured discs, disc bulges, or “degenerative disc disease”. By age 65, it approaches 100%.
There was a study done in the 1950’s that showed that after a disc operation, the chance of having low back pain after surgery was less if there was more degeneration of the disc and therefore less motion.
I encounter this scenario daily in clinic. Patients come to me with severe leg pain from a pinched nerve and no back pain. Yet the x-rays and MRI scan often show that the spine has severe arthritis, degeneration or ruptured discs. I have undergone two low back surgeries and my three lower discs are severely degenerated on MRI. Nonetheless, it is my right arthritic knee that slows me down, not low back pain.
Severe degeneration and no LBP
I evaluated an active middle-aged woman with extreme pain down the side of her left leg every time she stood up or walked. She had no pain with sitting or lying down. She was an avid cyclist, runner, and worked out at the gym regularly. She had narrowing around her fifth lumbar nerve root as it exited out of the side of her spine. Every time she stood up, the fifth nerve was tightly pinched. Her spine was one of the worst looking spines I have ever seen in any person of any age. Every disc was completely collapsed and each vertebrae was bone against bone. There was also a moderate amount of curvature. She had absolutely no back pain. She had never had significant back pain. I performed a one level fusion at L5-S1, which relieved the pressure on the nerve. The fusion prevented the opening around her 5th nerve from collapsing when she stood up. Her leg pain is gone and she is back to full activities.
This example is extreme only in the severity of the degeneration of the discs. I see patients routinely who present with severe degeneration of their spines and have only leg symptoms
Structural versus non-structural
If you can’t specifically localize the source of pain, it would be considered a non-structural problem. Back pain almost always considered non-structural since the pain is widespread and there isn’t a reliable method to identify the “pain generator”. Surgery is helpful only for structural problems, when the offending lesion can be identified and the symptoms closely match.
The analogy I often is that of going to the dentist with a painful cavity. The source of the pain is obvious. By having the tooth repaired or pulled, the problem is solved. If you present to the dentist with mouth pain and can’t identify the source, you have to be much more careful. Random procedures in your mouth probably won’t solve the pain, since there are so many possibilities. Doing back fusions is about as successful. Most of the discs in the lower back have some degeneration. Even if you thought one of them might be the source of pain, how do you know which one it is? More invasive testing, such as injecting dye into the disc, hasn’t worked out well either.
I recall a Golf Digest article many years ago showing a famous golfer’s swing during his first years on the PGA tour compared to 20 years later. Early in his career he had a beautiful “C” shape of his lower back at the completion of his swing. Twenty years later, his lower back was almost straight throughout all the phases of his swing. None of us are as flexible in our 60’s as we were in our 20’s.
Discs can be the cause of pain in the initial acute phase of an injury. This often occurs in the presence of a relatively normally hydrated disc that has more motion than a degenerated disc. It’s felt that the ring around the perimeter of the disc is partially torn and there’s an irritation of the nerve fibers in the ring that can be quite uncomfortable. Before my first back operation, I would experience severe episodic bouts of low back pain. After the rupture of my L5-S1 disc relieved the internal pressure on the pain fibers in the ring, my back pain disappeared.
Even though discs can cause low back pain, they only do so a minority of the time. We don’t have the diagnostic tools to accurately discern the disc pain from the surrounding soft tissues as the source of pain. Even if we were certain it was the disc, we couldn’t tell which level might be causing your pain.
There are hundreds of thousands of spine fusions being performed annually in the US on degenerated discs for back pain. The results are unpredictable and people are often worse. Be careful. A spine fusion is a major intervention. You might be making the decision to have surgery performed on a structure that is completely normal for your age.
- Jensen MC, et al. Magnetic resonance imaging of the lumbar spine in people without back pain. NEJM (1994); 331:69-73.