Degenerative Disc Disease
What Causes Degenerative Disc Changes and Chronic Low Back Pain?
Degenerative disc disease (DDD) is a term generally applied to degenerative changes seen in the intervertebral disc in patients that have low back pain. In some people, the affected disc can be the source of pain. Such patients have discogenic low back pain (dLBP). Figure 1 provides an overview of the anatomy of a healthy intervertebral disc.
Figure 3. (Click image to enlarge.)
Figure 1. (Click image to enlarge.)
Figure 2. (Click image to enlarge.)
Figure 4. (Click image to enlarge.)
Healthy intervertebral discs act like shock absorbers for the spine (Figure 2), however, as the body ages, degenerative changes occur as part of the body and tissue’s normal wear and tear. Furthermore, the cause of dLBP may be directly related to injury sustained by the nucleus pulposus (NP). This injury can be due to excessive wear and tear from poor biomechanics or any significant accident or injury. The damage to the disc leads to inflammation within the NP and microtearing of the annulus of the disc that contains the nucleus. The nucleus tissue has poor blood supply and inflammation takes very long to resolve, if it can be resolved at all. Additionally, abnormally sensitive nerve endings grow into these microtears and render the disc hypersensitive to movements that do not otherwise cause pain. Other spinal elements may be affected as degeneration progresses. Figure 3 illustrates some of the degenerative changes that might occur within the lumbar spine.
Degenerative disc changes are often characterized by a loss of water content in the disc (confirmed using a T-2 weighted MRI sequence — see Figure 4) and various changes to its elastic and mechanical properties. This can lead to dLBP. It is important to note that although degenerative changes may be observed, the pain may be unremarkable. Conversely, imaging may reveal very mild degenerative changes, yet the patient may be experiencing significant pain.
There are numerous treatments for dLBP ranging from conservative therapies such as physical therapy and nonsteroidal anti-inflammatory drugs (NSAIDS), to more invasive surgical options such as spinal fusion, total disc replacement, and Nucleus Replacement in appropriate patients. See Treatment Options for more information.