Disc Anatomy and Function
The spine is composed of two main structural components: (1) vertebrae and (2) intervertebral discs.
- The vertebrae are the bones of the spine that function to protect the spinal cord and support the upper body.
- Each vertebra is separated by an intervertebral disc which acts to cushion against impact and provide flexibility to support your body’s ability to bend and rotate.1
The intervertebral disc (IVD) consists of three regions, the anulus fibrosus (AF), the nucleus pulposus (NP) and the cartilaginous endplate.2
The AF is a fibrous outer ring of collagen fibers that functions as the primary load-bearing component of the IVD.3
The NP is a hydrophilic gelatinous core comprised primarily of proteoglycans, collagen II, water and cells. The healthy NP contains ~77% water, and the high-water content provides the mechanical function of absorption and redistribution of spinal loads.4
The endplates permit diffusion and provide the main source of nutrition for the disc.5
Characteristics of Degenerated Discs
Degenerated discs are characterized by decreased disc height, loss of water content and loss of nutrient content.
These functional biomechanical alterations present as cracks and fissures within your disc. Altogether, the structural changes in the degenerated disc strain the nerves, put focal pressure on the spine and ultimately cause pain.1,6,7
Common Causes of Chronic Back Pain
Discogenic Low Back Pain
Discogenic low back pain can be determined through a combination of symptoms, physical examination and imaging. Pain typically manifests itself as medial back pain with or without radicular leg pain. Further identification focuses on determining the directional forces that worsen symptoms.With discogenic low back pain, shear forces push down and load the spine, applying pressure to the disc. Therefore, pain is exacerbated most when leaning forward as this weight-bearing position puts the most pressure on the painful disc.
Confirmation of pathology via imaging is important to ensure disc degeneration is present. The Pfirrmann grading scale rates severity of disc degeneration on a scale of 1-8 based on MRI signal intensity, disc structure, distinction between nucleus and anulus, and disc height. Pfirrmann scores from 1-8 represent a progression from normal disc structure to severe disc degeneration, and thus discogenic low back pain can be confirmed structurally via MRI.
- Other Factors
Once discogenic low back pain symptoms are matched with confirmatory imaging, certain other factors must be assessed to determine the most favorable treatment options. Such factors include, but are not limited to, spondylolisthesis, translation, grade III modic changes, disc extrusion and/or neural compression.
Current Treatment Options
Non-invasive treatments for low back pain to improve symptoms. Most episodes of low back pain can be treated through conservative care to alleviate pain and manage discomfort
- Physical Therapy
May include coordination, strengthening, and endurance therapy
- Chiropractic Treatment
May include acupuncture, massage, spinal manipulation and other chiropractic procedures
May include prescribed acetaminophen, NSAIDS, skeletal muscle relaxants, antidepressants, antiepileptic drugs, benzodiazepines, tramadol, opioids and/or systemic corticosteroids
- Radio Frequency Ablation (RFA)
Procedure that involves heating a pain-stimulating nerve to create a heat lesion, preventing the nerve from sending pain signals to the brain
- Epidural Steroid injections (ESIs)
Injection of a steroid into the epidural space to manage acute pain and provide temporary relief
- Lumbar Fusion
Invasive surgical procedure designed to stop motion at a painful vertebral segment through fusion of adjacent vertebrae
- Lumbar Disc Replacement
Replacement of a degenerated disc with a synthetic disc designed to allow for motion and decreases stress on the disc at the next level
1. Zhu, Qiaoqiao: Numerical Modeling of Intervertebral Disc Degeneration and Repair (2016). Open Access Dissertations. Paper 1594.
2. Walter BA, Torre OM, Laudier D, Naidich TP, Hecht AC, Iatridis JC. Form and function of the intervertebral disc in health and disease: a morphological and stain comparison study. J Anat. 2015;227(6):707–716.
3. Lundon K, Bolton K. Structure and Function of the Lumbar Intervertebral Disk in Health, Aging, and Pathologic Conditions. J Orthop Sports Phys Ther. 2001;31(6):291-306.
4. Chen S, Fu P, Wu H, Pei M. Meniscus, articular cartilage and nucleus pulposus: a comparative review of cartilage-like tissues in anatomy, development and function. Cell Tissue Res. 2017;370(1):53–70.
5. Adams MA, McNally DS, Dolan P. 1996. Stress’ distributions inside intervertebral discs. The effects of age and degeneration. J Bone Joint Surg Br 78-B:965–972.
6. Setton L, Chen J. Cell mechanics and mechanobiology in the intervertebral disc. Spine 2004; 29(13): 27, 10–23.
7. Peng B, Wu W, Hou S, et al. The pathogenesis of discogenic low back pain. J Bone Joint Surg 2005; 87: 62–7.