Low Back Anatomy
Our spine is made up of 24 bones, called vertebrae, which are stacked on top of each other. Together, the vertebrae function to provide upright stability and create a structure called the spinal canal, which encases and protects the spinal cord (1). In between each vertebra are intervertebral discs which function to absorb shock as well as allow movement between the vertebrae (1). Each disc is made up of the nucleus pulposus, a jelly-like substance in the middle of the disc, and the annulus fibrosis which encases the nucleus (1). Entering and exiting at the back of each of the vertebrae are nerve roots which function to stimulate muscles for the production of movement as well as to detect sensations such as touch in our lower limbs (2). The majority of disc herniations occur in the low back. The low back consists of the lumbar spine, which is composed of 5 vertebrae, as well as the sacrum bone which contains 4 vertebrae.
What happens when a disc herniates?
A disc herniation occurs when the nucleus pulposus is forced (due to wear and tear or sudden movement) outside of the intervertebral disc space (3). This can damage or tear the outer portion of the disc, causing pain and inflammation (4). This inflammation can damage the nerve root exiting near the vertebra in which the injury occurred (4). Additionally, the disc may put pressure on the nerve root (3). These two mechanisms can cause pain in the low back which can radiate down the lower limbs (3). Loss of sensation and muscle weakness may also occur in the lower limbs (3)
Are symptoms always present with a disc herniation?
Having a disc herniation in the lumbar spine does not necessarily mean that one will experience the symptoms listed above. Disc herniations are commonly seen on MRI in individuals who experience no symptoms.
Physical Therapy Treatment
Patients with a herniation typically respond well to physical therapy treatment (6). When treating a herniation, Physical Therapists use techniques to reduce pain, improve mobility and decrease the chances of experiencing similar injuries in the future. Physical Therapists incorporate the use of modalities such as interferential current, acupuncture and dry needling; manual therapy including soft tissue, dural and fascial release, traction, mobilization and manipulation; as well as therapeutic exercise prescription to reduce pain and associated symptoms (4). Additionally, Physical Therapists can use techniques to re-train core stability muscles to prevent further injury. The re-training of these muscles allow for the stabilization of the spine and a greater degree of control over spinal movement (6).
Raj, P. P. (2008). Intervertebral Disc: Anatomy‐Physiology‐Pathophysiology‐Treatment. Pain Practice, 8(1), 18-44.
American Academy of Orthopedic Surgeons (2012, November). Herniated Disk in the Lower Back. Retrieved from http://orthoinfo.aaos.org/topic.cfm?topic=a00534
Jordan, J. L., Konstantinou, K., & O'Dowd, J. (2011). Herniated lumbar disc. BMJ clinical evidence, 2011.
Shahbandar, L., & Press, J. (2005). Diagnosis and nonoperative management of lumbar disk herniation. Operative Techniques in Sports Medicine, 13(2), 114-121.
Brinjikji, W., Luetmer, P. H., Comstock, B., Bresnahan, B. W., Chen, L. E., Deyo, R. A., ... & Wald, J. T. (2015). Systematic literature review of imaging features of spinal degeneration in asymptomatic populations. American Journal of Neuroradiology, 36(4), 811-816.
Hahne, A. J., Ford, J. J., & McMeeken, J. M. (2010). Conservative management of lumbar disc herniation with associated radiculopathy: a systematic review. Spine, 35(11), E488-E504.