Musculoskeletal · Patient education from the Pegasus Peak physiotherapy team.
Reviewed by the Pegasus Peak physiotherapy team — AHPRA-registered physiotherapists led by principal physiotherapist Kosta Logothetis. Last reviewed 2026-02-28.
What a herniated disc is, how it happens, common types, and why most cases improve with proper load management and rehab.
A herniated disc refers to an injury involving one of the intervertebral discs of the spine.
A herniated disc refers to an injury involving one of the intervertebral discs of the spine. When this occurs, part of the disc moves beyond its normal boundary. In some cases, this displaced material can irritate or compress nearby structures such as a nerve root, leading to pain, numbness, tingling, or weakness in the arm or leg.
Not all disc herniations cause symptoms. Many are completely painless.
Each intervertebral disc is made up of three key structures.
The nucleus pulposus is the soft, gel-like centre of the disc. It contains a high water content, allowing it to absorb compressive forces and distribute load evenly through the spine. This structure is what gives the disc its shock absorbing ability (Adams & Roughley, 2006; Raj, 2008).
The annulus fibrosus is the strong outer ring that surrounds the nucleus. It is made of layered collagen fibres arranged in alternating directions, which provides both strength and flexibility. Its job is to contain the nucleus and control movement during bending, lifting, and twisting (Adams & Roughley, 2006).
Each disc is capped above and below by thin cartilage layers called vertebral endplates. These bind the disc to the vertebral bodies and allow nutrients to pass into the disc, which does not have a direct blood supply. They also help spread load across the disc evenly (Roberts et al., 2006).
Intervertebral disc anatomy
Discs are designed to handle load. Like any structure in the body, they adapt when stressed appropriately. Problems tend to arise when the load placed on the disc exceeds what it is prepared to tolerate.
This can happen with:
It is not that bending or twisting is “bad.” The issue is whether the tissue is conditioned for that load.
It is also important to understand imaging findings. Research shows that many people without back pain have disc bulges or protrusions on MRI scans (Brinjikji et al., 2015). This means the presence of a disc herniation on imaging does not automatically indicate the source of pain.
In fact, discs are most likely to be the primary pain generator in more acute presentations, particularly when symptoms include sharp back pain with associated nerve irritation. In longer lasting cases, other contributing factors such as movement sensitivity, deconditioning, or central sensitisation may play a larger role.
While the terminology can sound technical, the concept is simple: the disc can shift slightly or more significantly.
A bulge is when the disc slightly extends beyond its normal boundary, but the outer ring remains intact. Think of it as a general widening of the disc.
A protrusion occurs when part of the inner gel pushes into the outer ring, creating a more focal bump. The outer fibres are still mostly intact.
An extrusion happens when the inner gel pushes through a tear in the outer ring but remains connected to the disc.
A sequestration occurs when a fragment of the inner gel completely breaks off and moves into the spinal canal.
The more advanced types, such as extrusion and sequestration, may take longer to settle, particularly if nerve irritation is involved. However, even these can improve without surgery (Chiu et al., 2015).
The discs are supported by both passive and active structures.
Passive structures include ligaments that limit excessive spinal movement.
The posterior longitudinal ligament runs along the back of the vertebral bodies and helps control forward bending.The anterior longitudinal ligament runs along the front of the spine and helps limit excessive backward bending (Bogduk, 2005).
These structures provide stability without requiring muscular effort.
Active support comes from muscles surrounding the spine, particularly the erector spinae and deep paraspinal muscles.
These muscles help control spinal movement and distribute load during lifting, bending, and daily tasks. If these muscles lack strength or endurance relative to the task being performed, more stress may be transferred to passive structures such as the discs.
Acute disc injuries often occur not because bending forward is inherently harmful, but because the overall load exceeds the combined capacity of both muscular and disc tissues.
We will delve more in depth into treatment in a subsequent post. However, most disc injuries follow a predictable recovery pattern.
Research shows that many herniated discs reduce in size or reabsorb naturally over time, especially extrusions and sequestrations (Chiu et al., 2015).
In the early stages, treatment typically focuses on:
For most individuals, symptoms improve significantly within 6 to 12 weeks (Fardon et al., 2014).
If symptoms persist beyond expected tissue healing time, central sensitisation may contribute. In these cases, education, graded exposure, and progressive loading remain central to recovery.
Surgery is generally reserved for cases involving progressive neurological deficit, significant weakness, or persistent nerve compression that does not respond to conservative care.
A herniated disc refers to displacement of disc material beyond its normal boundary. While this can irritate nearby nerves and cause pain, disc changes are common and often painless. The presence of a herniation on imaging does not automatically mean it is the source of symptoms. Discs are designed to tolerate load, and injury often reflects a mismatch between load and capacity. With appropriate management, most disc injuries improve over time without surgical intervention.
Adams, M. A., & Roughley, P. J. (2006). What is intervertebral disc degeneration, and what causes it?Spine, 31(18), 2151–2161.https://doi.org/10.1097/01.brs.0000231761.73859.2c
Bogduk, N. (2005).Clinical anatomy of the lumbar spine and sacrum(4th ed.). Elsevier.
Brinjikji, W., Luetmer, P. H., Comstock, B., Bresnahan, B. W., Chen, L. E., Deyo, R. A., Halabi, S., Turner, J. A., Avins, A. L., James, K., Wald, J. T., Kallmes, D. F., & Jarvik, J. G. (2015). Systematic literature review of imaging features of spinal degeneration in asymptomatic populations.AJNR American Journal of Neuroradiology, 36(4), 811–816.https://doi.org/10.3174/ajnr.A4173
Chiu, C. C., Chuang, T. Y., Chang, K. H., Wu, C. H., Lin, P. W., & Hsu, W. Y. (2015). The probability of spontaneous regression of lumbar herniated disc: A systematic review.Clinical Rehabilitation, 29(2), 184–195.https://doi.org/10.1177/0269215514540919
Fardon, D. F., Williams, A. L., Dohring, E. J., Murtagh, F. R., Gabriel Rothman, S. L., & Sze, G. K. (2014). Lumbar disc nomenclature: Version 2.0: Recommendations of the combined task forces of the North American Spine Society, the American Society of Spine Radiology, and the American Society of Neuroradiology.The Spine Journal, 14(11), 2525–2545.https://doi.org/10.1016/j.spinee.2014.04.022
Raj, P. P. (2008). Intervertebral disc: Anatomy–physiology–pathophysiology–treatment.Pain Practice, 8(1), 18–44.https://doi.org/10.1111/j.1533-2500.2007.00171.x
Roberts, S., Urban, J. P. G., Evans, H., & Eisenstein, S. M. (2006). Transport properties of the human cartilage endplate in relation to its composition and calcification.Spine, 21(4), 415–420.
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