13 Jun Understanding L4/L5 and L5/S1 Disc Herniations: Causes, Symptoms, and Solutions
Article Rundown
- L4/L5 and L5/S1 disc herniations are the most common and often cause confusing symptoms like foot pain or hamstring burning.
- Disc damage often begins with endplate injuries and leads to instability, loss of height, and stress on nearby joints.
- Herniated discs can compress nearby nerve roots, leading to pain, numbness, or weakness down the leg.
- Many herniations can heal naturally over time with proper movement, posture, and inflammation management.
Why L4/L5 and L5/S1 Disc Issues Are So Common
If you’ve ever reached out to me and said, “Brian, I’ve got an L4/L5 or L5/S1 disc bulge—what do I do?” you’re not alone. These are the two most commonly affected areas of the spine when it comes to disc herniations and bulges, and the symptoms can be confusing.
You might feel pain in your foot and think it’s plantar fasciitis, or you might have burning in your hamstrings and glutes and assume it’s sciatica. But in many cases, these symptoms trace back to instability or damage at the base of your spine, specifically the L4/L5 and L5/S1 vertebral segments.
The Anatomy of the Problem
Let’s break it down anatomically. The lumbar spine ends at L5, which sits just above the sacrum. The discs between these vertebrae (L4/L5 and L5/S1) serve as crucial shock absorbers. When these discs are healthy, they maintain height and spacing between vertebrae, allowing for smooth motion and nerve passage.
But when instability sets in—either from compression, overuse, or trauma—the vertebrae can begin to shift. Over time, micro-movements from that instability cause stress concentrations. This is where you’ll see the facets (the small joints at the back of the spine) begin to grind, especially during extension movements.
Disc Damage and Degeneration
Using dynamic spine models like those from Dynamic Disc Designs (some of the best in the world, by the way), you can clearly see the progression. A healthy disc has height, hydration, and a strong nucleus in the center. But once the endplates (the cartilage layers connecting discs to vertebrae) take damage, say from a fall or long-term heavy loading, the disc can begin to flatten or bulge.
This loss of disc height is the beginning of what’s often labeled degenerative disc disease. Like a tire slowly leaking air, the disc loses its structure. The vertebrae start to change their alignment, and the joints begin to bear more load than they’re meant to.
Eventually, you may see:
- Bone-on-bone mechanical collision
- Arthritic changes in the joints
- Bony growths (osteophytes)
- Narrowing of the foramen (where nerves exit)*
- Narrowing of the spinal canal (where the thecal sac is) *
- And much more…..
Disc Herniations and Nerve Involvement
One of the most important details is what happens when the nucleus (the gel-like center of the disc) works its way through the tough outer layer, the annulus fibrosus. This outer layer is made up of multiple layers of woven collagen, and when it tears, the nucleus can protrude, causing a true disc herniation.
These herniations can push on the exiting nerve roots, such as the L4 nerve, which runs through the foramen right next to the disc. If the herniation is central or paracentral, it can compress the thecal sac (which houses the spinal cord and nerve roots) and cause pain, numbness, or weakness downstream—sometimes all the way to the feet.
The Role of the Facet Joints
As disc height decreases and vertebrae shift, the facet joints are forced to take more stress. These joints guide flexion and extension, but when overloaded, they become inflamed and begin to degenerate. This leads to further narrowing of the nerve passageways and can add to your symptoms even after the disc herniation has stabilized.
Interestingly, the facet joints can also retain fluid and become swollen, creating additional compression on nearby nerves.
Can a Herniated Disc Heal on Its Own?
Yes—many disc herniations can heal with time and the right approach. The body has natural inflammatory processes that, when not constantly irritated, can actually break down and resorb herniated disc fragments. This is especially true for “sequestered” disc material that has broken free from the main disc.
In some cases, the disc material can even “vacuum” back in if the annular tear seals and the pressure normalizes. This is why exercises like tummy-lying (or prone positions) discussed in Back Mechanic can be so beneficial—they encourage disc material to centralize and reduce nerve compression.
Takeaways for Healing and Recovery
If you’re dealing with L4/L5 or L5/S1 disc pain, don’t panic. But also don’t ignore it.
- Learn about your specific movement triggers
- Avoid repeated bending and compressive loads in the acute phase
- Use appropriate postures (like prone lying or walking) to reduce symptoms
- Seek guidance from a clinician who understands spine mechanics (and not just quick-fix treatments)
Most importantly, give your body the space and time to heal—don’t rush the process. With a smart, disciplined approach, many people recover fully and return to performance without surgery.
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