Intervertebral Disc

The nucleus pulposus is the central, gel-like portion of the intervertebral disc, which is composed mainly of water, proteoglycans, and collagen. It functions as the primary shock absorber within the spine, redistributing mechanical forces exerted during movement. 

The high water content, which ranges from 70% to 90%, allows the nucleus pulposus to retain its cushioning properties, preventing excessive strain on surrounding spinal structures. 

Proteoglycans within the nucleus attract and retain water, ensuring the disc remains hydrated and able to resist force.

The annulus fibrosus is the tough outer layer that surrounds the nucleus pulposus, providing structural integrity to the intervertebral disc. 

Based on our observations, it is composed of 15 to 25 concentric fibrocartilaginous sheets known as lamellae, each arranged in alternating directions. 

This unique configuration enables the annulus to resist tensile forces while maintaining flexibility. The annulus primarily contains type I and type II collagen, providing strong yet elastic properties. 

These layers work together to confine the nucleus pulposus and protect the disc from excessive strain.

The vertebral endplate is a thin layer of hyaline cartilage that separates the intervertebral disc from the adjacent vertebral bodies. Our findings show that it serves two key functions: mechanical support and nutrient exchange. 

The endplate acts as a semi-permeable membrane, allowing essential nutrients such as glucose and oxygen to diffuse from the vertebral bone into the largely avascular disc. 

This nutrient flow is critical for maintaining the health of both the nucleus pulposus and annulus fibrosus.

As mentioned, intervertebral discs are largely avascular, meaning they lack a direct blood supply. Only the outermost layer of the annulus fibrosus receives blood flow, while the inner portions of the disc rely on diffusion to obtain nutrients and remove metabolic waste. 

This process occurs through the blood vessels located near the disc-bone junction and those in the outer annulus.

Because intervertebral discs lack a dedicated lymphatic system, the removal of waste products is entirely dependent on passive diffusion.

When diffusion is impaired due to aging, injury, or reduced spinal mobility, the disc becomes more susceptible to inflammation, degradation, and structural failure.

In a healthy intervertebral disc, only the outer third of the annulus fibrosus contains nerve fibers, which receive input from branches such as the sinuvertebral nerve. 

This limited innervation means that the inner two-thirds of the annulus and the nucleus pulposus are devoid of nerve fibers.

The intervertebral discs exhibit several physiologic variations based on their location within the spine. Generally, disc thickness increases near the front and tail parts of the body, with a slight decrease at the T3-T4 level. 

The cervical and lumbar discs tend to have the highest ratio of disc thickness to vertebral body height, correlating with the greater range of motion observed in these regions.

Our research indicates that the intervertebral discs are thicker anteriorly in the cervical and lumbar regions, contributing to the natural curve of the spine.

When the spine undergoes compression, the nucleus pulposus functions like a hydraulic cushion, distributing pressure in all directions. This action reduces localized stress on the vertebral endplates and annulus fibrosus. 

Meanwhile, the annulus fibrosus, with its unique layered architecture, provides strength, preventing excessive bulging or rupture of the nucleus pulposus, under healthy conditions. 

Together, these components ensure that the spine can withstand daily movements, high-impact activities, and heavy lifting.

Intervertebral disc degeneration, such as herniated disc and bulging disc, is a progressive condition that contributes to chronic back and neck pain. 

Degenerative disc disease occurs in several stages. First, a small tear occurs in the outer fibrous ring of the disc. Then this tear allows fragments of the nucleus pulposus to leak into the annular space, triggering inflammation and discogenic pain. 

More strain causes further tearing. As the annular tear expands, the disc may undergo bulging, protrusion, herniation, or extrusion, where the nucleus pulposus extends beyond its normal boundaries. 

When the protruding disc comes into contact with spinal nerves or the spinal cord, it can cause radiating pain, numbness, tingling, and weakness in the affected area. 

In severe cases, disc degeneration can lead to spondylosis (disc narrowing and osteophyte formation).

Traditional treatments for disc degeneration include physical therapy, pain medications, and steroid injections, but these methods provide only temporary relief without addressing the underlying damage.  

Similarly, surgeries like  laminectomy and artificial disc replacement come with high risks: spinal fluid leaks, wound infections, hardware failure or migration, and failed back surgery syndrome,

A superior alternative is Deuk Laser Disc Repair, which precisely removes the inflamed nucleus pulposus material from within the annular tear while preserving the healthy disc structure. 

Over 95% of chronic disc-related pain can be cured with Deuk Laser Disc Repair®, with a 0% complication rate, making it the safest treatment for disc degeneration today​.