What Is Degenerative Disc Disease?

Degenerative disc disease (DDD) is a condition where one or more intervertebral discs deteriorate, causing pain (usually in the lower back or neck) with or without acute sciatica. The condition is also referred to as disc degeneration or intervertebral disc degeneration. When affecting the lower back specifically, it may be called lumbar disc disease; in the neck, cervical disc disease.

There is no universal medical definition. Some doctors apply the term to any visible disc changes; others reserve it for cases causing significant symptoms. Here, we use it to mean lumbar disc deterioration that results in persistent symptoms and acute pain.

Intervertebral discs wear out over time and dehydrate, causing the gel-like nucleus pulposus to escape. This in turn allows the disc to move from its natural position, often causing inflammation or compressing spinal nerves.

When this degeneration is sufficient to cause symptoms, it’s termed degenerative disc disease. Contributory factors include natural ageing, genetics, spinal injuries, smoking, and occupations involving heavy lifting or prolonged sitting.

What Are Intervertebral Discs?

Intervertebral discs are the shock-absorbing structures between vertebrae. Each has a tough exterior and a soft gel-like centre (the nucleus pulposus). The lumbar spine’s five discs support most of the body’s weight, making them especially susceptible to wear.

What Happens When Discs Degenerate?

As discs degenerate, they dehydrate and compress under the weight of the vertebrae above and below. The outer layer may develop tears, allowing the nucleus pulposus to leak out and the disc casing to bulge. Disc material pressing on the lower spinal nerve roots causes sciatica, a pain that follows the path of the sciatic nerve down the leg.

Almost everyone develops some disc degeneration with age. Most never notice. The term degenerative disc disease is typically applied when degeneration causes ongoing symptoms, which affects a minority.

In our experience, up to 10% of patients experience symptoms which get that progressively worsen and require surgical intervention, such as total lumbar disc replacement.

The main symptoms of lumbar degenerative disc disease are lower back pain and sciatica. Symptoms often fluctuate, with flare-ups triggered by activity or sustained postures, and periods of relative relief. Over time, a minority of patients experience an increased frequency of episodes with more acute symptoms that cannot be managed by medication and physical therapies.

For this group, symptoms have a detrimental effect on their quality of life, making routine daily activities, sleeping, and working difficult, if not unbearable.

Treatment begins with conservative measures: including pain medication, physiotherapy, and activity modification, typically trialled for several months. Surgery is considered when these approaches are ineffective in adequately controlling symptoms. Options include steroid injections (which provide temporary relief from inflammation), discectomy (which relieves nerve compression and may provide temporary relief of symptoms), spinal fusion, and Prodisc® L total lumbar disc replacement.

Several terms overlap with degenerative disc disease, which can cause confusion.

A herniated disc occurs when the gel-like nucleus pulposus pushes through a tear in the disc’s outer layer, deforming the disc and allowing it to move from its natural position. This can cause symptoms such as acute lumbar back pain and sciatica. Slipped disc means the same thing.

Herniation is often a consequence of disc degeneration, but not everyone with degenerative disc disease develops a herniation.

Sciatica refers to pain radiating from the lower back into the buttock and leg, following the path of the sciatic nerve. It is a symptom rather than a diagnosis, and disc herniation is one of its most common causes.