A Physio’s Guide To Lumbar Disc Bulges - How to Know if You Have One.

“I think I’ve bulged my disc again” - Is this you?

As a physio, I see people with lower back pain every day. One of the more common self-diagnoses I see in practice is a disc bulge. It seems that no matter what the cause of someone’s back pain, all roads lead to a disc bulge. So today I am going to shed light on what a disc bulge is. This will help you to recognise the signs of a disc bulge and work out whether you are suffering from one or not.

While we emphasise the importance of seeking professional evaluation for an accurate diagnosis and effective treatment plan, understanding these signs can be the first step towards relief.

To recognise a disc bulge, you must first understand the anatomy of the spine.

Lumbar Spine Anatomy

The lumbar spine consists of five vertebrae, labelled as L1-L5, stacked on top of one another. Between each vertebra lies an intervertebral disc, acting much like a cushion, absorbing shock and allowing flexibility. These discs are composed of two main parts: a tough outer ring (annulus fibrosus) and a soft, gel-like centre (nucleus pulposus).

The lumbar spine is designed in a way that supports the weight of the upper body, enables movement, and protects the spinal cord all in one. It works with the sacroiliac joint (where the sacrum meets the pelvis) just below it to act as the stable foundation for the limbs to move around.

Structure of Intervertebral Discs

From Wikimedia

Annulus Fibrosus (Tough Outer Layer)

This is the disc's outer shell, made of fibrocartilage layers that provide both strength and flexibility to the spine. It’s designed to resist excessive twisting of one vertebra on another and to resist the outward pressure coming from the gel-like centre of the disc.

Nucleus Pulposus (Gel-like Center)

The centre of the disc is a jelly-like substance crucial for absorbing shock. It keeps the spine flexible and the vertebrae properly spaced. As you move in different directions, the nucleus pulposus moves as well.

Role of Intervertebral Discs

Cushioning and Shock Absorption

The discs act as the spine's shock absorbers, protecting against impacts from daily activities. Every movement you make, whether you're getting after it on your morning run or simply walking to work, generates a force that travels up your legs and into your spine. Without these gel-like cushions, each impact could lead to discomfort or even damage to your vertebrae.

Facilitating Spinal Flexibility

The stretching of the fibrocartilage outer layer of the discs allows for bending and twisting. They’re essential for our range of movement. Without them, our vertebrae would be rigidly stacked on top of one another.

Maintaining Spinal Integrity

Each disc serves as a crucial link in the chain, helping to distribute the pressures and weights we put on our spine evenly. Whether you're lifting a heavy box or sitting at your desk, your spine is under pressure. The even distribution of this pressure prevents any single part of your spine from being overloaded, which could lead to pain or injury.

What is a Disc Bulge?

From Wikimedia

A disc bulge happens when the nucleus pulposus pushes outward into the outer layers. Normally the annulus fibrosis can resist this pressure and it pushes it back in. But with a disc bulge, the inner gel-like substance pushes through the outer layers beyond its normal boundary.

But what makes this condition cause you pain? The bulging process leads to stretching or even tearing of these outer fibres, which can generate pain. On top of that, it can compress nearby nerves, causing further pain.

But what specific symptoms would someone with a disc bulge have?

Common Causes of a Disc Bulge

Understanding what leads to a disc bulge is crucial for both prevention and treatment. While some causes are part of natural aging, others are related to our lifestyle and daily activities. Let's explore the main culprits behind this common yet troublesome condition.

Aging

Let’s get the obvious one out of the way, as we get older, our discs naturally undergo a process of aging as well. This isn't about how active you are or your fitness level; it's an inevitable part of aging.

As you age, your discs lose their ability to retain water, which gradually diminishes their ability to shock-absorb. As you can imagine, this makes them more susceptible to damage and can lead to disc bulges. Think of it like an old cushion that's lost its puffiness and no longer offers the same level of comfort or support.

The impact of age on disc bugle prevalence is well documented. A 2015 study found that 37% of people in their 20s (without pain) had at least one disc bulge, while that number went up to 96% of people in their 80s (again, without pain). If you want to learn more about this particular study and why you shouldn't believe everything you read on your scans, click here.

Improper Lifting Techniques

How you lift matters. Lifting heavy objects without hinging at your hips is a bad habit that will place excessive stress on the back part of the disc.

You will remember that your discs are designed to change shape. As you flex your spine (bending forward), the inner part of the disc moves backward. Doing this while picking up light objects won’t cause any lasting issues, but with a heavy load, the pressure might be enough to push the centre of the disc hard enough to strain some of the outer fibres.

Repetitive Strain from Daily Activities

It's not just what you do here and there that affects your discs.

Actions that you only do on odd occasions are often harmless. What you do repetitively or for long periods is what matters more. Prolonged sitting, especially with poor posture, repetitive bending with load or lifting with a rounded back, are actions that put continuous strain on your discs. Over time, these repetitive actions add up and lead to a disc bulge.

Common Symptoms of a Disc Bulge

Identifying the symptoms of a disc bulge can be the first step towards getting the right help and starting on the path to recovery.

We don’t need fancy tests or an X-ray to diagnose a disc bulge. A skilled physiotherapist can determine your injury by your symptoms alone. So let's go through some common signs that might indicate a disc bulge.

Pain With Bending

A disc bulge is caused by the inner gel-like part of the disc pushing out of its normal boundary and stretching the outer disc layers.

Bending or flexing the lumbar spine places a backward force on the inner part of the disc, pushing it out towards the stretched and sensitive outer layers of the disc. This results in a reproduction of pain.

Weakness With Bending

Often, when I ask a person with a disc bulge to bend it will involve them walking their hands down their thighs, bending their knees to take the weight, and very limited lower back bending will occur.

This weakness when bending is a protective response from the brain. It’s caused by a global muscle spasm to protect the lower back. Because the brain knows that bending is an aggravating action, it causes the muscle spasm to reduce movement between the vertebrae, thus reducing movement of the discs.

Broad Pain Distribution

The pain you will feel in the initial stages of a disc bulge is broad spread, rather than being focused on a single point. The main reason for this is the global muscle spasm in the area that happens to protect the lower back from re-injury.

Referral/Radiating Pain

When a disc bulge irritates the spinal nerves you can get pain that spreads beyond the lower back, down into the buttock and the legs.

The irritation can be caused by several factors: actual compression of the nerve from the bulge, compression caused by the acute swelling, or chemical irritation from the inflammatory molecules.

The type of referral pain is important. Rather than a vague and undefined pain distribution, the pain that travels down the leg in a disc bulge follows a particular pattern. This is known as radicular pain (often referred to as sciatica).

Below is a model that shows the approximate distributions of radicular pain based on the spinal nerve affected.

From Wikimedia

Do You Have A Disc Bulge?

If your answer to most of these was: “Yep, that’s me” - you MAY have a disc bulge. But as always, I would advise consulting a health professional to get a definitive diagnosis.

Let’s say that you do have a disc bulge, does that mean you need surgery? Hell no!

All the evidence suggests that a conservative approach to rehabbing a disc bulge, meaning exercise and activity modification, is just as effective as surgery. The key to a successful recovery is understanding what a disc bulge is (which you should be on top of by now), learning how to retrain your pain system, strengthening your muscles back to where it was before you hurt yourself, and reintegrating exercise and physical activity back into your life.

If you have a disc bulge and would like to be guided along the path to being pain-free. CLICK HERE to book a free discovery call with Nathan (Founder and Physiotherapist) to see whether you would be a great fit for our program.