The term mechanical low back pain is used very often, but its meaning is not always clear. Despite the name, this condition has nothing to do with automobile mechanics or people who work with machines. Instead, the word “mechanical” refers to pain that comes from the structures that make up the spine and surrounding tissues.

The problem is that different doctors and patients may intend different things when they use this term. There is no single universally accepted definition. Because of this, the phrase can sometimes create confusion instead of improving understanding.

In many cases, the purpose of using the term mechanical low back pain is to separate it from what might be called “electrical low back pain.” This is not a common medical term, but it implies pain caused by irritation or injury to nerve tissue. Mechanical pain generally involves structures such as discs, joints, ligaments, muscles, and tendons, while electrical pain suggests that nerves are involved.

Understanding the possible meanings of mechanical low back pain can help patients appreciate why an accurate diagnosis is so important.

Three Common Interpretations of Mechanical Low Back Pain

1. Pain Coming From the Moving Parts of the Spine

The most common interpretation is that mechanical low back pain comes from the structures that normally move and support the spine. These structures include:

• Intervertebral discs
• Facet joints
• Ligaments
• Muscles
• Tendons
• Fascia

Under this definition, the pain usually becomes worse with certain movements, positions, bending, lifting, twisting, or prolonged sitting. Symptoms may improve with rest or changes in posture.

Structures specifically excluded from this interpretation include:

• Spinal cord
• Nerve roots
• Peripheral nerves

In other words, numbness, tingling, burning pain, or weakness would suggest nerve involvement rather than purely mechanical pain.

2. Pain Without Significant Nerve Compression

Another interpretation defines mechanical low back pain as pain that does not involve major nerve irritation. Under this definition, even though the discs, joints, and muscles may be injured, there is no substantial pressure on the nerves.

Included structures are:

• Lumbar discs
• Facet joints
• Sacroiliac joints
• Muscles
• Ligaments

Excluded structures are:

• Sciatic nerve
• Spinal nerve roots
• Cauda equina
• Spinal cord

This distinction is important because treatments directed at nerve pain are often different from treatments aimed at mechanical pain.

3. Pain Caused by Structural Problems Rather Than Disease

Some physicians use the term mechanical low back pain to distinguish it from pain caused by other conditions such as:

• Infection
• Cancer
• Fractures
• Inflammatory arthritis
• Kidney disease

Under this interpretation, virtually any pain generated by the normal structures of the spine may be called mechanical, even if inflammation is present.

Sources of Mechanical Low Back Pain

Several different structures in the lower back can generate pain.

Lumbar Disc Pain

L1-L2,  L2-L3,  L3-L4,  L4-L5,  L5-S1

Between each pair of vertebrae sits an intervertebral disc. The disc consists of two major components:

• The nucleus pulposus, which is a soft gel like center.
• The annulus fibrosus, which is a series of tough outer layers surrounding the nucleus.

The discs function as shock absorbers and allow movement of the spine.

Disc Fissures and Mechanical Pain

Small tears in the annulus fibrosus are called annular fissures. These fissures can become painful because the outer layers of the disc contain pain sensing nerve fibers.

When a fissure develops, movement of the spine can place stress on the damaged area and trigger pain. Sitting, bending forward, lifting objects, and twisting may increase symptoms.

The Inflammatory Component

Disc pain is not always purely mechanical. The nucleus pulposus contains inflammatory chemicals. If these chemicals leak through a fissure and enter the epidural space around the nerves, inflammation may develop.

This inflammatory reaction can irritate nearby nerve roots even when there is little or no mechanical compression. Patients may experience symptoms that resemble sciatica.

Thus, lumbar disc problems can produce both mechanical pain and an inflammatory component.

Nonsurgical Treatment of Disc Pain

Targeted exercises often focus on improving spinal stability and reducing stress on the discs. These may include:

• Walking programs
• Core strengthening exercises
• McKenzie extension exercises
• Abdominal stabilization exercises

Injection therapies may include:

• Epidural steroid injections
• Platelet rich plasma injections
• Bone marrow concentrate injections

Another nonsurgical option is the Discseel procedure. Discseel is designed to address annular fissures by using fibrin, an FDA approved biologic made from human blood. The goal is to seal fissures and stimulate healing within the disc. This treatment is performed without spine surgery.

Facet Joint Pain

Facet joint use the same numbering system as the discs:  L1-L2,  L2-L3,  L3-L4,  L4-L5,  L5-S1

Facet joints are small joints located behind the discs. These joints guide movement and provide stability.

Like the knee or shoulder, facet joints contain cartilage and can develop arthritis over time. Facet joint pain often becomes worse when standing, arching backward, or rotating.

Exercises for Facet Joint Pain

Helpful exercises may include:

• Gentle stretching
• Core strengthening 
• Posterior Pelvic tilts
• Hip strengthening
• Postural exercises

Injection Therapy

Nonsurgical treatment options include:

• Facet joint injections
• Medial branch nerve blocks
• Radiofrequency ablation
• Platelet rich plasma injections

Sacroiliac Joint Pain

The sacroiliac joints connect the spine to the pelvis. Although they move only slightly, these joints transfer forces between the upper body and legs.

Pain from the sacroiliac joints may mimic lumbar disc pain and may extend into the buttock or upper thigh.

Exercises for Sacroiliac Joint Dysfunction

Treatment often includes:

• Gluteal strengthening
• Hip stabilization exercises
• Stretching of the hip flexors
• Pelvic stabilization exercises

Injection Therapy

Common nonsurgical treatments include:

• Corticosteroid injections
• Platelet rich plasma injections
• Prolotherapy

Muscle and Ligament Pain

Muscles and ligaments help support the spine. Strains and overuse injuries are common causes of low back pain.

These injuries are often triggered by:

• Heavy lifting
• Poor posture
• Repetitive bending
• Sudden twisting movements

Targeted Exercise

Treatment usually focuses on:

• Stretching
• Core strengthening
• Aerobic conditioning
• Postural correction
• Flexibility exercises

Injection options may include:

• Trigger point injections
• Platelet rich plasma injections
• Prolotherapy

Mechanical Versus Electrical Low Back Pain

Although the phrase “electrical low back pain” is not commonly used, it can help explain the difference between pain arising from structures and pain involving nerves.

Electrical pain tends to produce symptoms such as:

• Burning sensations
• Tingling
• Numbness
• Pins and needles feelings
• Shooting pain
• Weakness

These symptoms suggest irritation or injury involving nerve tissue.

Mechanical pain, on the other hand, is often described as:

• Aching
• Stiffness
• Sharp pain with movement
• Pain related to posture
• Pain that changes with activity

However, many patients have a combination of both types of pain. For example, a leaking disc may create mechanical pain from the annular fissure while also causing inflammation around nearby nerve roots.

Why an Accurate Diagnosis Matters

Because the term mechanical low back pain means different things to different people, the phrase itself does not provide a precise diagnosis. Two patients with the same label may have completely different underlying causes.

One patient may have facet arthritis. Another may have a painful disc fissure. A third may have sacroiliac joint dysfunction. Still another may have several conditions occurring at the same time.

This is why a thorough evaluation by a spine specialist is more important than the label itself. A physician who understands the many contributors to spine pain can determine which structures are involved and recommend the most appropriate treatment.

Mechanical low back pain is not one disease. It is a broad description that includes several possible pain generators. Understanding the anatomy behind the pain allows treatment to be tailored to the individual patient. With modern nonsurgical options including targeted exercise programs, injection therapy, and procedures such as Discseel for annular fissures, many patients can achieve significant improvement without undergoing spine surgery.