Skip to Content

What is L4-L5 disc bulge?

A L4-L5 disc bulge refers to a protrusion of the disc between the 4th and 5th lumbar vertebrae in the lower back. The L4 and L5 vertebrae are located in the lumbar region of the spine, which bears most of the body’s weight. A disc bulge at this level can cause pain and other symptoms in the lower back, buttocks, and legs. Disc bulges are relatively common and often result from aging and wear and tear on the spine over time. However, bulging discs can also occur due to injury or improper lifting and movement. Understanding what a L4-L5 disc bulge is and what causes it is important for preventing and managing this common lower back condition.

What is a spinal disc?

The spine is made up of 33 vertebrae or bones that stack on top of each other to form the spine’s natural S-shaped curves. Between each vertebra is a disc composed of a tough outer layer called the annulus fibrosus and a soft, gelatinous inner layer called the nucleus pulposus. These intervertebral discs act as shock absorbers for the vertebrae, allowing the spine to flex and absorb force. They also allow for spine movement and prevent the vertebrae from rubbing against each other during movement.

Each disc is named for the two vertebrae it separates. For example, the L4-L5 disc sits between the L4 and L5 lumbar vertebrae. These particular vertebrae reside in the lower back between the highly mobile lumbar section of the spine and the more rigid sacral section.

Main functions of spinal discs:

  • Act as shock absorbers between vertebrae
  • Allow for flexion, extension, and twisting motions of the spine
  • Maintain proper spine alignment and spacing between vertebrae
  • Absorb weight and distribute pressure evenly across the spinal column

Healthy intervertebral discs allow for a wide range of motion and flexibility in the spine while protecting the vertebrae. However, injury, strain, or degeneration can damage discs over time.

What is a disc bulge?

A disc bulge refers to a localized out-pouching or protrusion of the disc beyond its normal margins. This occurs when the inner nucleus pulposus pushes through a weak spot or tear in the outer annulus fibrosus. The gelatinous nucleus material can bulge to one side and put pressure on nearby spinal nerves.

Bulging discs are common in the lower lumbar region, especially at L4-L5 and L5-S1 levels below the natural curve in the lumbar spine. This area withstands significant forces from body weight, movement, and strain. A disc bulge alone may not cause pain if it does not impinge on nerves. However, bulges can progress to more serious conditions like herniations or ruptures.

Signs and symptoms of a L4-L5 disc bulge:

  • Lower back pain on one side or both sides
  • Pain, numbness or tingling in the buttocks, thighs, calves, or feet (sciatica)
  • Muscle spasms in the low back, legs, or feet
  • Leg pain worse with sitting, bending, coughing, or sneezing
  • Weakness or decreased reflexes in one leg
  • Pain when lifting, twisting, bending forward

Symptoms often depend on the direction a disc bulges and whether it compresses a nerve root. For example, a far lateral L4-L5 disc bulge can compress the L5 nerve and cause weakness in extending the big toe and lifting the foot. Central bulges may not impinge nerves but can progress to more diffuse disc herniations.

Always seek medical care for acute, severe, or progressive back pain and neurological symptoms. Early diagnosis and treatment is key to preventing permanent nerve damage.

Causes and Risk Factors

A number of factors can contribute to L4-L5 disc bulges, including:


Discs naturally lose hydration and elasticity over time. By age 60, most people show some evidence of disc degeneration that can lead to bulging or herniation.


Sudden trauma from a fall or accident can damage discs. Even repetitive minor strains can weaken discs over time. Twisting while lifting is a common cause of disc injury.

Poor posture

Excess sitting, improper bending, heavy lifting, or bad posture adds increased pressure on lumbar discs. This accelerates disc degeneration and injury.


Excess body weight increases stress on the lumbar discs. This is linked to higher rates of disc bulges and herniations.


Smoking impairs blood flow to discs and depletes nutrients. This can accelerate disc degeneration.


Some people inherit weaker connective tissues that make discs more susceptible to injury and degeneration.

Diagnosing a L4-L5 Disc Bulge

If a L4-L5 disc bulge is suspected based on symptoms, a physician will perform a physical exam and order imaging tests. These may include:

  • MRI – Best for visualizing soft tissues like disc bulges, herniations, or nerve impingement. MRIs can detect even small disc abnormalities.
  • CT scan – Uses X-rays and may be ordered if MRI is not possible. A CT myelogram injects dye to improve spinal canal visualization.
  • X-ray – Shows disc space narrowing and changes in vertebrae shape but does not image soft tissues well.
  • Electromyography – Measures electrical activity in muscles and nerve conduction. Can confirm nerve root compression.

Results from a combination of tests allow doctors to confirm the location and extent of disc bulging and whether surgery or conservative treatment is warranted.

L4-L5 Disc Bulge Treatment

Mild to moderate L4-L5 disc bulges without neurological deficits can be managed conservatively with:

  • Rest – Avoid strenuous activity for 1-2 days to allow inflammation to decrease.
  • Ice/heat – Apply ice packs for 20 minutes several times per day to relieve pain and inflammation. Heat packs can also relax muscles.
  • OTC medications – Anti-inflammatories like NSAIDs (ibuprofen, naproxen) can ease acute back pain and stiffness.
  • Physical therapy – Stretching, strengthening exercises, manual therapy, and modalities help resolve muscle spasms and improve mobility.

For severe, chronic pain, options include:

  • Epidural steroid injections – Corticosteroid injections can reduce inflammation pressing on spinal nerves.
  • Surgery – Discectomy or laminectomy procedures may be needed to remove disc fragments and decompress nerves.
  • Spinal fusion – Fusing together vertebrae may be warranted if discs are severely damaged.

Surgery is generally a last resort reserved for severe neurological symptoms, bowel/bladder dysfunction, or debilitating pain.

Home remedies and lifestyle modifications

Along with medical treatment, try:

  • Cold pack wraps or ice massages for pain as needed
  • Low-impact cardio like swimming to stimulate blood flow
  • Over-the-counter pain relievers for flare-ups
  • Firm mattress and lumbar support cushion while sitting
  • Weight loss to reduce pressure on the lumbar discs
  • Quit smoking to optimize disc health and recovery
  • Physical therapy exercises to strengthen core and improve mobility
  • Stretching hip flexors, hamstrings, and muscles around the spine
  • Posture correction when sitting, standing, and sleeping
  • Avoid prolonged sitting and repetitive bending or twisting
  • Use proper lifting techniques – bend knees, keep back straight
  • Lose weight if overweight or obese to reduce lumbar disc stress

With conservative treatment, most mild to moderate L4-L5 disc bulges resolve within several weeks to months. However, bulges that compress nerves may require surgical intervention.


L4-L5 disc bulges are common causes of acute and chronic low back pain. Aging, injury, poor posture, and excess weight contribute to disc degeneration and bulging. Symptoms include localized back pain that may radiate into the hips and legs. MRIs best visualize the protruding disc material compressing nerve roots.

Mild cases without neurological deficits can be managed conservatively with rest, ice, medications, physical therapy, and lifestyle modifications. However, severe bulges causing debilitating leg pain and weakness may require epidural injections or surgical repair. Catching disc bulges early and adhering to treatment helps prevent permanent nerve damage. With a combination of non-surgical treatment and healthy lifestyle changes, most patients achieve relief from the painful symptoms of a L4-L5 disc bulge.