Grade 2 Spondylolisthesis at L4-5 treated by XLIF

Spondylolisthesis occurs when one vertebra slips forward over the one beneath it, most commonly in the lower back. At the L4–L5 level, this slippage can cause back pain, leg pain (sciatica), and nerve compression that affects walking and daily activities.

When conservative treatments like medication, therapy, or injections fail to provide relief, spinal fusion surgery is often recommended. Modern minimally invasive procedures—such as Extreme Lateral Interbody Fusion (XLIF)—allow surgeons to stabilize the spine through smaller incisions, less muscle disruption, and quicker recovery times.

How Common It Is and Who Gets It? (Epidemiology)

Degenerative spondylolisthesis is most common in adults over 50 years old, particularly in women. It often results from age-related wear and tear, arthritis, and spinal instability. The L4–L5 segment is the most frequently affected area due to its high mobility and weight-bearing function.

Why It Happens – Causes (Etiology and Pathophysiology)

Spondylolisthesis develops when the joints and discs that stabilize the spine weaken, allowing one vertebra to slip forward.
Common contributing factors include:

• Disc degeneration: The intervertebral disc loses height and elasticity.

• Facet joint arthritis: The small joints in the back of the spine wear down.

• Ligament weakening: Supporting ligaments lose strength over time.

• Micro-instability: Repeated strain causes gradual forward slippage.

At the L4–L5 level, these changes can compress the spinal canal and nerves, causing symptoms such as back pain, leg numbness, and difficulty standing or walking.

How the Body Part Normally Works? (Relevant Anatomy)

The lumbar spine consists of five vertebrae (L1–L5), separated by intervertebral discs that act as cushions and allow flexibility. The facet joints stabilize the spine while permitting motion. In spondylolisthesis, the balance between these stabilizing structures is disrupted, resulting in vertebral misalignment and nerve irritation.

What You Might Feel – Symptoms (Clinical Presentation)

Typical symptoms of spondylolisthesis include:

• Chronic lower back pain

• Pain radiating into one or both legs (sciatica)

• Numbness or tingling in the legs or feet

• Weakness or fatigue while walking

• Difficulty standing upright

• Pain relief when sitting or bending forward
  In severe cases, nerve compression may cause loss of bladder or bowel control (cauda equina syndrome), which requires immediate medical attention.

How Doctors Find the Problem? (Diagnosis and Imaging)

Diagnosis begins with a detailed clinical examination followed by imaging studies:

• X-rays: Identify vertebral slippage and help classify the degree of movement.

• MRI: Evaluates soft tissues and nerve compression.

• CT scans: Provide detailed bone images, especially useful for surgical planning.

• Flexion-extension X-rays: Assess spinal instability.

The degree of slippage is measured using the Meyerding classification, ranging from Grade I (mild) to Grade IV (severe).

Classification

Spondylolisthesis is categorized by cause and severity:

• Degenerative: Age-related wear and tear.

• Isthmic: Due to a small fracture (spondylolysis) in the bone connecting the joints.

• Congenital: Present at birth from spinal malformation.

• Traumatic or pathological: Due to injury, tumor, or bone disease.
  By grade:

• Grade I: <25% slip

• Grade II: 25–50% slip

• Grade III: 50–75% slip

• Grade IV: >75% slip

Other Problems That Can Feel Similar (Differential Diagnosis)

Conditions with similar symptoms include:

• Lumbar disc herniation

• Spinal stenosis

• Degenerative disc disease

• Facet joint arthritis

• Piriformis syndrome

Treatment Options

Non-Surgical Care

Mild cases are initially managed conservatively:

• Medications: NSAIDs, pain relievers, or muscle relaxants.

• Physical therapy: Core-strengthening and posture training.

• Epidural steroid injections: Reduce inflammation and nerve irritation.

• Bracing: May help in younger or athletic patients.

If symptoms persist or progress, surgical intervention may be required.

Surgical Care – Extreme Lateral Interbody Fusion (XLIF)

XLIF is a minimally invasive fusion technique performed through the patient’s side rather than the back or abdomen.
Steps of the procedure include:

1. Making a small incision on the side of the abdomen.

2. Using a tubular retractor to access the spine through the psoas muscle.

3. Removing the damaged disc and placing a spacer filled with bone graft between the vertebrae.

4. Inserting screws and rods for stabilization.

Benefits of XLIF:

• Smaller incisions and less blood loss.

• Shorter hospital stay (typically 1–2 days).

• Faster recovery and less postoperative pain.

• Lower infection risk compared to open fusion.

Recovery and What to Expect After Treatment

• Immediate postoperative period: Most patients walk within 24 hours.

• Hospital stay: Usually 1–2 days.

• Return to activity: Light activity within weeks; full recovery in 3–6 months.

• Physical therapy: Begins early to improve strength and flexibility.

Most patients report significant pain relief and improved stability within weeks.

Possible Risks or Side Effects (Complications)

Potential risks include:

• Thigh numbness or hip flexor weakness: Usually temporary from psoas muscle retraction.

• Nerve irritation: Rare with real-time monitoring.

• Infection or bleeding: Very uncommon with minimally invasive techniques.

• Non-union (failed fusion): Occurs rarely if bone healing is incomplete.

Long-Term Outlook (Prognosis)

Studies show excellent outcomes for patients undergoing XLIF for L4–L5 spondylolisthesis.

• Over 90% of patients experience lasting pain relief.

• Radiographic imaging after one year typically shows solid fusion with restored alignment.

• Age, BMI, or previous surgeries do not significantly affect success rates.

Out-of-Pocket Cost

Medicare

CPT Code 22558 – Extreme Lateral Interbody Fusion (XLIF): $368.50

Under Medicare, 80% of the approved cost for this spinal fusion procedure is covered once the annual deductible has been met. The remaining 20% is typically the patient’s responsibility. Supplemental insurance plans—such as Medigap, AARP, or Blue Cross Blue Shield—generally cover this 20%, leaving most patients with little or no out-of-pocket expenses for Medicare-approved spinal surgeries. These supplemental policies work directly with Medicare to provide comprehensive coverage for advanced fusion techniques such as XLIF.

If you have secondary insurance—such as Employer-Based Plans, TRICARE, or Veterans Health Administration (VHA)—it serves as a secondary payer once Medicare has processed your claim. After your deductible is satisfied, these plans often cover remaining coinsurance or balance due. Secondary plans typically have a modest deductible, usually between $100 and $300, depending on your policy and provider network.

Workers’ Compensation
If your spinal condition requiring XLIF surgery resulted from a workplace injury or repetitive stress, Workers’ Compensation will cover the entire cost of the procedure, including hospital care, instrumentation, and rehabilitation. You will not have any out-of-pocket expenses under an approved Workers’ Compensation claim.

No-Fault Insurance
If your spinal condition was caused or worsened by a motor vehicle accident, No-Fault Insurance will pay all medical and surgical costs associated with your XLIF procedure. The only potential patient cost may be a small deductible depending on your policy’s terms.

Example
Andrea, a 66-year-old patient with degenerative disc disease and spinal instability, underwent an extreme lateral interbody fusion (CPT 22558) to restore spinal alignment and relieve nerve compression. Her estimated Medicare out-of-pocket cost was $368.50. Because she had supplemental insurance through Medigap, the remaining 20% that Medicare did not cover was fully paid, leaving her with no out-of-pocket expense for the surgery.

Frequently Asked Questions (FAQ)

Q. What is XLIF surgery?
A. XLIF (Extreme Lateral Interbody Fusion) is a minimally invasive spinal fusion performed through the patient’s side rather than the back, minimizing muscle damage and speeding recovery.

Q. Why is XLIF preferred for L4–L5 spondylolisthesis?
A. XLIF allows excellent access to the disc space while avoiding major back muscles. It provides strong stabilization with less postoperative pain and shorter hospital stays.

Q. How long is recovery after XLIF?
A. Most patients return to light activity within 4–6 weeks and resume normal routines within 3–6 months.

Q. Is XLIF safe?
A. Yes. With careful technique and real-time nerve monitoring, XLIF is a safe and effective procedure for grades I–II spondylolisthesis, especially at the L4–L5 level.

Summary and Takeaway

Spondylolisthesis at L4–L5 is a common cause of lower back and leg pain due to vertebral slippage. When conservative care fails, Extreme Lateral Interbody Fusion (XLIF) provides a minimally invasive, safe, and effective solution. It offers excellent pain relief, restores spinal alignment, and helps patients return quickly to active lifestyles with fewer complications and shorter hospital stays than traditional open surgery.

Clinical Insight & Recent Findings

Recent studies confirm that XLIF for grade II L4–L5 spondylolisthesis achieves high fusion rates and patient satisfaction. With the use of real-time neuromonitoring, the risk of nerve injury is extremely low, and outcomes are equivalent or superior to traditional open fusion.

Who Performs This Treatment? (Specialists and Team Involved)

Treatment is provided by orthopedic spine surgeons or neurosurgeons experienced in minimally invasive fusion techniques, supported by anesthesiologists, neuromonitoring technicians, and rehabilitation specialists.

When to See a Specialist?

You should see a spine specialist if you experience:

• Persistent low back or leg pain despite therapy or medication.

• Numbness, tingling, or weakness in your legs.

• Difficulty walking or standing upright.

• Worsening spinal instability seen on imaging.

When to Go to the Emergency Room?

Seek immediate medical attention if you develop:

• Sudden loss of bladder or bowel control.

• Severe or worsening leg weakness.

• Numbness in the groin or saddle area (possible cauda equina syndrome).

What Recovery Really Looks Like?

After XLIF, patients typically walk the same day or next. Initial soreness resolves within days, and significant improvement in back and leg pain is common by the first follow-up visit. Physical therapy supports posture correction and long-term spinal health.

What Happens If You Ignore It?

Untreated spondylolisthesis can lead to chronic pain, progressive slippage, or permanent nerve damage. Early evaluation and treatment prevent long-term disability and improve quality of life.

How to Prevent It?

• Strengthen core and back muscles regularly.

• Maintain proper posture and lifting technique.

• Avoid repetitive spinal strain or high-impact activities.

• Address back pain early to prevent worsening instability.

Nutrition and Bone or Joint Health

A diet rich in calcium, vitamin D, and protein promotes bone fusion and healing after surgery. Avoid smoking, as it slows bone growth and impairs recovery.

Activity and Lifestyle Modifications

After recovery, engage in low-impact exercises like walking, swimming, or yoga to maintain flexibility. Use ergonomic seating and avoid prolonged sitting or heavy lifting.

Do you have more questions?